VX, rpm drops and almost stalls when idling.

[dumpedvs]

Hey guys, My vx has had trouble idling when im sitting at traffic lights or just idling for about 30 seconds.
Ive only noticed it after I got the fuel pump/fuel pump wiring loom changed.

If im sitting at traffic lights for a little while it will drop down to about 400-500 rpm like its going to stall, then it will jump back up again.
It only does it when im idling for a longish period of time. Its fine when im driving it tho.

Any solutions?

Cheers, Cal.

 

[Ghost]

It may be a fuel pressure problem or crappy fuel or fuel filter

 

[vx_commodore]

Hey guys, My vx has had trouble idling when im sitting at traffic lights or just idling for about 30 seconds.
Ive only noticed it after I got the fuel pump/fuel pump wiring loom changed.

If im sitting at traffic lights for a little while it will drop down to about 400-500 rpm like its going to stall, then it will jump back up again.
It only does it when im idling for a longish period of time. Its fine when im driving it tho.

Any solutions?

Cheers, Cal.

Check the IAC for proper function.
May just need a clean.
Or MAF, But unlikely, But it's worth a check.

 

[sleepinvt]

find the problem? i started my car today and had the same problem, idling 500rpm, revving fine though

 

[dumpedvs]

Nah have not found the problem yet, going to give the mechanic who fixed my fuel pump and ask him about it,

 

[BlackVXGTS]

You can try the Holden Idle relearn procedure as specified below. However, it seems over the top for me. You could try reducing the idle period to (say) five minutes or just persevere and it should come good after a couple of days of running:

IDLE LEARN PROCEDURE
Whenever the PCM or the battery is disconnected or
the PCM loses power, the PCM’s learned position of
the IAC valve pintle is lost, resulting in an unstable
idle.
Perform the following procedure in order to return
the IAC valve pintle to the correct position:
Automatic Transmission
1. Turn OFF the ignition.
2. Restore the PCM battery feed.
3. Turn OFF the A/C controls.
4. Set the park brake and block the drive wheels.
5. Start the engine.
6. Shift the transmission selector to D (drive).
7. Allow the engine to idle for 10 minutes.
8. Turn ON the A/C controls.
9. Allow the engine to idle for 10 minutes.
10. Shift the transmission selector to P (park).
11. Allow the engine to idle for 10 minutes.
12. Turn OFF the A/C controls.
13. Allow the engine to idle for 10 minutes.
14. Turn OFF the engine for 30 seconds.
Manual Transmission
1. Turn OFF the ignition.
2. Restore the PCM battery feed.
3. Turn OFF the A/C controls.
4. Set the park brake and block the drive wheels.
5. Place the transmission in neutral.
6. Start the engine.
7. Turn ON the A/C controls.
8. Allow the engine to idle for 10 minutes.
9. Turn OFF the A/C controls.
10. Allow the engine to idle for 10 minutes.
11. Turn OFF the engine for 30 seconds.

 

[rpwc]

Hiya - I have a 2005 VZ Calias that has the exact symptoms. Pull up for traffics lights etc for about 30 sec and revs suddenly drop engine rough then recovers. This would sometimes result in the motor stalling when you try to accelerate from the lights and even when going slow for a corner etc. Have had the ECU changed, the crank angle sensor replaced and coils/plugs replaced. (Kia/Heartland services have tried a new throttle body (as idle control value is not separately changeable in VZ) which did not help. They suspected that the new coils that were put on were the cause as they are not genuine GMH and tried some genuine ones and while they said this 'improved' the situation it did not eliminate it. I then asked them to check fuel pressure at idle to see if the fuel pump may be causing this but the test said all OK. The only thing that is not standard on this car is the alternator that I replaced with a GMH genuine 'police car' spec (ie higher output) alternator - I don't think this is the issue. I was thinking the MAF may be contributing but this was tested as OK. I will try the idle learn procedure indicated above when I get the car back (hopefully today). Any other suggestions would be much appreciated - this car has been with Holden service for a month!

 

[mpower]

i had those symptoms on an LS1, turned out to be O2's.

unfortunately the ones that Holden stock now are garbage and i had to return and replace with something else and all sorted.

that said, it was throwing codes - what if any codes have been read?

 

[rpwc]

thanks mpower. Teh holden service sensor did not look at O2s (I assume these are the ones in the exhaust you are mentioning. I will look into this. I picked it up today and apart from the idle drop I was driving slow behind a queue of cars, when I tried to accelerate - nothing happened at all it felt like it was about to stall, I took foot off the accelerator and then on again and it then worked. This car has been at service centre for a month to be returned with no fix .. frustrating to say the least - oh to answer question on codes - no codes at all - the service guy reckons the vz/alloytec dont report as much as other models and so hard to locate whats going on.

 

[lout]

if it is the O2 sensors
when engine is cold
disconnect battery for 5 minutes, this will reset your fuel trims
then reconnect battery
and go for a drive
before it warms up fully, it will run off the fuel tables which have now been zeroed out
you will only have a minute or two before it goes into closed loop and starts adjusting fuel trims again