Stalling and high idle issues

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Muncie
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cars: Vy commodore, ecotec v6

Stalling and high idle issues

Post by Muncie »

Hi All

Currently got 2 issues that are driving me crazy, First is the high idle, starts fine idles at 900rpm then gradually creeps up to 1400 and stays there when in park have gone through everything looking for manifold leaks which i did find a few there fixed now appears the IAC is allowing this air past.

STalling, Car starts ok can be a bit cranky when warm (working on this) goes in to drive fine sits idles as soon as you touch the throttle it falls flat on its face and stalls. if you stab the gas it will pass through it not smoothest way to drive.

Ideas?

Car is a VY turbo Ecotec, Flash ECU Stock Maf IAT in Inlet pipe 850cc Injectors. Pulsar GTX3584RS 60mm Gate
Last edited by Muncie on Sun Jun 30, 2024 7:52 pm, edited 1 time in total.
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vlad01
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Re: Stalling and high idle issues

Post by vlad01 »

Does the TPS have the plastic adapter cap on the end of the throttle shaft? I know for sure the older ECUs raise the idle to something like that after they detect the dead zone of the TPS that occurs when that cap is lost or broken during TPS replacement, also a bad TPS can do the same safe mode type behaviour.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
Muncie
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Re: Stalling and high idle issues

Post by Muncie »

vlad01 wrote: Sun Jun 30, 2024 1:00 pm Does the TPS have the plastic adapter cap on the end of the throttle shaft? I know for sure the older ECUs raise the idle to something like that after they detect the dead zone of the TPS that occurs when that cap is lost or broken during TPS replacement, also a bad TPS can do the same safe mode type behaviour.
That's 100% the first thing I'm going check
Muncie
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Re: Stalling and high idle issues

Post by Muncie »

Alright discovered TPS at rest was reading 14%, everything inside was fine the little adapter was as new after a bit of dicking around i got it to sit at zero at rest and read accurately up to 100%. not sure if thats how you are supposed to set it up but it maid no difference.....

Car still falls flat on its face if you dont stab the gas and keep it alight by riding brakes. discovered at around 2000rpm its pulling as much as 50% fuel through short term fuel trim once its on boost at 2500rpm fuel trim gas back to 0 occasionally adding a little while under load 2-3% max. not sure if this is what i should be focussing on next pull fuel from the 1000-2250rpm range. once it warms up is alot better but still a bit cranky. I'm very green to this stuff i've done a few Hpacademy tuning courses so once the troubleshooting is done i should be good from there.
brindo
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Re: Stalling and high idle issues

Post by brindo »

Can you see what the IAC is doing? How many steps at idle?
Is it opening up on the closed throttle when you have the stalling issue?
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vlad01
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Re: Stalling and high idle issues

Post by vlad01 »

TPS is def stuffed, it should be 0% closed and 100% at WOT, and it should register movement above 0% with the smallest touch of the pedal.

The ECU is running a safe mode for the idle/TPS as a result. The stalling is prob that fact MAF is slow to respond where in the same fault on MAP, you don't get stalling but you get the high idle which is there to prevent the stalling, but the MAP is really good as telling when you are accelerating at light loads where MAF is is pretty slow to respond at light loads and needs the TPS for the throttle transitions.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
Muncie
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Re: Stalling and high idle issues

Post by Muncie »

vlad01 wrote: Wed Jul 03, 2024 11:30 pm TPS is def stuffed, it should be 0% closed and 100% at WOT, and it should register movement above 0% with the smallest touch of the pedal.

The ECU is running a safe mode for the idle/TPS as a result. The stalling is prob that fact MAF is slow to respond where in the same fault on MAP, you don't get stalling but you get the high idle which is there to prevent the stalling, but the MAP is really good as telling when you are accelerating at light loads where MAF is is pretty slow to respond at light loads and needs the TPS for the throttle transitions.
Any idea what might of killed it? I haven't had it apart before i don't want to stick a new one on and kill that too, they aren't cheap at moment and I've learnt my lesson with Chinese parts so it'll be genuine replacement.
Muncie
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Re: Stalling and high idle issues

Post by Muncie »

brindo wrote: Wed Jul 03, 2024 6:30 pm Can you see what the IAC is doing? How many steps at idle?
Is it opening up on the closed throttle when you have the stalling issue?
Idle slowly ramps up iac to 0 steps.
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Re: Stalling and high idle issues

Post by vlad01 »

They just die, wear and heat I guess. My brother's 5L has gone through 4 TPSs at least, I personally never had one fault, but I have lost the adapter cap once which gives the same error code and symptom most often.
I'm the director of VSH (Vlad's Spec Holden), because HSV were doing it ass about.
VTXU8
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Re: Stalling and high idle issues

Post by VTXU8 »

Just throwing this out there as a possible cause for Flat Spot/Stalling issue if new TPS doesn't fix this. I had similar issue with my 5L coming off idle or short stabs of the throttle. I read Holden202t's Basic Guide To Tuning Delcos, on the tuning of spark tables(idle and main spark). Saying to have the idle spark table areas the same as the main spark table or vice versa. Mine were way different to each other so I made the idle table the same as the main spark and it immediately fixed that issue. The spark adv difference going from idle spark to main spark and back was too great of a gap causing it to fall over. Maybe that's something you have overlooked?
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