missing at idle, with AC on

[Nut Kracker]

It may not be missing per se, but labouring too much under load, with the A/C on.
This may give the impression that the engine is missing
When the engine is under load, eg: the A/C on, the ECU recognises this and will command the IAC valve (idle air control)
to open and let more air into the intake, to raise the idle back to normal, therefore compensating for the extra load placed on the engine.
May be the IAC is faulty/dirty and not letting more air in.

 

[diysv6]

Have you tried blocking of the evap solenoid air feed into the inlet manifold?
The evap solenoid could be leaking, stuck partly open, stuck open when hot and causing a loss of idle stability. (VZ doesn't use the IAC valve concept like the VTs)

From a cold start my evap solenoid does not click and the idle is smooth. After about a minute the evap solenoid starts clicking and the idle quality drops off a bit. This then becomes the idle quality for the motor. When my motor is hot, any time I've checked on the evap solenoid it has always been clicking/chattering, evacuating the charcoal canister near the fuel tank.

Added: On checking today, when the AC cuts in there is an idle quality "bump" as the engine ECU takes on the RPM change for the extra AC compressor load etc. This probably impacts on the fact that the evap is still clicking adding pulses of air to the mixture whilst the ECU is catering for engine load. It stabilises back to normal idle pretty quickly 1/3 sec or less.

You could have a cracked hose into the inlet manifold, left side of the throttle body; or the O rings/connectors into and out of the evap solenoid are leaking in unwanted air flow. Checking for a damaged line to the canister would be advisable as dust can enter the inlet manifold and maybe damage the evap and even worse the engine itself.

The evap solenoid appears to have no relationship to the AC being turning on. I have found no indications in any testing I have done, and any documentation I have seen.
It seems to be more a function of the starting system and maybe oxygen sensors being placed into fuel metering operation. Not certain which controls what - the O2 sensors taking over after the start sequence and then the sequence moves onto evap solenoid clicking operation. Or maybe the evap solenoid starts up after a predetermined time period.

 

[exanVZ]

i fixed my problem by replacing the coil packs, I got a set of 6 for about $50 second hand and that did the trick.
sold the car shortly after.

 

[bluedog69]

Have you tried blocking of the evap solenoid air feed into the inlet manifold?
The evap solenoid could be leaking, stuck partly open, stuck open when hot and causing a loss of idle stability. (VZ doesn't use the IAC valve concept like the VTs)

From a cold start my evap solenoid does not click and the idle is smooth. After about a minute the evap solenoid starts clicking and the idle quality drops off a bit. This then becomes the idle quality for the motor. When my motor is hot, any time I've checked on the evap solenoid it has always been clicking/chattering, evacuating the charcoal canister near the fuel tank.

Added: On checking today, when the AC cuts in there is an idle quality "bump" as the engine ECU takes on the RPM change for the extra AC compressor load etc. This probably impacts on the fact that the evap is still clicking adding pulses of air to the mixture whilst the ECU is catering for engine load. It stabilises back to normal idle pretty quickly 1/3 sec or less.

You could have a cracked hose into the inlet manifold, left side of the throttle body; or the O rings/connectors into and out of the evap solenoid are leaking in unwanted air flow. Checking for a damaged line to the canister would be advisable as dust can enter the inlet manifold and maybe damage the evap and even worse the engine itself.

The evap solenoid appears to have no relationship to the AC being turning on. I have found no indications in any testing I have done, and any documentation I have seen.
It seems to be more a function of the starting system and maybe oxygen sensors being placed into fuel metering operation. Not certain which controls what - the O2 sensors taking over after the start sequence and then the sequence moves onto evap solenoid clicking operation. Or maybe the evap solenoid starts up after a predetermined time period.

Did you fix your idle fault, i have the same fault now.

Thanks

 

[viccib]

we had the same issue with ours. we got the timing chain replaced and problem went away. good luck

 

[Silverbird]

Similar symptoms on mine a few weeks ago - ECU fixed it. Going by the thread responses, there a few possibilities for the symptom of 'missing' at idle.

 

[AJS000]

I've got the same Issue with my VE Alloytec SV6. Labours a lot with the AC on.
Connected up oil catch cans to the dumb PCV lines unless there's a leak in there somewhere.
I'll have to check the coils too.
Mechanic told me they have sensors for the coil faults. But if left for a few days if I'm on holiday (like 4 or 5) without running she's a real B**** on start up. Misfiring and all.

 

[danoz vt vz]

we had the same issue with ours. we got the timing chain replaced and problem went away. good luck

I dont think your timing chain did Nothing for the ac.The car would of ran terribly with unserviced or without replaced chains.When it was fixed you had a power gain which gave you a smooth running car even with the a/c on.♤He also said it was fixed with a 60 dollar coil pack.

 

[robgm]

My Commodore 2005 Acclaim was misfiring at idle with AC on, and with AC off but less noticeable, because of the coils. I replaced all the coils and the car is running so smooth (aftermarket coils 6 for $180). Fuel economy improved by more than 1L/100km as well. Original Bosch coils were in the car for 178k/15 years. Also i put 98 RON in (first time ever - to give the system a clean), and the fuel economy is under 11L/100km on motorway. Like i used to get 10 years ago with 91RON.

 

[bushpig666]

I'm hoping I'm close to my issue here. Its fine without air-conditioning on but after you take your foot off the throttle the revs take a long time (5-10 seconds) to return to idle. Fuel economy has also gotten pretty bad. Have cleaned MAF so far with no luck. Will check intake hoses etc mentioned above. Anyone else had the same problem?