My winter transportation is an 88
Chevy 1500 pickup 5.7 TBI.
Runs fine until it warms up.
Idles iraticaly and stalls at lights.
No check engine codes. Changed O2 sensor.
Know two others with the same problem.
Dealeships and shops cant seem to fix
can someone out there help me?

 

May be a vacuum leak, but it has something to do with the iac as that is what controls idle. Could also be a bad map sensor. I'm sure others will offer more ideas soon as well.

Steve

 

Yeah I'd check IAC and MAP first, as Steve said. Maybe even the CTS if those aren't the problem. Goodluck

 

yea for sure check your iac, couldnt it also be the tps?

 

Don't overlook a sticky or leaking EGR valve, or an EGR solenoid that is leaking through. A little EGR gas goes a long way toward killing an idling engine, especially when hot and in closed loop, when the fuel is trimmed pretty tightly.

Just another possibility.

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Later,
Vader
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"Fear is how I fall, Confusing what is real..."
Adobe Acrobat Reader

 

When I had a similar problem with mine, it was the fuel pump, could check into your pressure, but I'd check the above mentioned items first... easier and more probable.

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~Luke a.k.a. pianiy = drunk (in Ukrainian)
'91 Firebird :: 305/TBI(L03)/700R4/T-tops ::
Mods: Catco high flow cat - B&M Shift kit - TA tail light conversion - K&N - MacEwen white faced guages
Stereo: Pioneer DEH-P8200R - Pioneer 6x9's - Kenwood 8" Tube
'87 Firebird :: LB8/700R4/220K :: R.I.P. ::
Firebird parts - Got an '80 Firebird for sale too
Moderator of tranny board over at TransAmGTA.com

 

Wow, I'm having the EXACT problems as you. I'll bet money it isn't your IAC since you said it idles erratically. I don't think EGR is the problem either. A Vac leak or the MAP sensor is the only thing I can think of. TPS sensor is also a good thing to have checked but I'm sure if you took it to a mechanic they would have looked at that, if not, don't go back to them. Fuel pressure shouldn't be a problem since it is running but stalls at when load is placed on the engine.
RGS1260: Does it stumble when you try to accelorate hard? Any backfire? Does it mis bad and then die? How is the voltage? Because my volts go low under 900rpm and I think it's because my alternator is going bad.

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, Jon (350 TBI!)
91 Red My website