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The mkiv Supra Owners Club

Misfire.


tony tt

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With the "feathering" and it only seeming to misfire on WOT/heavy throttle, it definately sounds like ignition failure of some sort mate. It's not unusual for coils and/or plugs to break down when warm and under heavy load.

 

Yeah I know just gettin pissed off. I just want to drive the bloody thing lol

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Looks like the Lambda sensor has croaked, or a wiring issue. Can you read the real time Lambda on a gauge or the diagnostics for the Syvecs? With no Lambda signal it's probably mapped very safe, and to give low / no boost and go rich. BTW, that's not a log, it's just a set of screenshots, a proper log of the fault occurring would be much better.

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Are the yellow parameters in the first picture the faults? If so could the syvecs be creating a misfire on boost to prevent the autobox temperature becoming dangerously high?

 

Old faults apparently Ryan ironed out. There's two tranny coolers on the box. I'll send Ryan the datalogs.

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guess its laptop back in, you drive i'll pull logs then? im just double checking im doing it right.

 

open Sdata, plug in the ethernet cable with the ignition on but don't start the engine, click device, auto read and it will show a ID window, click ok and it downloads it(rename today's date) It then asks if you want to clear the logs and logbook, click yes.

Then file, view in Sview and bingo

 

:)

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guess its laptop back in, you drive i'll pull logs then? im just double checking im doing it right.

 

open Sdata, plug in the ethernet cable with the ignition on but don't start the engine, click device, auto read and it will show a ID window, click ok and it downloads it(rename today's date) It then asks if you want to clear the logs and logbook, click yes.

Then file, view in Sview and bingo

 

:)

 

I should really try this.

 

 

Tony, hope you get it sorted soon bud

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guess its laptop back in, you drive i'll pull logs then? im just double checking im doing it right.

 

open Sdata, plug in the ethernet cable with the ignition on but don't start the engine, click device, auto read and it will show a ID window, click ok and it downloads it(rename today's date) It then asks if you want to clear the logs and logbook, click yes.

Then file, view in Sview and bingo

 

:)

Yep, that's it. Also, if you plug the laptop in and open Smon you can live watch any data you want while the car is running, but you have to set up the graphs. Don't worry though, from that you can't modify or delete the map....that really would be a bad day out! Lol

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If that is the case either the plugs are the wrong type or grade, or you have a serious mapping issue.

 

I've racing 9's coming tomorrow Chris I'll change them over and swap igniters over. I doubt it's the mapping as it pulls really strong till it's quite hot then craps itself on kick down. I'll fit new plugs and hope that's it sorted. If it's not plugs now I'm lost.

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Still to fit the plugs as they haven't arrived yet. I had the car out tonight for a drive and it never skipped a beat for an hour then the miss reared it's head again. Bugger. If it drives on boost with no issues for an hour with a good few kick down pulls I have my doubts it's a plug related issue. Hopefully the plus arrive tomorrow anyway so I'll get them done and start pulling logs for Ryan. It's a bizarre fault.

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Wouldn't hurt to monitor the fuel pressure. The pump could be getting tired after an hour or so.... bit of a shot in the dark, but after reading the thread it's a bit of an odd issue considering what you've changed so far.

 

It's certainly a weird one as it drives great for an hour. The pump is brand new with a 12volt supply bud. Can't really rule it all out yet as I've still the plugs to try but I doubt it's plugs to be honest.

 

AFR's when it's pulling good is around 11.9 but when it misses I'm seeing low 10's.

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Agreed mate. I'd be surprised if it was the plugs as they would fail a lot earlier on.

 

At what RPM does it start missing at? If it's consistent, it could be the ECU safe guarding the engine. Could be a drop in fuel pressure. Either way, I'm dying to know. :D

 

When the miss is on if you floor it then it happens straight away. Wont come on boost but I can feather it in gently and it will build pressure to about 120mph then starts to slightly misfire again. If you drive normally it's a dream and it idles perfect.

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