The car will crank and run for a few minutes at idle then just cut off. Have to wait a little while for it to start again. While idling it will bog down when you try to accelerate the idle. it is a tune port engine. The car has 40,000 miles on it. Have replaced plugs wires and diet. cap to rule that out. Im pretty sure its either fuel or vacuum.
If you have good spark at the plugs then it is vacuum or fuel.
1 vac listen for hiss in the few min it runs
check lines for damage, splits, unhooked etc. don't forget under car and dash
2 check fuel pressure, check for fuel delivery to the cyl. remove spark plug crank and check small look for fuel. remove coil wire so it won't start on you.
MIKe
SOURCE: 95 GMC Jimmy 4.3l W vin rough idle
My problem was solved when I repaired my 4 wd activation dash switch. The switch was contacting on 2WD & 4HI at the same time. The front differential activation is vacuum activated possibly creating a tug of war that didn't actually engage it but drained off vacuum from the engine? A theory at best but stumbbled across it because I knew the switch wasn't working properly I repaired it and low and behold rough idle disappeared and all is good for 3 weeks running.
SOURCE: 1996 Chevy Express 1500 w/5.0 bogging only when warm.
The cylinder 7 misfire is likely a symptom of the problem, not the problem itself.
Typically, the catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream 02 sensor reading should be fairly steady. Typically the P0420 code triggers the check engine light if the readings of the two sensors are similar. This is indicative of (among other things - such as faulty sensors in the "emissions loop") a converter that is not working as efficiently as it should be.
I do not believe that it is a problem with a valve/head gasket or cam.
SOURCE: hesitates on acceleration
Does the car always hesitate during acceleration? If it ALWAYS struggles when it starts or ALWAYS hesitates on acceleration then I would say the issue is fuel delivery. If the problems are more intermittent and come-and-go then it could be an electrical issue.
I would start by changing the fuel filter. Changing plugs, wires, cap, and rotor are all good things to do as your budget will allow. I doubt you will have to change your injectors.
If you end up replacing any rubber fuel line, be sure to use the high-pressure stuff made for use on fuel injected cars.
I hope this helps! -Nick
SOURCE: Rough idle and acceleration on 1998 Chevrolet Silverado 5.0
Bad EGR valve comes to mind here. Assuming the plugs are good, the EGR valve woiuld be what I'd look at.
SOURCE: 87 chevy 350 fuel injected pickup wont run smoothly
sounds like your egr valve is gummed up or bad. this is located behind the throttle body and has a single vaccum tube connected to it. if the diafram is still good you can remove it and clean it with WD 40 until the plunger works smooth
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