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How is VY2 V6 Idle Contolled / Set pse?

vk4akp

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Hi, One of my 2004 VY2 V6 Wagons has had a rough idle right from when I bought it. (I'm 3rd owner).

History of the car is it is an Ex Gov Police Spec vehicle. (Ex QAS rural fast response vehicle)
2nd owner had 3 different LPG conversions done to it in his time as owner and was never happy. Sold the car to me with the LPG removed. I note one of the conversion types involved drilling into the inlet manifold to add additional LPG injection points. These holes have been plugged with bolts. I have sprayed them with CRC to look for vacuum leaks but all looks good.

However I believe it was never setup correctly again for petrol.
It had LPG plugs still fitted for starters. Once replaced with the correct NKG Iridiums the fuel economy and idle improved dramatically.

However it still idles rough and as specially when turning the wheel to park or reverse it tends to stumble and recover often causing the car to lurch a bit which is not safe really when trying to park. The power steering drag tends to make it worse.

The idle seems to be set for 650 RPM.

I have adjusted the butterfly by one additional half turn in (opened further) which helped a lot. I know we are not supposed to touch this setting but the red cap was gone and there was white thread lock on the adjustment screw. So I have assumed that they had played with this setting for LPG use.

I have an ALDL interface and TunerPro. It says target idle in the ECU is set to 650 RPM.

Now my questions for the Guru's.

- What is the correct idle setting for this car?
- How is the idle set?
- Is there anything in the ECU (computer) flash that can be set or changed for the idle setting?
- I did wonder if the sticker on top of the radiator contained any useful information? It has fallen off of both of my VY2 Wagons unfortunately. (Anyone got a photo of one?)

Any help appreciated.
.-.-.
 

immortality

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Idle is set in the tune and controlled by the PCM.

You can set the butterfly correctly using tunerpro, run the engine up to temp, make sure all the accessories are off and then adjust the butterfly until the IAC stepper motor is showing between 20-30 steps.
 

vk4akp

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Hi, Thanks. Where in the tune is the Idle set? I'll have a look to see if it's been changed from factory due to the LPG.
Also what is stock idle RPM for the VY2 V6 L36 Ecotec (Auto / 4L60E)?
I'll check the IAC steps when I have the other info so I can do it all together.
BTW. I should mention I have replaced the IAC & TPS on this car with good quality new units from Repco.
Thanks again for your help :)
.-.-.
 

vk4akp

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OK. I've just found I have a log file from the last time I had a play with the butterfly adjust screw.
I didn't do too bad with my guessing. But something is still wrong I think due to the rough idle.
Back then I had
IAC Step - 31-32 Fluctuating at idle. So I was close just by guessing what felt / sounded right.
Idle 720-740 RPM (Fluctuating wildly). Fluctuation value 1-4.
Target Idle seems to be set to - 737 RPM in the ECU.
I'll include the Log file here if you feel like a look at it. :)
.-.-.
 

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immortality

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Ahh, not sure. If you have tunerpro find a copy of the stock tune and check what it says.

Fluctuating idle can be a stepper motor problem, clean the TB or a vacuum leak, check for leaks.
 
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