[J.Wright]

I've read plenty of thread about misfiring but can't seem to find a situation exactly the same.

Basically, I had a misfire, changed spark plugs and coil pack, problem solved...no 2 weeks later and I have another misfire.

When idling it sometimes seems to run fine, sometimes it's really rough and sounds like it's about to stall (I can feel the engine rocking on it's mounts through the pedals). When driving, if I only lightly press the accelerator it seems fine, with only the odd misfire, if I put my foot down it misfires so much so that it sounds like a machine gun!

When it's idling rough I have tried taking each HT lead off to identify which cylinder is misfiring but each one seems to make it worse, so I have been unable to judge.

I'm pretty happy to change as many cheap parts as I can before resigning to getting a diagnostics test, it'd probably workout cheaper that way and new parts can never be bad.

Hope someone can help, thanks.

 

[stupotasaurus1988]

are the plug leads and king lead ok?
you say you changed your coil pack? correct me if im wrong is the 1.2 not on a dizzy cap and rotary arm? are they ok?
we are talking mk1 1.2 here arnt we?

failing that have you got any warning lights showing up?

 

[ady1234uk]

did you replace all the coils or just one of them when one go thay all go not long later or thay have on me

 

[J.Wright]

It's the D7f engine, it's a coil pack, 2 coils in one block. I changed the whole pack and it was fine for awhile.

If I take the plug out, put it in the lead and run the engine, each one is sparking.

No warning lights are showing up, the toxic fumes light stays on for about 5 seconds when I start the engine but it never shows whilst driving.

I keep meaning to adjust the valves as they are bloody noisy and I hope this may make some sort of difference, I've heard that sometimes the exhaust valves get a bit tight and this can cause a misfire, not found the time yet.

 

[ady1234uk]

have you got a pressure testing kit i had a scenic once that was down on pressure in one cylinder runned fine at slow speeds but when you went on a moterway it went bang bang bang all the time till you slowed down