[ChrisTransAm78]

I know this aint a pontiac issue but I would be much obliged if someone could tell me what's up.

The car runs fine otherwise however when I start it up and let it idle it shows about 3-500. When you put it in gear it dies sometimes. No codes are being thrown. It just idles very low and seems to be getting lower and lower by the days. Anyone ever see this?

Thanks,
Chris

[onetru462]

Check fuel pressure and volume (correct spelling??). Terrible reliability issues with these pumps,and this is just one of the many problems we have seen it cause. Also won't throw codes when this happens.

[george kujanski]

I've got an '01 Yukon but no problem (yet). You are scareing me, tho.

The computer should be keeping idle speed constant once it goes into closed loop. Either it is trying to but the idle air bypass motor is not responding (I would think that would set a code) or it thinks it's ok, meaning it's not reading the engine speed correctly.

Does it run ok off idle?

Vacuum leak of some kind?

George

[ChrisTransAm78]

Yeah it runs fine if you get it to go...it kind of stumbles and then goes. Once going goes smooth. Not sure about a vacuum link since but I have not been in there doing anything. It idles so low that the AC starts going warm. If you sit and manually idle it up the AC works fine. Guess its idling so low that the AC is out of its operating range.

So Andy you've see it actually cause this type of issue?

[JSchmitz]

I had an idle problem with my '00 Silverado. It has a 6.0. It would idle rough and not want to restart after shutting down for short epriods. It was a bad fuel regulator. It's on the driver's side fuel rail. Pull the vacuum line off. If fuel runs out, it's bad.

[onetru462]

Sorry for late response. Yes have corrected this issue due to this before, but as w/ any fuel injected problem, can't say it isn't the regulator or not (Easy enogh to know after checking pressure and volume). I have also seen the pressure look fine, but the volume way off.What is it J Hand says..."7 psi of nothing is..well...7 psi of nothing!!" (Yes I know we are talking about allot more than 7psi)

[ChrisTransAm78]

So I assume I would need a guage to check pressure and volume ? Is there a wiz bang one I can get somewhere on the cheap ?

Thanks,
Chris

[LouisianaGuy]

you can get a pressure guage from Autozone I think for a few bucks to check pressure, and the volume deal ...well I dont know if their guage has a release valve on the side to check for volume...we had a cool one at the shop that you could floqw fuel out off from a lil valve on it and catch iot in a jug and measure it.
May wana claen the IAC motor for good measure.
This can cause low idle problems as well if its sticking.
Mike
Mike

[cioccoj]

I will assume that it has a 5.7 in it. Weve had a few of those in our shop that ended up being a bad intake gasket. Spray all around the intake and see if anything changes.

[buwalda]

I have had two fuel injected Mitsubishis that have had the same slow, rolling idle, cutting out some times. They were company cars, so I didn't do the work on them. But in both cases, it was an idle solenoid or motor [ not sure which ], that operated at idle & provided bypass air. What happened was the small air opening carboned up, reduced air intake & slowed the idle. Remedy was to clean it out.

["Guy]

Hey Chris, Try the coolant sensor.... To test it just unplug it, if it still running the same she shot or the ohm test...If it's loading up at idle the coolant sensor is in the cold mode during hot running. Sometimes the coolant sensor will not show up because it's still working just not the way it should be...