Rough idle and tacho jumps slightly

[jesse'sVT5.0]

Hi All,

I am searching for the answer to this but so many people have had similar issues and so many different fixes so I am asking the VT boys and girls... Here we go.

I cleaned the MAF sensor and installed a K&N panel filter at the same time. It was fine for a bout three weeks... Until I have noticed the following over the last three days.

When cold (over night or not driven for a while) I start the car and the idle has become rough. While it does this I have noticed the tacho needle jumps in time with the shudders. only by maybe 100-300 odd rpm.

After 5-10 min of driving it will settle down. I will take the car for a service soon but tell me, anyone had this small issue before, can anyone point me in the right direction?

Thanks,

Jez (going back to the search function for more reading).

[accentstencil]

You could try cleaning the IAC valve (idle Air Control valve) with carby cleaner or throttle body cleaner, this can often help. The IAC valve is on the throttle body.

[And_ROOS]

I have the same problem, usually when my car is idling the revs will drop, the car shudders, the revs shoot back up. When driving or not idling for very long its ok, but say you get stuck in traffic or a drive through and thats when it happens.

[drift-it]

probably not the problem but if ur using a k&n oil based filter try cleaning the air flow meters heated wires with a electrical contact cleaner...oil mist can accumulate and give false readings...

[KegRaider]

Hi Jez,

I experienced similar about 12months back. Replaced my spark plugs and plug leads and the problem went away.

You could just have come crap in one of your spark plugs. Pop your bonnet, and start the car.
Remove one plug lead and if the engine becomes rougher, that is not the culprit and replace the lead. Move to the next lead and repeat. You will probably find that you get to one lead/spark plug that makes no change in the idle roughness. This will be the problem child.

Have fun, and watch out you don't get belted by the voltage from the coil, that stings...hehe.

[jesse'sVT5.0]

Thanks for the responses,

So far I have tried cleaning and re-fitting the MAF Sensor. I added injector cleaner to the tank in the hope it might help, at least it can't hurt.

I have tried the spark plugs as you suggested Keg but I could only get six of the eight. Will try the others when I have more time.

I'm going to take it to my mechanic cause I just don't have the time. I downloaded the Holden manual too, good for a read.

Thanks.

[jesse'sVT5.0]

Hi,

For anyone interested it turned out to be a burnt spark plug lead. Spark plugs were pretty bad too. Changed and running fine, now have a clean bill of health.

Cheers!