VT GEN 3 High idle form start

[albion1100]

Hi guys,
Any suggestions would be helpful as this is an on going problem.
When l cold start engine starts easily and revs straight to 1700 rpm.
Starts to slowly drop to normal idle apeed after about 30 - 40 seconds.
When l put it in drive, reverse it engages and the idle apeed increases to 1100 rpm.
Any input greatly appreciated.
Thanks

 

[Tonner Matt]

Those are the symptoms of needing to do an Idle Relearn Procedure

Idle Relearn Procedure for 5.7 Litre V8 with Automatic Transmission
1. Disconnect the battery for 10 minutes
2. Reconnect the battery
3. Turn the Aircon off
4. Put the handbrake on and chock the back wheels
5. Start the engine
6. Put the transmission into Drive
7. Let the engine idle for 10 minutes while in drive
8. Turn the Aircon on
9. Let the engine idle for 10 minutes
10. Put the transmission into Park
11. Let the engine idle for 10 minutes
12. Turn the Aircon off
13. Let the engine idle for 10 minutes.
14. Turn the engine off for at least 30 seconds before restarting

Following this procedure will reset the IAC valve's pintle to it's correct position and return the idle to normal
Whilst not absolutely necessary, it's a good idea to give the Throttle Body, MAF Sensor and IAC valve a clean before doing the relearn procedure......Especially if they haven't been cleaned in a while

 

[albion1100]

Thanks mate for the response.
My AirCon has a leak so isnt working.
Do l still need to include those steps.
Thanks mate

 

[Tonner Matt]

Basically the car is relearning it's idle in drive with the aircon both on and off, and in park with the aircon both on and off.
So yes, you would want the aircon on and working to do the procedure as listed above
I would get the a/c leak fixed and the system regassed before doing the complete above procedure

Alternatively you could try and do it using only the following steps:
1. Disconnect the battery for 10 minutes
2. Reconnect the battery
3. Put the handbrake on and chock the back wheels
4. Start the engine
5. Put the transmission into Drive
6. Let the engine idle for 10 minutes while in drive
7. Put the transmission into Park
8. Let the engine idle for 10 minutes
9. Turn the engine off for at least 30 seconds before restarting

I have never done it this way so cannot confirm if it will or won't work
All you can do is give it a shot and see what happens

 

[albion1100]

Thanks for the response mate. Will try it and see.
Air Con will cost over $1000 to fixso wont be doing that yet.
Thanks again

 

[vr304]

What if you put a new iac valve in? They aren’t that expensive and give the throttle body a good clean while your at it

 

[accentstencil]

What if you put a new iac valve in? They aren’t that expensive and give the throttle body a good clean while your at it

He would still need to do the idle learn procedure, according to the manual anyway.

 

[Nut Kracker]

If you do end up replacing or removing the IAC.
Here's the how to.....
Follow this and then perform the Idle Relearn Procedure posted above.

 

[DLFHUB666]

PCV Line split.