# 97 chevy 2500 funky idle



## mean green 24 (Oct 13, 2010)

Hey guys I have 97 silverado with a vortec 454 it seems to idle funny at times,meaning it will idle really low or rpms will be low while plowing motor can even shake at times and then all of a sudden take off and run like a champ. Its a real pta when your plowing. I thought it might have been idle air control or water in the gas but its not. Any ideas? Its not throwing any codes.


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## b&b landscapes (Nov 7, 2010)

sounds like tune up time, almost like a wire is arcing at times..... most of the time a on and off miss is a habit of bad wires/cap


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## MickiRig1 (Dec 5, 2003)

When it's acting up check your fuel pressure. Make sure the fuel pressure regulator is working.Take the vacuum line off while running, it should increase idle speed. If it don't it may be getting tired. Change the fuel filter lately?


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## mean green 24 (Oct 13, 2010)

MickiRig1;1201602 said:


> When it's acting up check your fuel pressure. Make sure the fuel pressure regulator is working.Take the vacuum line off while running, it should increase idle speed. If it don't it may be getting tired. Change the fuel filter lately?


I have not changed the filter,just got the truck in november. That's easy enough I will try that but what do you mean getting tired?which vacuum line do I pull off?


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## mean green 24 (Oct 13, 2010)

b&b landscapes;1201584 said:


> sounds like tune up time, almost like a wire is arcing at times..... most of the time a on and off miss is a habit of bad wires/cap


I bought the truck in november and I went by the guys word that it was all done. Didn't have any problems when I got it but tune ups are fairly cheap I will give it one. Thanks.


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## mean green 24 (Oct 13, 2010)

mean green 24;1202951 said:


> I have not changed the filter,just got the truck in november. That's easy enough I will try that but what do you mean getting tired?which vacuum line do I pull off?


Also truck only has 86k on it I know that it doesn't mean crap but its clean.


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## Rc2505 (Feb 5, 2007)

Never trust a seller. They are going to tell you waht you want to hear. The day after I get a used truck, I always change the oil, all filters, plugs, wires, cap, service the tranny, and both axles. Just to be safe.


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## nick.saporito (Jan 19, 2011)

hey, new to the site, I just bought an older fisher 7'6" speedcast for my 97 chevy 1500. the type thats all hydrolic and mounts under the hood. is there some kind of bracket i have to make or can I buy it. also what am I suposed to do about adding a pulley to drive the belt. i have a 5.7. also would it be a total wast of time to change it over to an electric pump if I can do it cheaply? thanks hope my questions arent too stupid


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## mean green 24 (Oct 13, 2010)

Don't quote me but on mine there is a seperate bracket for the pump and the belt is its own belt mine spins the closest 3 or 4 lines to the radiator. You could check the fisher plow section good luck.


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## THEGOLDPRO (Jun 18, 2006)

my 97 454 chevy does the same exact thing. idles rough but clears up when driving and runs mint.


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## 70monte (Feb 5, 2008)

My 98 K3500 with the 454 also idles rough but runs fine at speeds higher than idle. Mine has been fully tuned up with new plugs, wires, distributor, cap, rotor, coil, fuel filter, and air filter. I bought it with 94,000 miles on it and it currently has 103,000 miles on it. Mine never idles low though so I don't know what that might be.

THEGOLDPRO, your truck looks pretty much like mine. Here is mine.


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## THEGOLDPRO (Jun 18, 2006)

they are almost exact twins


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## MickiRig1 (Dec 5, 2003)

There should be some sensors that may effect the control of the idle. Such as the Throttle Position Sensor,MAP sensor and Temp sensor.The emissions section in repair manuals have check procedures for the sensors. Might think about changing out the oxygen sensor. It may be giving funky signals to the computer. But, not funky enough to trigger the check engine light.


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## 70monte (Feb 5, 2008)

That is a nice truck THEGOLDPRO. How many miles on it? I forgot to mention that I also replaced the two precat O2 sensors with two new AC-Delco ones on mine. My gas mileage did go up slightly but the idle roughness was the same. I also cleaned the MAF sensor. I've read that the 454 is not known for idling very smooth but who knows if that is true. I do know on another website I go to some of those guys with this engine also complain of the idle quality. Good luck and let us know what you figure out.

Wayne


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## mass1589 (Jan 24, 2011)

anyone ever update this with a fix???

im having the same exact issue with my idle!!!!


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## THEGOLDPRO (Jun 18, 2006)

I replaced the plugs&wires and my idle cleared right up.


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## Banksy (Aug 31, 2005)

THEGOLDPRO;1611098 said:


> I replaced the plugs&wires and my idle cleared right up.


Somebody zip tied the plug wires together in my 90 2500 in an attempt to secure them. I have a feeling that the slight bump at idle could be them arcing together. A full tune up is on the list.


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## mass1589 (Jan 24, 2011)

Soo far ive done plugs wires fuel filter oil change cleaned throttlebody. Still when truck warms up as soon as it goes from park or nuetral to drive or reverse, wen the brake is
Pressed and the truck is in idle the rpms drop to 400 and surge back up to 1100 all on their own. Its almost a perfectly timed cycle too. 

No codes, motor dips soo low it almost stalls out 
Sucks to plow like this i cant figure out what would cause this after ive replaced everything.


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## MickiRig1 (Dec 5, 2003)

Does it have fuel injection? Could be Idle Air Control. Check fuel presssure, Take vacuum line off pressure regulator when it's at idle,RPM should go up.


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## matts27 (Dec 21, 2007)

mass1589;1611150 said:


> Soo far ive done plugs wires fuel filter oil change cleaned throttlebody. Still when truck warms up as soon as it goes from park or nuetral to drive or reverse, wen the brake is
> Pressed and the truck is in idle the rpms drop to 400 and surge back up to 1100 all on their own. Its almost a perfectly timed cycle too.
> 
> No codes, motor dips soo low it almost stalls out
> Sucks to plow like this i cant figure out what would cause this after ive replaced everything.


If its a throttle body, check for vacuum leaks around the base of the throttle body and the intake manifold. If idle speed advances you've got a leak, just a thought...

Matt


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## mass1589 (Jan 24, 2011)

Its a 5.7l fuel injected


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## chevboy167 (Dec 7, 2011)

Possible intake gaskets leaking, broken or frayed vacum lines/hoses, fuel injection spyder assembly fault/broken line. Have a shop with a smoke machine hook up to your EVAP system service port, inject the smoke into the intake system and look for leaks around intake gaskets, vaccum hoses, vapor canister and lines that run under the truck if there are any.


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## mass1589 (Jan 24, 2011)

Wow thanks alot!! Im gonna run it by my local shop this week!! 
Any idea why it would only leak during drive or reverse?? The engine intake manifold wouldnt change any way from different gears??


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## chevboy167 (Dec 7, 2011)

Any updates/fixes on your problem???


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