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The mkiv Supra Owners Club

Misfire help


JayJay1374

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Hi everyone. Currently having a misfire problem and it's getting the better of me. Misfires on boost over 1bar, bpu car running 1.2 normally. If I control the throttle and don't go full throttle it's ok as long as it's below 1 bar.

 

So late last year I developed a misfire running ngk bkr7eix plugs. Fast forward to this year and I still have the misfire (the car was off the road over winter).

Anyway so I changed the plugs for a set of BKR8EIX and alas the misfire was still there. But it was different. The misfire seemed to stay between 3500-5800 rpm then pick up as normal after. So I went to fueling next. The car has had the 12v fuel pump mod done with a relay. To rule this out I removed the relay and returned to standard. I also changed the plugs to denso ik22's so I'm back in the 7 heat range.

 

So the misfire disappears. Awesome! Well it returned a week later. So I've checked the plugs (seem ok). Tired my old bkr7eix in and still a misfire, checked all the wiring I altered removing the 12v mod. All ok. I've changed the fuel pump ecu. Again no change. I've even tried changing the fueling back to 12v and still no change.

 

I want to get a multimeter on the pump and make sure it's defiantly getting the correct 9v at idle and I will bridge the obd port to check the 12v supply.

 

Have I bought the wrong plugs? Ik22's?

 

The only thing that changed was the plugs and 12v mod.

 

Any help or advice is appreciated.

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The "clips" are just the plastic body holding the actual terminals, have yiou cut back a little way into the coil pack loom and fitted new terminals that you can buy from Toyota with factory crimped on wire tails? I would do that next, and if there's no improvement get the HT traces looked at on a scope, unless you feel lucky and diagnose by throwing bits at it ;) The coil loom terminals should be considered service items these days.

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Chris I did fit replacement terminals when doing the clips as my wiring looked worse for wear.

 

Ok so I have borrowed a known working set of coilpacks of safcdixon and it runs perfectly. No miss at all.

 

So next port of call is to swap 1 coilpack out at a time to see if it's just 1 or a mix of a couple and after that source replacements.

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Chris I did fit replacement terminals when doing the clips as my wiring looked worse for wear.

 

Ok so I have borrowed a known working set of coilpacks of safcdixon and it runs perfectly. No miss at all.

 

So next port of call is to swap 1 coilpack out at a time to see if it's just 1 or a mix of a couple and after that source replacements.

 

Good to hear it's fixed and not surprised it's coil packs but would suggest you renew them all if you can.

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  • 2 weeks later...

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