WH Statesman 3.8Ltr 6 cyl with a Dangerous issue

[Immortality]

Said egr not the problem, I think lout might be onto something with the temperature sender.

Not likely as no-where in the idle speed table is it requested to idle that high regardless of temperature.

My understanding is that the IAC stepper motor resets itself at every start, so when you turn they key to on it bottoms itself out and then opens itself to the required number of steps dependant on ECT (there is a specific table for this). Once the car starts the IAC then works off a target idle speed also dependant of ECT. High idle for the coldest of temps is about 1000rpm IIRC.

This is the idle tables for a L67 but it's very similar to the ecotec.

 

[Immortality]

These are some of the IAC settings. The stepper motor has a range of 0 to 255 steps. 170 steps on a cold start will see you get about 1500-1600rpm on a cold start momentarily. Fairly much no-where in the tune is it ever commanded to go all the way to 255 steps which is what would be required to 2500rpm idle.

A dodgy TPS will keep the engine out of idle of it's not reading the throttle is closed and will hold the IAC open but again nothing is commanded over 170 steps so does not explain the 2000 rpm + idle.

 

[VFSV6FORME]

Was it doing it before you changed the LIM gasket?

Well today I will try to find from the 3 parts outlets, autobahn,supercheap and repco the MID section of the LIM gaskets as the MID gasket in the new kit was the the O ring type and the car needs the paper/steel gaskets.
I hope this fixes the issue otherwise I'm stump.
Anyhow If I get the parts today I might have wait to next Monday because its BATHURST weekend and my eyes will be glued to the TV.

 

[VFSV6FORME]

These are some of the IAC settings. The stepper motor has a range of 0 to 255 steps. 170 steps on a cold start will see you get about 1500-1600rpm on a cold start momentarily. Fairly much no-where in the tune is it ever commanded to go all the way to 255 steps which is what would be required to 2500rpm idle.

A dodgy TPS will keep the engine out of idle of it's not reading the throttle is closed and will hold the IAC open but again nothing is commanded over 170 steps so does not explain the 2000 rpm + idle.
View attachment 207241

Yes this car is a CROCK. The TPS has been replaced, I checked it with the Multi Meter using a needle and the ignition on with the multi meter and at idle (throttle fully shut) and I found 0.50 Volts and after this i gave 10% more throttle and the Volts went up to around 0.90 and at half throttle it was around 2.4 Volts and as FULL throttle it was 4.6 Volts. Now after this I went up and down to see if I have any flat spots which was none. It ramped up and down correctly

 

[Immortality]

If yours has the steel type gasket just reuse it with a very thin smear of sealant on it. I've done it for years with a MACE spacer and it works fine. Just make sure the surfaces are clean of oil from the PCV passage before re-sealing.

edit: I wonder if it might be a wiring issue? If the PCM is loosing signal/count it will keep trying to add more steps. No way to tell unless you log the car though.

 

[Trevor loves holden.]

Just wondering have you tried a reset on your ECU.

 

[VFSV6FORME]

Just wondering have you tried a reset on your ECU.

No. how do you do this

 

[VFSV6FORME]

I will be back on this NEXT MONDAY as Its BATHURST 1000 time. I need a rest with this car
Back on Monday after I replace the Mid Gasket as I got a complete LIM Gasket kit with two different types of that Gasket (NOT the O-ring one)

 

[greenacc]

No. how do you do this

I believe all you need to do is disconnect the battery for a while. If you are not in a hurry leave it off for an hour so the system will reset

 

[Trevor loves holden.]

Remove PCM/BCM fuse and allow the capacitors to drain for a bit, or like was said remove the negative battery terminal well since your doing the gasket you should remove it anyway.