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Missfire at idle...

Sorak

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Hi all,

I am new to commodores and also to this forum, I am hoping someone can help me with this...

I've just bought a VS, and the engine occasionally faulters when idling at traffic lights, otherwise it runs well...

It has new plugs and I've just replaced the leads. When I recently got the Auto serviced they reported the following codes...

23: Air intake temp voltage high 2/255
75: System voltage high 4/255
76: Short term fuel trim delta high 6/255

Could code 23 or 76 cause this prob?
Any help would be much appreciated...

Thanks,

Paul.
 

HsvPlayBoy

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check the Harmonic Balancer if its cracking then this will cause the missfire and also check things like the Fuel map sensor & the Crank angle & oxy Sensor maybe one of these Things or even a Dirty throttle body Good Luck Man
 

Sorak

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Thanks for your quick reply HsvPlayBoy. I will check these when I have the time. Is there an easy way to check the Harmonic Balancer?

Could the air intake temp sensor also cause a missfire?

Thanks...
 

protossw

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same problems with my VR,,,
 

hako

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Check that the new leads are pushed properly onto the spark plug caps - sometimes they arent on full and this can cause a miss. The harmonic balancer should not cause a miss....usually its a clunk/bang as it fails. Good luck
 

Sorak

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Thanks, I have checked the leads and they seem fine.

I've also cleaned the throttle body and IAC and have replaced the air intake temp sensor. Last week I started running BP ultimate to hopefully clean the injectors.

Could code 76: short term fuel trim delta be a cause? Maybe the injectors or O2 sensors?

Thanks.
 

bradcad

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i found a lot of the time with fuel injection it can be caused by vaccuum leaks- even oil leaks. If this is the case, taking a day to clean the motor down and fix all oil leaks, tighten all hoses etc can help

failing that I use a top fuel additive which cleaned mine right up..
 

immortality

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it's a common problem on the ecotec series of engines forthe little purge hose under the TB to come of, this normally presents as a rough idle and excessive fuel usage as your fault codes show. get someone to check the voltage output of the altenator also as you have a high voltage fault code also. once you have done these things have reset the ecu and then se if the fault codes return, good luck.
 
V

VS Roy

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I Think this problem is very common in the V6s especially because Beuik origonally desighned this engine to be a 5.0 V8 and they choped the rear 2 cylinders off to make it a 6. This meant that it would produce a macive vibration because the angle of the block was set up for a V8 and not a 6. To stop this vibration GMH bored a hole at the top of the camshaft and fitted a balance shaft, they also used oil filled engine mounts to help adsorb the shock. There are ways to help reduce this miss but it can never be compleatly eradicated.
I would be putting in MSD blasted coils to give it a stronger spark, Take the injectors out to get them cleaned by a ultrasonic cleaner and replacing the leads and plugs. Also go through the computer and fix all fault coads.
 
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