'90 G20 5.7L Running Bad

Kingcool · 01-31-2008, 07:45 AM

I have a '90 chevy G20 5.7 TBI. Hard starting, stalls couple of times. When finally moving runs pretty good. When it gets halfway warm bogs big time, you can push down on gas pedal 2 inches w/no response. Only way to get acceleration is to put it on the floor, but it still bogs. When it is fully warm runs pretty good for the most part. If you stop the engine for 15mins then restart, engine runs really bad, shakes sputters won't accelerate. If you let it run that way for 5min it clears up and runs pretty good. I have changed fuel filter, air filter, cap, rotor, plugs, wires, had injectors cleaned, timing set, checked for vaccum leaks. Computer puts out no codes. Any HELP would be appreciated. THANKS...

jimbo543 · 01-31-2008, 10:29 AM

i'm wondering if your minimum air rate is too low

you'll have to knock out the idle screw plug and turn in 1/4 turn, not too much and recheck linkages, best to do with a scanner when warm, check iac counts you want 10-20, would also check iac pintle for dirt

replace egr valve, spring in valve gets weak causing stumble/lag

strokin350 · 01-31-2008, 03:15 PM

i had a simalar problem on my 92 gmc and it turned out to be the coolant temp sensor.

01-31-2008, 07:45 AM	#1
Kingcool Junior Member Join Date: Jan 2008 Posts: 1	'90 G20 5.7L Running Bad I have a '90 chevy G20 5.7 TBI. Hard starting, stalls couple of times. When finally moving runs pretty good. When it gets halfway warm bogs big time, you can push down on gas pedal 2 inches w/no response. Only way to get acceleration is to put it on the floor, but it still bogs. When it is fully warm runs pretty good for the most part. If you stop the engine for 15mins then restart, engine runs really bad, shakes sputters won't accelerate. If you let it run that way for 5min it clears up and runs pretty good. I have changed fuel filter, air filter, cap, rotor, plugs, wires, had injectors cleaned, timing set, checked for vaccum leaks. Computer puts out no codes. Any HELP would be appreciated. THANKS...

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01-31-2008, 10:29 AM	#2
jimbo543 Senior Member Join Date: Sep 2007 Location: MN Posts: 205	i'm wondering if your minimum air rate is too low you'll have to knock out the idle screw plug and turn in 1/4 turn, not too much and recheck linkages, best to do with a scanner when warm, check iac counts you want 10-20, would also check iac pintle for dirt replace egr valve, spring in valve gets weak causing stumble/lag

01-31-2008, 03:15 PM	#3
strokin350 Senior Member Join Date: Sep 2007 Posts: 72	i had a simalar problem on my 92 gmc and it turned out to be the coolant temp sensor.