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On a 2005 Chevrolet Astro Van(AWD, 4.3L V6 with about 33-34k miles), it has a no start condition but I also found out it stalls once I let go of the gas pedal, prior to jump starting.
Here are a few things I noticed while verifying the problem:
-The engine will not start even with a jumper pack.
-It only starts(with jumper pack) when my foot is on the gas pedal.
-As stated in topic title, it stalls once I release the gas pedal.
-Only once, it did not stall when at idle.Side note: The van in question hardly gets driven compared to the Truck/Sedan but still gets once a week check and up to operating temperature. Until recently, it doesn’t seem to even crank normally like all the other times.
I’m believing it might be the IAC valve(or related) but I still need to look further more under the hood. Since last time, I didn’t spend much time when I was helping with Thanksgiving preparation.
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If you have any check engine lights start there. With a crank no start condition you need to look at what’s missing, spark, fuel, or a mechanical issue. You may be onto something with the IAC, if it’s not working correctly then it can upset the mixture when you try and start the engine. You might try tapping on it with the butt of a screwdriver to see if it frees up and starts working. FYI I don’t have a lot of success with ‘cleaning’ an IAC, I think it’s much better to replace them.
I know, with a no start condition, air, fuel and spark are needed to fully crank an engine over. Or in some occasions, it’s more mechanically, but I was able to crank it over(with foot on gas pedal, just not without).
No check engine light though, but the IAC was fairly clean/in good condition when I shown it to a couple ase master techs I know of(note I’m more entry level tech). It doesn’t stall anymore and there were no damaged or corroded wires either. I also do not need to apply throttle just to turn it over anymore. I got it verified(the next day) if the same people(the ase master techs) were able to figure out if something doesn’t sound right with the engine in idle and applying throttle but each of the three said no(with a visual inspection as well).
Once the idle stall disappeared, I tried a few times to see if I was able to get it to stall again after applying a bit of throttle and releasing but it does not want to anymore.
With that said, I’ll just have to keep an eye on it from time to time.
Thanks for the reply also.you mentioned the battery being dead and needing a jump pack. The ECM has an idle learn strategy that gets erased when the ECM loses power. This is an adaptive strategy, meaning the computer will learn to adjust the IAC position based on deposits that build up on the throttle body. This is what I believe your issue was. A loss of memory and a dirty throttle body. After fixing your battery issue and driving it the ECM relearned proper IAC position again. Clean your throttle body if this issue presents itself again
[quote=”ScannerDanner” post=40306]you mentioned the battery being dead and needing a jump pack. The ECM has an idle learn strategy that gets erased when the ECM loses power. This is an adaptive strategy, meaning the computer will learn to adjust the IAC position based on deposits that build up on the throttle body. This is what I believe your issue was. A loss of memory and a dirty throttle body. After fixing your battery issue and driving it the ECM relearned proper IAC position again. Clean your throttle body if this issue presents itself again[/quote]
A very reasonable explanation. Thanks ScannerDanner. It’s an honor to have you hear helping out.
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