S1 VVC Misfire Problem on Track day Today

[magarnett]

Suuny day, at Silverstone, having great fun on new Stowe circuit when on second run engine light comes on and misfire starts, meaning i had to pull off. Left for a few mins and managed to start and finish session on short shifting but could feel misfire still there.

Parked up 40 mins and went on 3rd session two laps and engine light on again, big misfire, sounded like running on 3.

Checked
1. plugs - looked ok
2. pulled HT lead on 1 & 4 while engine running and not much different in running.
3.pulled HT lead on 2 & 3 while engine running and running got worse.

Fiddled around with all leads and eventually gave up and decided to set off home. Well BUG..r me she runs fine. Next session she runs fine but session after same misfire again.

After some fiddling with cables near coil packs and HT leads and 1 hour to cool managed to get her running. Ran fine all the way hone 100 mls at 3-4000 revs........... arghhhhhhhhh

Suggestionsa anyone???????? Coils or HT leads or both..... anything else?

By the way car is 1999 S1 VVC and the coils and leads are all as fitted at factory when new.

Regards

Mark

[Justin S]

I think you may have answered it yourself, 11 yr old HT leads is a good start. I change mine every cambelt service, so every 4 years....................

[Xracer]

I have just repaired an S1 111S with the same problem for a customer. The car is fitted with twin coil packs which fire in pairs 1+4 & 2+3, although each coilpack fires two cyninders, only one was affected replacing the coilpack cured the problem. You can diagnose by switching which coil fires which cylinders & see if the misfire moves with it, if it doesn't move most likely leads. HTH
Ian Jude

JPSautocare

[Sumshi]

I ended up on a 111s 1999 changing the plugs , then the HT leads , then the coil AND replacing the new plugs before the problem went away. However I think I had 2 problems one after another which would explain the plugs. 54k miles