Rough idle - what could it be.

[shane_3800]

I didn't think they had an idle solenoid but a stepper motor, not sure about it though The idle is rock solid on 600rpm, car just shakes. I think could be coil but not sure how to go about testing them.

The problem with many mechanics these days they didn't learn old school diagnosis, they just plug the diagnostic gear in and if it doesn't see the fault and tell them what to replace then they have no idea. I don't want to take it to a workshop for them to waste hours on it and charge me for loads of parts they've put on it trying to find the problem.

I'll do a bit more stuffing around and head scratching on the weekend

im a young mechanic i hardley use the scantool i have been learing how to use gas benches and scopes but it is all to do with feel my boss can just say check this and bang that is usally the prob

most rough idles i have seen are spark plug or coil related

and yea i meant stepper motor

 

[LittleMissVE]

hmm my car idles at 550ish when its warmed up.

its my first v8, thought they all idled low?

Mine idles around 550 too... I read this yesterday & had to check this morning cos I've never even noticed.

 

[Michelson4301]

These things are FBW so no stepper motor. Coils are a possibility but it would be very obvious if a coil was dead or dying under full load as the increase cylinder pressures would take more coil voltage to jump the spark gap.

All V6 motors released in Holdens (I can't speak for other brands/countries) are inherently noisy and harsh. It is due to their design "flaw". I would suspect a sagged engine mount if they have been subjected to oil or you have highish kays ie. 80,000km+.

 

[VECom]

I did notice there was no throttle cable on it. How high tech the old commodore has got.

Under load it runs fine and it's as smooth as a bommodore is. Engine mount now that's a possibility. 104k so if that's a known problem then something worth checking. I'll jack the engine and see what happens.

 

[masmith]

Could be the Mass Airflow Metre my o8 VE did the exact same

 

[Jake96]

My 08 ve with 129ks has started being rough on idle but runs fine. Did anyone find out what the problem was?