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The mkiv Supra Owners Club

Misfire at high boost. Can’t get rid of it


bayside_supra

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Hi everyone

 

I have had a misfire at high boost for about 6 months. Car runs fine off boost and perfect at 1.5 bar. Turn it up to 1.7 bar and it misfires on full throttle from about 5k upwards.

 

So far i have replaced spark plugs, coil packs, and the whole coil pack loom, all with brand new parts. No real change apart from it was misfiring at 1.5 bar as well before the coil packs were replaced.

 

It started shortly after I had my engine dressed but I think we have addressed everything that could have caused it from that now. The only thing we haven’t touched is the adjustable cam gears I had fitted fitted at the same time. Darren @ magnum performance says this is unlikely to be the culprit and they were only for looks anyway so no adjustments to timing have been made.

 

Any ideas?

 

 

 

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What plugs are you running, and what have you gaped them too?

 

Any idea on what your air fuel ratio is whilst boosting at 1.7 bar? Any idea what fuel pressure you are running during boost?

 

Ngk iridium 8s.

 

Not sure on air fuel ratio and I have no sensor, but I can have a look at the toucan next run to see the fuel pressure. I need to do a Syvecs log to send to Romain, just haven’t had a chance yet.

 

 

 

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Only just recently driven the car again to try and get to the bottom of this. Replacing the old oem coil packs with Whifbitz ones didn’t seem to make any difference. But they are advertised as being stronger and producing a higher spark. Are we saying they don’t?

 

I have now sent the logs off to Romain, I will get him to check the fuel pressure.

 

 

 

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