Have I jiggered the coil

[dadrathers]

Changed the oil today and to give the new oil a chance to circulate before the engine started I pulled the HT lead off that goes from the coil to the dizzy - at the dizzy end. I kept it out of harms way (i thought) but now the car runs rough at mid to high revs and when you let the revs off they drop almost to a stall and then pick up again. Tickover is OK'ish.

Might I have jiggered the coil by turning the engine over with the HT lead disconnected?

Any other ideas welocome.

[oakgreener]

Surely not. I can't see how that would damage the coil. Have you done some damage to the dizzy cap? Maybe try a new one

[Craigwilson]

it's possible you have I done it once, the 50kV have no where to go while unplugged so it earths to the body via the easiest path, have a look behind the plastic cover on the coil and you'll see if it's cracked

[dadrathers]

That was my worry but tried an old coil that had been working fine before I took it off and same problem.

Also invested in a new genuine vw ignition amplifier still no joy. Tried a different lead from the coil to dizzy and pulled each of the plug leads in turn. Each seemed to have the same effect so not just a single lead I would say. I could feel a good spark as I held them too.

Bit stumped now. Starting to think about fuel - what would be effect of an injector playing up?

[Craigwilson]

could you have knocked the dizzy timing out when youv pulled the lead off if the 13mm bolt isn't tight?

[dadrathers]

In a word - no!!!!

However, having checked out various wiring for splits etc., resistances and voltages I found a loose'ish wire in the multi-plug to the AFM. Pushed that back in and at the end of the evening tried the car and runs fine again. So either it was the loose wire to the AFM or in fiddling I have 'reconnected ' a split wire. See how it goes.

Thanks all for help.