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The mkiv Supra Owners Club

Misfire


AlexM

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I'm having some misfiring issues on my TT, which have existed since I had the car serviced & mapped about one month ago..

 

Symptoms:

At idle there is an occasional light misfire, sometimes it's there, sometimes it is not.

Under light throttle there can be a misfire at varying points through the rev range, I've seen it happen at 2,400rpm, 3,500rpm, and a few other spots. I cannot always reproduce it but it tends to appear when I least expect it (usually when I'm just starting to think I've fixed the problem!).

Under full throttle there is a misfire above ~6,200rpm, for some reason this seems to be slightly furthur up in manual mode.

 

Storyboard, Actions & Results:

Due to a misunderstanding my spark plugs were not changed/checked when the car was serviced, so they were swapped over first. This seemed to make the top end misfire disappear.. but it came back shortly afterwards.

 

Coil packs were swapped over in pairs next, with the third set causing the car to run absolutely perfectly. Extremely happy I parked the car up for a bit, came back to it an hour later.. and all the problems were back. :lamesign:

 

Ryan put £5 on it being the coil pack connectors (which had pretty much disintegrated when the coil packs were changed). I followed Ian's guide and refurbished the lot, tweaked the metal tab and changed all the plastics, reconnected. Went for a test drive, and the car was perfect.. for one run (see where this is going?).

 

Unfortunately frustration got the better of me here and I went and ordered a full set of replacement coil packs, just to be sure. Changed the lot over yesterday (to PHRs Super Spark) and started her up. The slight misfire at idle was there, however I went for a good drive and couldn't get the full or light throttle misfires to appear, which seemed promising..

 

This morning.. I have a misfire. :stickpoke

 

 

What do I look at next?

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Most of it is fine, there's a slight cut in the insulation on a wire going to the first coil - wire itself looked fine so I just put a little electrical tape around it.

 

I'll see if someone has a good ignitor pack I can borrow for a week..

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