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[tivoom]

Hi im new to this so go ezy i just bought a 1995 vr v6 auto wago first thing i picked up on is a mis at idle iv done a full service including plugs leads coil packs fuel,air,trans,oil filters and new trans and motor oil yet the mis is still there i have done a dio by shorting the 5 and 6 pins in the plug under the steering colium but all 3 sets of flashes were a 12 an all clear in the manual so can some one out there please give me some guidence cos im out of idea's
thanx

[kopper69]

Hi tivoom,

Welcome to the forums. The miss that you have is caused by a cylinder not firing. There is either going to be no fuel getting into the cylinder (ie a faulty injector) or no spark to ignite the fuel.

You have done the right thing by replacing the leads and spark plugs. Both are very common causes of your problem. You have even replaced the coil packs, which is a bit worrying, because this would be the next likely suspect.

It could be the dfi module. Thats the block that sits beneth the coil pack. Take the connector off the side, give it a clean and put it back on, make sure its nice and tight (held on with a bolt). If possible, replace/swap the dfi module. Its a pretty easy job, especially if you have done the coil packs.

I would first work out exactly which cylinder is not firing, causing the rough idle. To do this you need to disconnect the connector from each injector, one at a time. Very easy, simply clips off. When you do this fuel will no longer get pumped into that cylinder and the car will idle very rough EXCEPT on the problem cylinder. Because the problem cylinder is already faulty, there wont be any difference with the injector connected or disconnected. Then you know exactly which cylinder is playing up. You can then measure the resistance of the injector. Should be, from memory, between 14 and 16 ohms. You could also try running some injector cleaner through, it could just be a bit blocked.

Give that a try and let us know how it goes.

[hako]

You could try gapping your plugs down to 1.1mm instead of the recommended 1.5mm - this will allow them to fire easier - the spark having a smaller gap to jump. This costs nothing and cannot do any harm but can sometimes get rid of an annoying miss.
As Kopper69 says, you seem to have covered most of the other angles.

[tivoom]

thanx for the input guys i have just finished (1;30amEDST) the plug gap and the dfi module swap and clean worked a treat ill do the injector test and clean when i wake up as it might upset the neighbours lol so thanx again in ill fill you in tomorrow some time on my results