NEED HELP !!! Idling problem driving me crazy!!

Ryan Moilanen · Oct 19, 2017

hello everyone.. I have a 1998 Chevy Silverado k1500 with a 5.7... I am experiencing problems when ever my truck is warmed up it will idle weird when I start it back up again it will go to 800 rpm down to 300 rpm back and forth until I drop it into drive or reverse... also I can feel it stutter when ever I floor it sometimes.. I have no CEL or anything any suggestions? I've cleaned MAF,IAC,throttle body I was thinking an o2 sensor but it would of came up on my code reader if something was off. I've also done a full tune up a few months ago, new fuel filter, upgraded fuel injectors, new fuel pump 2 yrs ago. Any help would be appreciated thanks for reading !

Chewy1576 · Oct 19, 2017

Sounds like an ICM going out. On the TBI trucks, the run more and more rough as the engine gets hotter until it gets so bad the engine quits.

DerekTheGreat · Oct 19, 2017

Chewy1576 said:
Sounds like an ICM going out. On the TBI trucks, the run more and more rough as the engine gets hotter until it gets so bad the engine quits.

That's how my '89 did it. Well, I changed the wires, cap & rotor and then it wouldn't idle. Would start up fine but as soon as it went to lower the idle, dead. Unplugged that brown/tan wire and it was fine though. New dizzy fixed that.

Ryan Moilanen · Oct 19, 2017

Ok guys thankyou for responding Im going to change it out and see if it works I'll keep u updated thanks a lot!!

Ryan Moilanen · Oct 23, 2017

Hello again, so I order a new coil and icm and it still isn't running right. , it's about the same still idle high then low.. my k and n air filter fell out of the snorkel hose and when I was driving I felt so much more power but I'm guessing it was just getting a lot more air? Should I just try and get a new mass air flow sensor? I already cleaned the one I have now.. anything will help! Thanks everyone

DerekTheGreat · Oct 23, 2017

Intake gasket leaking? I'm not really sure, I have no actual experience with Vortec trucks. Primitive, four-eyed TBI lover here.

Ryan Moilanen · Oct 24, 2017

I've sprayed carb cleaner all around hoses and I take gasket and didn't notice anything... I'll try and do a smoke test and see, thanks I appreciate it!

RedLeader289 · Oct 24, 2017

Have you tested the pickup coil? It just sounds like an ignition issue, and since you've replaced the coil and ICM that leaves the pickup coil. . .

Ryan Moilanen · Oct 24, 2017

Ok thanks I will look up how to do that thanks again! I will update as soon as I do

RedLeader289 · Oct 25, 2017

No problem, hope you figure it out. You should be able to bench test it with a multimeter

NEED HELP !!! Idling problem driving me crazy!!

Ryan Moilanen

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Chewy1576

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DerekTheGreat

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Ryan Moilanen

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Ryan Moilanen

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DerekTheGreat

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Ryan Moilanen

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RedLeader289

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Ryan Moilanen

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RedLeader289

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