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VZ V6 Erratic Engine Running

RonG

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I all Alloytech Guru's. I am having issues with my 05 VZ Commodore V6. Erratic engine running.
It is a base model with the Alloytech V6
220k's
Automatic

For some time, it has had a problem with a misfire under load (aircon on etc). I have changed the plugs and that did seem to help for a few months.

The problem has returned, but now is far worse.

At idle it is very rough and came up with a driveline error code on the display. Using a scanner, it indicated low pre cat O2 sensor voltages. So i replaced both of them. Still the same problem.

The strange thing is when I rev the engine, it is very erratic. Sometimes it wont rev past approx 3000, other times it feels like its normal self.

Looking at the scanner, the Ignition advance is all over the place, from -15 to +25 degrees.

I am not sure what to do next. Could it be one of the angle sensors - or is it time to shotgun the thing and replace plug ignition coil packs, plugs, injectors etc.

Thanks for your time
 

greenacc

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Have the coils ever been replaced? I'm thinking they might be the issue. Also check all the sensor plugs around the engine. I had corrosion in my air flow sensor plugs that gave strange symptoms
 

Wats_in_a_name

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Whilst I don't want to lead you on a wild goose chase and say throw money at this or that I would suspect that coils are a very good bet. Others on the forum might be able to give you tips about which coil in particular is playing up. Last year I replaced coils. Symptoms were having a sudden stutter under load. If it was injectors this would most likely throw a code. I had to have one of them replaced a couple of years ago.
 

RonG

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Hi greenacc and Crowny,

Thanks for the reply. I shall give the coils a go and see what happens.
 

RonG

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Hi greenacc and Crowny,

Thanks for the reply. I shall give the coils a go and see what happens.
Hi Greenacc and Crowny.

Had the coils tested - most were dead. So got new coils and plugs.

Also had a problem with overheating - so decided to do the thermo at the same time. That delayed things no end.

Started it up, still not idling well - so changed the fuel filter (hadn't been done for ages). This fixed the idle issue.

Now I have the VZ back! Lots of power etc.

Thanks for the advice!
 
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