# big engine problem, need help



## elite1msmith (Sep 10, 2007)

big engine problem

2001 dodge ram 2500 4x4 5.9 gas with about 100 k on it

after the motor is run about 20 mins, it starts to stall and die at idle,...progressively getting worst , until the entire motor is bogged down and the Rpm will not go over 2000 under load...if you put it in neutral and can manage to get it over 3000, the problem instantly stops and the motor runs smooth

the only code that came up was for a bad CMP (cam sensor) or timing chain

I replaced the CMP , with no luck

if you let the motor cool off, then it starts up again no problem, at least for 10 more mins

thanks guys ,


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## Midwest BuildIt Inc (Nov 14, 2004)

does it seem like its running out of fuel? I had a problem like that once and if i put more fuel in the truck it would be fine again. turned out to be the adjustable depth fuel pump screws came loose and it would float on top of the fuel in the tank.. It was totally random when it happen and drove me nuts till i figured it out....had to drive around with a fuel pressure gauge duck taped to the window for a month. lol .


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## weeman97 (Dec 4, 2005)

kind of sounds like when me cat. took a poop on me(wow sound re word that but o well)


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## elite1msmith (Sep 10, 2007)

its not fuel pressure i dont think because it runs fine for 20 mins, and even if it acts up and i put it in park/neutral , the rpm will rev up

I thought maybe the Cat, its getting that time, maybe it takes about 20 mins for the back pressure to build up, enough to start messen with the engine, Is there a check for this? or should i just disconnect the exhaust and take it for a drive?


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## scottL (Dec 7, 2002)

are you stating the time as 20 minutes or do you mean to say that when the engine temp comes to operating temperature? Most emissions kick in when fully warmed up. Maybe a component there.


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## elite1msmith (Sep 10, 2007)

yes, i do mean while its cold, it seems ok, when it warms up is when it starts to bog out

yeah the o2 senors kick in when they hit 600 degrees as the book says, but iv never heard of an o2 sensor , going bad, and bogging out the engine......normally they just go bad, and the computer just goes back to defaul mode, and then gives you a check engine light


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## ServiceOnSite (Nov 23, 2006)

try the coolant temp sensor. when its warm it could still be dumping fule like it does when its cold to warm up. i had a 1500 do this to me before. as soon as it warmed up it would barely run. just a shot the part is only like 10-20 bucks


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## elite1msmith (Sep 10, 2007)

ill have to check that one out, it might be the case....come to think of it, that would explain y if you get the rpm above 3000 it runs better, il give it a shot and let u know


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## AHammen (Dec 28, 2007)

Don't throw out the possibility of a bad O2 sensor. I had one go out on a Dodge truck before and it caused the truck to sputter and die, I had to put the truck in neutral and keep the rpm's up for it to stay running.


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## elite1msmith (Sep 10, 2007)

well heres what i have figured out to this point....the Cam shaft sensor has been replaced and im still getting the same code

i got the truck to "act up" and i cooled down the coilk, thinking it was over heating....still no good

drilled a small hole in the exhaust to check back pressure....the cat checks ok,...at least we think so

tommarow im gonna try the crank postion sensor, also I believe it happens when the PCM goes into closed loop mode after the engine is at operating temps.....at that point the PCM starts reading some of the senors ...like the O2, 

Also we measured the "slope or back lash" between the crank shaft and distributor rotor......it was estimated to be about 10 degrees and the book, said if thats the case, then remove timing chain cover and do closer inspection of the chain....stretched out?

we did this test 4 times, coming up with 10 degrees each time

This would cause the Cam Senor to be behind, and cause the injectors to fire late...something to think about


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## 2003ctd (Sep 4, 2007)

Sounds like your timing is off, a plugged up cat wouldn't cause it to die, you just would not have any power.. You would have noticed a cat getting worse and worse, it would not have just started acting up... Your distributor may be bad, or the timing chain may be stretched... Those 5.9's run for ever have never heard of one throwing a chain at 100k but anything is possible!


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## elite1msmith (Sep 10, 2007)

ignition timing is controlled by the crankshaft senor......while the distributor does dirrect the spark....the coil only fires when the PCM tells it to...based on the crankshaft sensor

the CAM senor (located in the distributer) does the timing for the fuel injection....... 

it is critical that the CAM pulse, be prior to the Crank pulse ..or else the whole PCM will not function correctly

f the distributor is off,....the Cam Pulse will be behind ...and may not be apperaing prior to the crank pulse...but i would need a scope to look into if thats the case

but backlash/ or slop in the chain would cause the distributor to be behind....


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## elite1msmith (Sep 10, 2007)

well i pulled the cover....

1/2 inch of play side to side ??


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## elite1msmith (Sep 10, 2007)

i ordered the chain? i dunno


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## Crash935 (Sep 3, 2003)

Sounds like a stuck EGR valve.


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## elite1msmith (Sep 10, 2007)

i will put the egr on the next list of things to check...that could be, the exhaust on this truck for some reaseon looks very rusty


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## elite1msmith (Sep 10, 2007)

welll its not the chain, I dont think its the coolant sensor, as i tried playing with it....


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## krazeehorse (Jul 3, 2008)

You ever put a set of plug wires on it?


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## elite1msmith (Sep 10, 2007)

yes like 3 times...new cap , wires..i thought that too, but this is def. a computer/sensor problem.....

the problem is figuring out which sensor, or if its the computer


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## elite1msmith (Sep 10, 2007)

well i thought id bump my own post still have the problem, havent looked at the truck in a month

what i beleive is happening , is when the computer kicks into closed loop mode it starts backfireing , and will barly do 20 mph... sounds like the timing is way off, not even close 

i have changed the CAM sensor, and the timing chain, - tips i got from other ppl

im still kinda looking for help, currently the throttle is sticking, not due to the cable, maybe the sensor , from siting still all summer


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## gskara (Sep 3, 2008)

nothing here tells me that you have put a fuel press gauge on it. many of times I have had filters nearly clogged that fuel gets delivered fine untill the overworked fuel pump (from the clogged filter) overheats and stops working. have seen a time delay of a few minutes to a half hour before acting up.


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## elite1msmith (Sep 10, 2007)

i dont believe it has a filter

and heres why its not a fuel pressure issue. if i put the truck in park,, once the problem has started,

put your foot slowly to the floor it will chug, and backfire, the RPM will very slowly rise ove r a 30 second period.. the moment the RPM hits 3000 , inteastly the problem is fixed,, and the enige will near red line till you take your foot off the gas, once the RPM drops, you have the same problem

if it were fuel pressure, i wouldnt be able to get the RPM up in th efirst place, also once the problem begins to start i could shut the truck off... restart it 15 mins later... and its even worst, and the truck sat and cooled off for 15 mins... which makes me think it has to do with the closed loop mode, it takes alot for the O2 sensors to cool back down


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## terrapro (Oct 21, 2006)

hmmm there was a way to keep it from going into closed loop mode that could atleast help determine one thing for you. if i could only remember how to do that?

ill try to get back to you on that one.
------------------------------------------------------------------------

you could take your thermostat out completely. unless its really hot out you shouldnt go into closed loop mode.


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## elite1msmith (Sep 10, 2007)

B&B you got anything on this one?


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## JD Dave (Mar 20, 2007)

elite1msmith;578584 said:


> i dont believe it has a filter
> 
> and heres why its not a fuel pressure issue. if i put the truck in park,, once the problem has started,
> 
> ...


I don't beleive that's the problem but yes it has a filter.


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## cretebaby (Aug 23, 2008)

does it have a oil pan lol


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## cretebaby (Aug 23, 2008)

or is it a 2 stroke LOL


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## elite1msmith (Sep 10, 2007)

well posibly a filter in the tank , but none in line


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## Moonlighter (Mar 31, 2008)

5.9L dodges have a fuel filter and a fuel regulator attached to the fuel pump unit inside the tank. Could it be a poor gas problem, I had that happen with mine, I used fuel system cleaner in two tank fulls and mine cleared out. Have you checked the injectors with a stethescope, crisp crack means good, squashy crack means not good, It is a multi-point fuel injected right. Each cylinder gets its own injector, then you could rule out injectors. Timing chain shouldn't move a 1/2 in either way, you may have the problem licked. Hope this helps.
Checked my book, is there any poor condition vacuum lines, also says to check the bolts connecting to intake. A light soapy water mix sprayed on will bubble up if any leaks are present. Other than that book leads to low compression, bad plugs or wires but you said you have changed those regularly. Is coil output what it should be?
________________________________
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"We play in the snow while you sleep!"


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## elite1msmith (Sep 10, 2007)

like i said, truck runs perfect till it gets warm, then it goes to ****... let it cool , and its all good for anouther 10 - 20 mins,, i hight dont think its fuel related,

but i did do new gas, and fuel system cleaner


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## Moonlighter (Mar 31, 2008)

Sorry I didn't read carefully enough, sounds like your coil is taking a s**t when it heats up.


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## gskara (Sep 3, 2008)

eliminate all possibilities. quit spectulating. check fuel pressure w/ gauge. all filters clog inline or tank. also pressure regulators stick.


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## elite1msmith (Sep 10, 2007)

Moonlighter;578808 said:


> Sorry I didn't read carefully enough, sounds like your coil is taking a s**t when it heats up.


see that was up there on the guessing list, so i had a friend stand therte with an aire hose, and a spray bottel to keep it cool, ... no difference,

it belive it has to do with the timing or the pulse of the injectors


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## elite1msmith (Sep 10, 2007)

b&b? anything?


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## B&B (Nov 4, 2006)

If your shotguns empty it's time get it on a scanner and check the MAP and TPS data readings, need to check it both cold AND hot... Think your gonna find one or the other is dropping out from the engine heat. And neither will normally set a code. The 5.2 and 5.9's eat TPS sensors.

Make sure you go over the engine to battery, engine to frame, and engine to body grounds as well as they will cause all sorts of strange drivability issues that will seem heat related...and actually are.


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## elite1msmith (Sep 10, 2007)

see thats funny you say that , my throttle is sticking, and i think its because of the TPS, holding it up , hopefully this will be the isue

the code from the scan came back as 1391. which is the code for a cam sensor/ or crank sensor....

we did the cam sensor, i guess im going to try the crank, after fixing the TPS? i have talked to other dodge mechanics and they seem sure its not the crank sensor because it always restarts

cam does fuel timing, crank does spark timing


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## elite1msmith (Sep 10, 2007)

F**** Emmisions , and computers, that all im saying ,

now i cantt even get it to start


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## SnoFarmer (Oct 15, 2004)

I have had numerous TPS fail and I never got one of them to throw a code.
I even had a 5star tech(HAHAHAHA) ride with me with his fancy scan tools.
The results were the same as I got with my cheep one "No codes returned"

I put a new one in and problem. solved

Get a MOPAR tps as the aftermarket ones last half as long.

Try a tps then go to the crank sensor. The Map rarely go bad on these.


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## elite1msmith (Sep 10, 2007)

well it was startin g, now i cant even get spark, 

im so fustrated with this D--- truck , 

It was"my personal" - towing , was minimized, never beat it hard...

has seen 7000 miles in the last year, in that 7000 , i have put a tew tierod end, entire rear axle, rebuilt the trans,new t stat, new rad. and a full tune up, and now this engine problem, it changes its symptoms so much that its hard to trouble shoot, now i cant even get the truck to start at all.

Im seriuosly thinking about parting the thing out , and buying another cummis, ... this gasser is crap- and its the only one in the fleet


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## accentlawn (Nov 17, 2007)

if you want to take it out of closed loop disconnect an o2 sensor.


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## elite1msmith (Sep 10, 2007)

see funny thing was, i started it this morning.... it ran for about 2 mins fine, then started to get rough... i gave it gas to keep it running , finnally it died

let it sit about 1 hr.... i was doing some reading , and figured that out.... so i did disconnect the o2 sensor, and now it will not start... i reconnected it, same thing , no start


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## elite1msmith (Sep 10, 2007)

well got it to start again? how i dont know

running rough, im going to stick with my orginal plan and drain all the fuel out, and put new in, clean the plugs , go from there


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## red07gsxr (Dec 22, 2007)

its not going to be a fuel issue. i think your wasting your time with that whole issue. disconnecting the o2 sensor is not going to start or cause your truck not to start. you could have a sensor that is failing for your computer in the truck could be your issue. the computer could be dropping the signal to the sensor which is causing your issues. i would stop putting money and time into parts. either borrow or find a scanner that reads and shows values and get the specs on what your truck should be at. once started and your reading values, record and see what sensor drops. i would start there. a spark plug is going to work or not. not come on or off. start with finding values of your sensors and going from there. remember the computer could be your main problem. just my 2 cents.


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## elite1msmith (Sep 10, 2007)

we have run a scanner a few times , with different codes coming up, the fuel has been in there since may, and for what ever reason this truck ssems to burn threw a set of plugs every year or too ill tell you the first to go cly 7, it burns ver little to no oil either

before i start messing around, and checking values for each sensor, im goona make sure i have the basics first

yes the engine would not give me a spark today , this motor over heated a while back , and did the same thing, no spark till it completely cooled, i think that was the ASD relay doing it

but basicly thats the next step, thing is... i reasurced this problem with alot of ppl saying they never found an anwaser.... took it to a dealer , put a PCM in it ...runs for 2 weeks , then same problem, i had heard of a few ppl just giving up and parting out the truck, one guy is a member on this site -

also the point of disconnecting the o2 sensors was too keep in the computer in open loop mode just to see what it would do...... 

i will be using a multi meter and checking the voltage drops at all the sensors this week, i was told a big thing to watch for on a scope, was the cam sesor must pulse before the crank ....


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## B&B (Nov 4, 2006)

elite1msmith;592156 said:


> we have run a scanner a few times , with different codes coming up,
> 
> i will be using a multi meter and checking the voltage drops at all the sensors this week


 If your not checking the various sensor feedback WITH THE SCANNER then your not using it to its full potential. You can check virtually every sensors feedback to the ECM with the scanner _in real time_...including the cam/crank pulse during a no start condition.

If you can't, then you don't have a scanner..you have a code reader. Two completely different things.


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## elite1msmith (Sep 10, 2007)

i dont own a scaner, so i have to barrow one from a friend... i do have a scope....


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## red07gsxr (Dec 22, 2007)

you could have a bad crank sensor or your timing chain could be streched. i have seen it happen before on other manufactors but usually a sensor is bad its bad, doesnt come and go.


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## elite1msmith (Sep 10, 2007)

already replaced the timing chain, as i thought that was the problem , it had some slope in it.

iv asked liek 8 mechanic friend of mine to take a quick look , and each one was like ??? i have no clue - 

im told if it was the crank sensor that it wouldnt spark....at all

i was told check the O2 sensors, cooland temp sensor, map, tps, ...so i guess thats my next step. I just want to be sure first that i have good fresh gas in it... it 4 months going on 5 months old ... so just in case, i dont want to over look that. and i guess shoudl be checking the fuel pressure as well

i just dont want it to turn into , a neck,dime thing, with no solution in sight....


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## red07gsxr (Dec 22, 2007)

i understand where you are coming from. i would deff hook up a scanner and get the value and see if any of them drop. i dont think your fuel is bad. i left gas in my plow truck for 8 months and it started and ran perfect with no problems. i suggest you get the spec sheet from a dodge service manual or from the internet.


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## elite1msmith (Sep 10, 2007)

ok, new fuel - just to be safe

fuel pressure tests good

i put a noid , injector light on it, and i was getting no signal from the computer to fire the injectors

measured signal voltage on both the cam and cranck sensor... the cam, gave us a proper reading, but at times was hard to get ( i dont have a scope) ...i couldnt really get much from the crank sensor,...so we tryied to remove it , couldnt get to it....

tryied restarting, and it started up, ran , if you held your foot on the gas.. then after a few attempts it wasnt working again, ...and we had done nothing but crank it over....

It does have spark the entire time, becasue we could run it under a starting fluid stream

just loses its injector pulse


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## red07gsxr (Dec 22, 2007)

the computer is running the injector pulse, you could have a bad ecm/pcm. if the injectors are not firing and you do have fuel pressure then i would have to say the computer is bad. its not uncommon to replace the computer. i would check to wiring from the injector to the computer to make sure you dont have a open in the wire.


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## elite1msmith (Sep 10, 2007)

wiring is good, sometimes it works others not

how much is a new computer?


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## RepoMan207 (Oct 7, 2008)

MASS Air Flow Sensor............... The same exact thing happend to my brothers truck last week. We drove around for hours with his Snap On tool hooked up. We never got the right error code either. When it has a "fit", and you apply the throttle, it bogs down a bit. But in the same hand if you feather the throttle just so, and get it up to a higher RPM it will come out of until the RPM's come back down. We did the "apply brake and accelerator trick" but eventually that didn't even work. Anyway, we changed the MASS sensor and it runs good. He has the the 02 5.9 with 130k. Hope that all it is. Good luck!


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## red07gsxr (Dec 22, 2007)

RepoMan207;610846 said:


> MASS Air Flow Sensor............... The same exact thing happend to my brothers truck last week. We drove around for hours with his Snap On tool hooked up. We never got the right error code either. When it has a "fit", and you apply the throttle, it bogs down a bit. But in the same hand if you feather the throttle just so, and get it up to a higher RPM it will come out of until the RPM's come back down. We did the "apply brake and accelerator trick" but eventually that didn't even work. Anyway, we changed the MASS sensor and it runs good. He has the the 02 5.9 with 130k. Hope that all it is. Good luck!


the truck will not run, its not getting injector pluse, it will only stay running with a good stream of starter fluid. as far as a computer goes, i would try to find a used one, the truck doesnt have a imoblizer or anything like that. i would try to swap computers with a another truck and see if things change. i wouldnt get a new one unless you know for sure that its the issue. i would go to a local junkyard that sells good quality used parts and see if you can purchase one. used and new computers have a huge price difference. but deff make sure you dont have a open in the wire. thats not very uncommon.


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## festerw (Sep 25, 2003)

RepoMan207;610846 said:


> MASS Air Flow Sensor............... The same exact thing happend to my brothers truck last week. We drove around for hours with his Snap On tool hooked up. We never got the right error code either. When it has a "fit", and you apply the throttle, it bogs down a bit. But in the same hand if you feather the throttle just so, and get it up to a higher RPM it will come out of until the RPM's come back down. We did the "apply brake and accelerator trick" but eventually that didn't even work. Anyway, we changed the MASS sensor and it runs good. He has the the 02 5.9 with 130k. Hope that all it is. Good luck!


I think you might be confused since there isn't a MAF on a Dodge gas 5.9, there is a MAP and IAT sensors though.

Elite, have you had the battery tested? I've had issues on a couple Dodge trucks and some Jeeps with a battery being strong enough to start it but causing other weird issues don't ask me how it makes sense, lol.


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## lake_effect (Feb 5, 2007)

I think you are on the right track with the crank sensor.....I should know, on my fouth one in my '96 Ram.

And yes, they are a royal PITA to get to and change.

My first one was the hardest to diagnose as it was the most intermitten. Out of no where, truck would just die and refuse to start until it cooled off. Then it would start right up and run fine for a day, a week or whatever, and when you least expected....it would do it again. Slowly got worse and worse to where it would want to die as soon as it started to warm up....would idle fine, put it in gear and would sputter, puke and die. Took forever, but finnally found it by wiggling every wire under the hood and found the one which made it die. The original CPS looked like they used a fence strecher to install it, wires were pulled so tight that over time, the wire insulation was pulling out of the sensor, the wires were shorting and one was frayed down to about two strands.

Second one was diagnosed and fixed no problem.

Number three....long story short...was bad right out of the box. Put it in, truck started once ,run like total crap then died and would not restart. Got the same code you're getting so I replaced the cam sensor and distributor. Didn't help so I spent the next two weeks checking EVERY sensor, relay, every inch of wiring, fuel pump / filter. injectors, plugs and on and on and on. Finally, frustrated, I put the old CPS back in and it started right up, ran fine till it warmed up and died. And of course, Advance Auto gave me a hard time about returning it, even though it didn't work from the get go. Got my money back and went to NAPA for number four which has outlasted all previous CPS's.

Sounds like you've checked / replaced just about everything that I went through with my third CPS. And your symtoms are fairly identical. They dont always just completely fail. They seem to degrade and malfunction intermitently. And they don't last forever. You can check to see if the sensor is getting the correct voltage (5v IIRC) and see if the sensor signal is pulsing correctly while cranking.

The CPS isn't that expensive and if I were you, I'd try that before you pull out any more hair....from what I've read, I'd bet the farm on this being your problem.

Good luck, electrical gremlins suck.


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## red07gsxr (Dec 22, 2007)

i thought you replaced the sensor....if not replace wit like we have all said before. use factory parts. i dont like aftermaket unless i am stuck in a corner,


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## brad96z28 (Aug 21, 2005)

For christs sake will someone scope the sensor at the sensor and at the computer to know what u are dealing with . If u dont have one bring it to someone that does. It may have wiring issue to the sensor or from the sensor to the computer U can throw sensors at it all day but if u have a wring problem It is all for nothing.


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## elite1msmith (Sep 10, 2007)

brad96z28;613441 said:


> For christs sake will someone scope the sensor at the sensor and at the computer to know what u are dealing with . If u dont have one bring it to someone that does. It may have wiring issue to the sensor or from the sensor to the computer U can throw sensors at it all day but if u have a wring problem It is all for nothing.


yeha im workign on that , i dont have a scope, but i have a really good volt meter. I could see the pulse output of the cam sensor - no problem

couldnt get one on the crank sensor. i does have power to it .... that i checked, it has ground as well....

so i guess next step is the sensor -

thanks for your your thoughts-


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## brad96z28 (Aug 21, 2005)

elite1msmith;613537 said:


> yeha im workign on that , i dont have a scope, but i have a really good volt meter. I could see the pulse output of the cam sensor - no problem
> 
> couldnt get one on the crank sensor. i does have power to it .... that i checked, it has ground as well....
> 
> ...


Wish U where closer to me, Id help you out. Has the dist ever been out or rotated? If u clear that code does it come rite back?


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## elite1msmith (Sep 10, 2007)

no the dis has not been out, the cap and plugs were done last winter -

i appreate the offer - 

i might just break down and buy one....

but the muti meter i have is really good, especially for 5 volt systems, - liek i said it would easy pick up the cam pulse... i could watch it go up and down , just couldnt get anything on the crank


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## brad96z28 (Aug 21, 2005)

elite1msmith;613547 said:


> no the dis has not been out, the cap and plugs were done last winter -
> 
> i appreate the offer -
> 
> ...


I use a snap on vantage pro. Otc came out with a reasonably priced scope I think Its a solarity. About $1100 comapred to $2500 for the vantage pro. Is that 1391 a hard code? If u clear it does it comes back as soon as u try to start it? Multimeters are not really good for cking most sensors other then ohms or volts. U really need to be able to view waveforms.


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## elite1msmith (Sep 10, 2007)

so we replaced the crank sensor...it came to LIFE...ran great.... for all of a few days, even plowed for 2 storms

then when u left it idle for more than 3 mins, it slowly died... on itself

now , the problem is getting worst and giving me the sam syptoms as before

the motor sputters, backfires a few times, and u can jsutbearly bring the rpm up


but it is still driveable at this point....for now anyway

i really dont know what to do - i might jsut sell the truck


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## earl ohio (Feb 13, 2005)

is the intake gasket leaking? i had similar probs with my 95 5.2 and it was the pick up in mydistributor. i raplaced all kinds of stuff before i tried that. just a thought.


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## Spitz (Feb 28, 2008)

Wow, prime example of throw parts at it and hope. First you say you have a scope, then its a volt meter instead. Im not getting the backyard mechanic thing anymore.. There is too many things to know and its too expensive to guess anymore with parts. The truck will go into closed loop within a matter of under a minute, the newer the vehicle is, the faster its going to happen. You say you've "checked" it all and its "good" but what are your figures?? What kind of backpressure at idle, at 2500rpm? What is fuel pressure, what is fuel pressure when the truck acts up? Does the truck sit outside? Any rodents nests around?


ps- voltmeter is def. no subsititue for a scope, reading a voltage thats changing faster than you see or the meter to even change.. A scope gives you a waveform. I would be doing a voltage sweep on the TPS , usually the middle wire in the three wire connector to see if its dropping out at all.


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## elite1msmith (Sep 10, 2007)

umm we didnt throw too many parts at , simply replaced what the "code said to"


no we didntscope it , i guess we need to ,... but the thingis ,... afterwe installed this sensor, it ran good for almost a week , no problem ... and prior to it , i couldnt even start the truck up

now all of a sudden the syptoms are slowly comign back

i have had 4 different profesional mechianics check it out .... yes the fuel pressure test good... by the book , it tests good

when it acts up the injectors dont fire, becasue the computer shuts down , due to alack of signal from the crank sensor..... so wereplaced it , problem fixed for 1 week - now what?


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## BigLou80 (Feb 25, 2008)

elite1msmith;693632 said:


> i have had 4 different profesional mechianics check it out .... yes the fuel pressure test good... by the book , it tests good
> 
> when it acts up the injectors dont fire, becasue the computer shuts down , due to alack of signal from the crank sensor..... so wereplaced it , problem fixed for 1 week - now what?


One of those professional mechanics should have a scope !


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## Crisch (Dec 11, 2008)

You said you checked fuel pressure, but did you actually check to see if you have enough fuel volume? A fuel pump after it gets hot can produce the same symptoms you are describing. A lean condition will cause an engine to backfire. Did you look to see what the oxygen sensors are doing after it goes in to closed loop? These trucks are famous for having bad fuel pumps. I have personally replaced tons of them at my shop.


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## elite1msmith (Sep 10, 2007)

Crisch;693731 said:


> You said you checked fuel pressure, but did you actually check to see if you have enough fuel volume? A fuel pump after it gets hot can produce the same symptoms you are describing. A lean condition will cause an engine to backfire. Did you look to see what the oxygen sensors are doing after it goes in to closed loop? These trucks are famous for having bad fuel pumps. I have personally replaced tons of them at my shop.


i guess no , we did not check the fuel volume... to tell u the truth i was concered about the volume. i had disconnected the fuel line at the rail , to run the tank dry, in an effort to put fresh fuel in it.... and it seemed to come out with just a trickle after bypassign the fuel relay. but the thing that the mechanic told me was.... if u check the pressure with the motor running, and it holds the correct pressure, then the pump must be good, becasue its keeping up with the demand of the truck

plain and simple we put a noid light on the injectors and u ca n see when it acts up , the injectors STOP firing.....


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## elite1msmith (Sep 10, 2007)

BigLou80;693725 said:


> One of those professional mechanics should have a scope !


u you would think. these guys are mechanics , but work in smaller shopps, so the "scope" belonged to the shop.... and i couldnt get my hands on it


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## BigLou80 (Feb 25, 2008)

elite1msmith;693810 said:


> u you would think. these guys are mechanics , but work in smaller shopps, so the "scope" belonged to the shop.... and i couldnt get my hands on it


I think at this point its safe to say that money spent on paying the shop to use thier scope is money well spent. Think of all the money you could have been making instead of taking all this time to not fix your truck


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## elite1msmith (Sep 10, 2007)

BigLou80;694030 said:


> I think at this point its safe to say that money spent on paying the shop to use thier scope is money well spent. Think of all the money you could have been making instead of taking all this time to not fix your truck


you would think that, except I have been askign around about this... i have talked , or emailed about 6 different ppl , that have this SAME EXACT problem ... they took it to the dealer, or different shops... a few tried the computer, a few put a new sensor like i did

all 6 of these ran fine for 2 weeks after what ever repair ... and then the problem came back, one guy is sellign the truck , another is parting it out.

I have no problem paying some money, but if they tell me its a computer, and then 2 weeks later the problem is back ...i just wasted alot of money. We tested the sensor as bad, theerror code in the computer came back bad sensor , so it was safe to assume that was the problem....any dealer would have done the same thing, and after reinstalling it, send me on my way -


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## snow plowman (Feb 27, 2008)

un plug the bank 1 senser 1 o2 senser and try that my truck did the same thing and i unplug the o2 senser bank 1 sensor 1 the plug is on top of the trans un plug it and try that if fix my prob and all i had to do is put a nw one in no more probs


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## elite1msmith (Sep 10, 2007)

ill check it out- thanks for the tip, but i thi nk i tried that already...but its worth another shot


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## Green Grass (Dec 5, 2006)

If you replace the crank sensor again does the problem go away again? Where did you get the crank sensor? Is your intake leaking when it gets warm?


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## Green Grass (Dec 5, 2006)

SUBJECT: Engine Cranks But Does Not Start Or Starts And Stalls
DATE: Sept. 8, 2000
NOTE: THIS BULLETIN APPLIES TO VEHICLES EQUIPPED WITH A VEHICLE THEFT ALARM (VTA) SYSTEM (SALES CODE LSA).

DISCUSSION:
Part of "No Start" diagnosis on vehicles equipped with VTSS should include a verification check of the power supply to the Central Timer Module (CTM). The CTM provides the Powertrain Control Module (PCM) with an "OK To Start" message via the CCD bus. If the message is not received by the PCM, the PCM will not allow the engine to start. Initially, the engine may start and stall but will eventually not start at all. Most CTMs are supplied battery voltage through the power door lock fuse. An inspection of the fuse should be one of the initial diagnostic checks performed. If the fuse is operational, a verification check of the communication system from the CTM can be performed using the DRBIII®. Attempt to communicate to the CTM. If the CTM does not respond to the DRBIII®, the DRBIII® will identify a "No Response From Central Timer Module" message. A "No Response From Central Timer Module" message may indicate that the CTM is not powered up. Please refer to the "Communication" section of the appropriate Body Diagnostic Procedures Manual to assist in "No Start" diagnosis due to communication problems from the CTM. In addition, the "Vehicle Theft/Security" section will aid in the diagnosis of "No Start" issues involving the VTSS system.


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## eds1200 (Dec 26, 2008)

change the crank sensor.


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## elite1msmith (Sep 10, 2007)

Green Grass;694491 said:


> If you replace the crank sensor again does the problem go away again? Where did you get the crank sensor? Is your intake leaking when it gets warm?


i dont know if the intake is leaking , were is a good place to check? i heard th eback of the motor

i only replaced it one time , so fare... and with a OEM - mopar


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## elite1msmith (Sep 10, 2007)

eds1200;694508 said:


> change the crank sensor.


as stated it was chaged once already, ran fine for 2 weeks or so , n ow the problem is slowly coming back


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## Green Grass (Dec 5, 2006)

check the intake by spraying carb clean around the intake with the vehicle running and see if the RPMS change Mopar parts have a 12 month or 12,000 mile warranty bring it back and get a different sensor and try it if you are still getting the code that is what normally causes the code is a crank sensor. Also check the crank sensor wiring to ensure that it is not rubbing and grounding out. Was the code for voltage high or low? or for signal circuit?


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## elite1msmith (Sep 10, 2007)

code was 1391 i think.... its been awhile


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## Green Grass (Dec 5, 2006)

Symptom:
P1391-INTERMITTENT LOSS OF CMP OR CKP

When Monitored and Set Condition:
P1391-INTERMITTENT LOSS OF CMP OR CKP

When Monitored: Engine running or cranking.

Set Condition: When the failure counter reaches 20 for 2 consecutive trips.

POSSIBLE CAUSES:

CMP SENSOR OUT OF SYNC
DAMAGED TONE WHEEL/FLEX PLATE (CRANKSHAFT)
DAMAGED TONE WHEEL/PULSE RING (CAMSHAFT)
IRREGULAR LAB SCOPE PATTERN OF CMP SIGNAL
INTERMITTENT CKP SIGNAL LOSS WHEN WIRING IS WIGGLED
IRREGULAR LAB SCOPE PATTERN OF CKP SIGNAL
WIRING HARNESS INTERMITTENT
INTERMITTENT CMP SIGNAL LOSS WHEN WIRING IS WIGGLED
SENSOR CONNECTOR/WIRING
SENSOR CONNECTOR/WIRING
CAMSHAFT POSITION SENSOR
CKP SENSOR CONNECTOR/WIRING
CRANKSHAFT POSITION SENSOR

TEST ACTION APPLICABILITY

Start the engine and run until operating temp is reached. (Closed Loop)
With the DRBIIIt under the Misc. menu, choose the Set Sync Signal function and
observe the Actual Sync Setting.
Does the Actual Sync Setting read In Range?

Yes ® Go To 3
No ® Loosen the CMP sensor base hold down bolt and turn the base
until the sync is RANGE on the DRBIIIt.

3. Turn ignition off.
With the DRBIIIt lab scope, back probe the CMP signal circuit at the CMP sensor
harness connector using Miller special tool #6801.
Warning: Keep clear of the engine’s moving parts.
Start the engine.
Observe the CMP sensor voltage pattern on the lab scope screen.
Are there any signals missing?

Yes ® Go To 4
No ® Go To 7

4 Turn the ignition off.
Visually inspect the related wire harness connectors. Look for broken, bent,
pushed out, or corroded terminals.
Visually inspect the related wiring harness. Look for any chafed, pierced,
pinched, or partially broken wires.
Note: Make sure the Camshaft Position Sensor and/or the Crankshaft
Position Sensor is tight.

Yes ® Repair as necessary.
No ® Go To 5

5 Turn the ignition off.
Disconnect and remove the camshaft position sensor.
Inspect the tone wheel/pulse ring for looseness and/or physical damage.
Is the tone wheel/pulse ring free from defects?

Yes ® Go To 6
No ® Repair/replace tone wheel/pulse ring as necessary.

6 If there are no possible causes remaining,
Replace the Camshaft Position Sensor.
.

7 Turn the ignition off.
With the DRBIIIt lab scope, back probe the CKP signal circuit at the CKP sensor
harness connector using Miller special tool #6801.
Warning: Keep clear of the engine’s moving parts.
Start the engine.
Observe the CKP sensor voltage pattern on the lab scope screen.
Are there any signals missing?

Yes ® Go To 8
No ® Go To 11

8 Turn the ignition off.
Note: Visually inspect the Crankshaft Position Sensor and related wire
harness connectors. Look for broken, bent, pushed out, or corroded terminals.
Note: Visually inspect the related wiring harness. Look for any chafed,
pierced, pinched, or partially broken wires.
Note: Make sure the sensor mounting bolt(s) are tight.
Were any problems found?

Yes ® Repair as necessary.
No ® Go To 9

9 Turn the ignition off.
Disconnect and remove the crankshaft position sensor.
Inspect the tone wheel/flexplate slots for damage, foreign material, or excessive
movement.
Is the tone wheel/flexplate free from defects?

Yes ® Go To 10
No ® Repair/replace tone wheel/flex plate as necessary.

10 If there are no possible causes remaining,
Replace the Crankshaft Position Sensor.

11 Turn the ignition off.
Visually inspect the related wire harness connectors. Look for broken, bent,
pushed out, or corroded terminals.
Visually inspect the related wiring harness. Look for any chafed, pierced,
pinched, or partially broken wires.
Note: Make sure the Camshaft Position Sensor and/or the Crankshaft
Position Sensor is tight.
Note: Refer to any technical service bulletins that may apply.
Were any problems found?

Yes ® Repair as necessary.
No ® Go To 12

12 Turn the ignition off.
With the DRBIIIt lab scope, back probe the CKP signal circuit at the PCM harness
connector using Miller special tool #6801.
Warning: Keep clear of the engine’s moving parts.
Start the engine.
Observe the lab scope screen while wiggling the wiring harness and connectors
related to the CKP sensor.
Were there any irregularities in the lab scope pattern when the wiggle test was
conducted?

Yes ® Note where wiggling caused a missing CKP sensor signal. Repair
CKP sensor wiring as necessary.
No ® Go To 13

13 Turn the ignition off.
With the DRBIIIt lab scope, back probe the CMP signal circuit at the PCM harness
connector using Miller special tool #6801.
Warning: Keep clear of the engine’s moving parts.
Start the engine.
Observe the lab scope screen while wiggling the wiring harness and connectors
related to the CMP sensor.
Were there any irregularities in the lab scope pattern when the wiggle test was
conducted?

Yes ® Note where wiggling caused a missing CMP sensor signal. Repair
CMP sensor wiring as necessary.
No ® Test Complete.

14 Turn the ignition off.
Connect the DRBIIIt lab scope to the CMP signal circuit. For best results, back probe
at the PCM harness connector using Miller special tool #6801.
WARNING: Keep clear of the engine’s moving parts.
Start the engine.
Observe the lab scope screen while wiggling the wiring harness and connectors.
Were there any irregularities in the lab scope pattern?

Yes ® Check harness and connectors carefully. If OK, replace the
Camshaft Position Sensor.
No ® Go To 15

15 Turn ignition off.
Visually inspect the related wiring harness. Look for any chafed, pierced,
pinched, or partially broken wires.
Visually inspect the related wire harness connectors. Look for broken, bent,
pushed out, or corroded terminals.
Note: Refer to any technical service bulletins that may apply.
Were any problems found?

Yes ® Repair wiring harness/connectors as necessary.
No ® Go To 16

16 Turn the ignition off.
Connect the DRBIIIt lab scope to the CKP signal circuit. For best results, back probe
at the PCM harness connector using Miller special tool #6801.
Warning: Keep clear of the engine’s moving parts.
Start the engine.
Observe the lab scope screen while wiggling the wiring harness and connectors.
Were there any irregularities in the lab scope pattern?

Yes ® Check harness and connectors carefully. If OK, replace the
Crankshaft Position Sensor.
No ® Test Complete.


Here is the official tests for your code just follow the test procedure and hopefully it will lead you to your issue notice every step is numbered and it will have you jump to different steps depending on the results you find. I hope this helps.


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## elite1msmith (Sep 10, 2007)

if i had a drb


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## Green Grass (Dec 5, 2006)

just need any scan tool that will show you data. must be more then a code reader


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## Lydia Moore (Dec 18, 2008)

If you have the major problem with your engine then the better idea is too sell your truck to the truck buyer..It will give you more.


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## lake_effect (Feb 5, 2007)

*Take it back!!!*



elite1msmith;692740 said:


> so we replaced the crank sensor...it came to LIFE...ran great.... for all of a few days, even plowed for 2 storms
> 
> then when u left it idle for more than 3 mins, it slowly died... on itself
> 
> ...


Like I said 2 months ago.....sounds like the crank sensor. Ran like a new truck when you put it in, didn't it?wesport

Like I also said, I'm on my fourth CPS for my '96. CPS #3 was junk right out of the box, and I know I'm not the only one that has experienced this, or having a newer one fail seemingly premature. I've been through 2 OEM and 2 aftermarket.

When my second OEM CPS started screwing up (less than a year old) I took my truck to the local stealership and asked them to diagnose it for possible CPS or plugged cat. They scoped it and told me the CPS and cat were fine, but handed me a bill for $90.00 and a list (nearly $1500.00 worth if memory serves) of things that they said needed to be fixed. Timing chain, distributor, cam sensor, cap, wires, coolant sensor, TPS, serpentine belt and a few other things I'm probably forgetting.

Talk about throwing parts at a problem......

Anyway, told them no thanks, and was on my way. I replaced that CPS (with the one that was bad right out of the box) and wasted two weeks trying to figure that out. Finally replaced the CPS again and haven't had a lick of trouble since. Bought that one (good) from NAPA, can't remember the manufacturer, but it's held up better than the OEM's.

They can be bad right from the box, or even shortly after being installed. Most of this crap is made in China or Mexico anymore.

If it is OEM and you bought it from a stealership, I would suggest you take your truck over there and ask for a replacement. If nothing else, like they don't believe the new'ish CPS could be bad, tell them to throw your truck on their Star Scan and prove it.

And yeah, I did go back to the stealership and raised hell with the service manager and got my $90.00 back for their inacurate diagnosis. Friggen retards.

It's a tough call, worked for me and did get my money back for the defective part. It can drive you nuts, but sometimes the answers are so simple and we keep overlooking the obvious.

Again.....good luck!


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## N.W.Plow (Nov 8, 2008)

are you still working on that?


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## daninline (Nov 1, 2004)

how long has this truck not been running right this is crazy.
I don't know what to say that hasn't been said a few times now.
I also have seen a battery issue that would make my Jeep with a 5.2 run with out power.

have you tried to unplug the intake air temp senser this will change a lot of setting and if it's reading to hot it will pull timeing out of the motorand change the fuel curve


I have a 1996 Jeep with a 5.2 with about 400,000 miles on it and I've never changed more then the water pump in all that time to the motor. no sensors and only one o2 senser.
I I have a motor waiting for it now just in case 

Good luck


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## elite1msmith (Sep 10, 2007)

lake_effect;696914 said:


> When my second OEM CPS started screwing up (less than a year old) I took my truck to the local stealership and asked them to diagnose it for possible CPS or plugged cat. They scoped it and told me the CPS and cat were fine, but handed me a bill for $90.00 and a list (nearly $1500.00 worth if memory serves) of things that they said needed to be fixed. Timing chain, distributor, cam sensor, cap, wires, coolant sensor, TPS, serpentine belt and a few other things I'm probably forgetting.
> 
> Talk about throwing parts at a problem......
> 
> Again.....good luck!


see thats eaxtly the reason i dont want to take it to a dealership. I did end up replacing the timingchain ( i will say it was running much smoother) but that wasnt the fix

I will check the intake for leaks, and possibly anew sensor again

this is what i noticed this last time .... if yoru driving it , it acts fine... if you leave it idle for more than 3 mins, then it acts up... once it starts acting up ,...the only good way to fix the problem is ..shut the truck off... then restart ...and it seems fine , provided you dont let it idle too long again

or ... you can basicly pump the gas petal for like a min straight while its acting up and running, and at some point the RPM will come up enough , and what ever is boggin down the motor will go away

thanks to everyonestime ant thoughts


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## red07gsxr (Dec 22, 2007)

your just wasting time and money. bring it to someone that knows what there doing.


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## theplowmeister (Nov 14, 2006)

I have not read ALL the posts sounds to me like a sensor, connector or controller is going bad when it heats up. when it runs badly try cooling off each item. Garden hose works.


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