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The mkiv Supra Owners Club

Can excessive engine heat cause missfire


jevansio

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My Supe has a missfire from hell at the mo, sounds like a scooby with lairy cams.

 

I'm trying to recall what I may have done before it started I one thing I did was remove the heatwrap from the manifold. Since doing this when I pull up I check under the hood & it's roasting. Could excessive heat cause an ignition problem (premature coilpack breakdown etc).

 

Also my manifold is blowing slighty (where it bolts onto the head). Can this cause a missfire.

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Excessive intake temps can cause det, depending on the ECU it can be setup so that it pulls timing which could feel like hesitation etc.

I don't think it's det, it sounds/feels like a proper miss, I'm going to swap my coilpacks with Michel to elliminate them 1st I think, typical, car has been running mint for ages, TOTB nears & it starts spitting it's dummy :rolleyes:

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I'm fairly sure heat killed 2 of mine in Germany racing a pair of RS6s at 180... it was one of the hottest days of the year and my car first developed a miss before 1, then 2 cylinders stopped firing altogether.

 

The car was fine up until this point.

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I'm fairly sure heat killed 2 of mine in Germany racing a pair of RS6s at 180... it was one of the hottest days of the year and my car first developed a miss before 1, then 2 cylinders stopped firing altogether.

 

The car was fine up until this point.

What I'm worried about is diagnosing the problem to be the coilpacks, shelling out £400 on new ones (before I get my manifold wrapped) and the same thing happening, that's if it is the heat that has caused the missfire.

 

My car has been running fine for ages (engine wise) before this

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Ian R had similar sounding issues on his previous single when we were on the way to the 'Ring 2 years ago. The car was fine when cold, but after a blast and then sitting in traffic/slow roads the theory was that there wasn't enough airflow to keep the underbonnet temps down and I think it was old coilpacks that were suffering as a result.

 

Ian had it all diagnosed when we got back hence I'm not 100% sure. IIRC the car was fine being thrashed at high speeds, it was mainly afterwards when pootling that it had issues.

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Logically, i wouldn't thought it would be a heat issue, unless your seeing high oil and water temps as well, the coil paks could just be suffering from old age/weakness, as they are designed to withstand high temps, or they wouldn't have used individual coil on plug set up;)

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What I'm worried about is diagnosing the problem to be the coilpacks, shelling out £400 on new ones (before I get my manifold wrapped) and the same thing happening, that's if it is the heat that has caused the missfire.

 

My car has been running fine for ages (engine wise) before this

 

Would something like a TRD bonnet help you there Jay? Could be beneficial in getting the heat out?

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Sounds familar, my AEM had been playing up as one of the pin connectors to it was slightly loose. So I could get a week of flawless driving and then all of a sudden or sorts of odd things would happen. One such thing with a huge misfire that sounded like a Scooby on wild cams.

 

Until Ryan found what was causing all these problems, I always managed to 'sort' them by pulling the ECU fuses out for a few secs, maybe worth a go.

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Well I've sorted the missfire, turned out that I went along each of the coilpacks & pushed the pin down so it would make a better contact, it went straight away, been out boosting @ 1.6 BAR & not a sign :D

 

But just as I shouted yippie, a big swoosh & I lost all boost, sounds like a pipe has popped off, I had a quick look & couldn't see anything obvious, I guess I'll have to go over each joint one at a time. Do problems ever end on these cars :D

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:D

 

I had a good look again & couldn't see any loose clips or splits so I decided to take the plunge & remove the front bumper & entire FMIC & piping (it gave me the chance to remove the AC condenser aswell).

 

Checked the FMIC 1st, no leaks, then the FMIC to throttle pipes, again no leaks, then the compressor to FMIC, 1 massive leak (see attached).

 

So at least I've found it & the car is running well :)

IMG_2591.jpg

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Nice one J. That is a large hole. :D

Cheers Andy, you should have seen me & my mate checking the pipework, we each had one end over our mouths & were blowing as hard as we could, people must have thought we were nuts :D

 

Oh to test the FMIC I filled it with water, I'm letting it drain overnight, is there anything I should be concerned about after filling it with water?

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Great to see you getting involved Jay and enjoying it.

 

Sorry couldn't see you today but im glad you sorted it.

 

Ryan

Cheers Ryan, yeah I had a lot on today, fixing the Supe, finishing decking out the back, plus loads of other stuff, will catch you next time

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Cheers Andy, you should have seen me & my mate checking the pipework, we each had one end over our mouths & were blowing as hard as we could, people must have thought we were nuts :D

 

Oh to test the FMIC I filled it with water, I'm letting it drain overnight, is there anything I should be concerned about after filling it with water?

 

Just let it dry completely mate. :) Got a great image in my head of you two blowing through pipes. :D

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Why not put a proper intercooler in there now while its out :D

I may do, 4-Row should be here shortly, also my new CF front lip will be easier to fit now the front bumper is off, so all things point to me waiting till the weekend.

 

Trouble with that is that's 1 week of driving (test time) before TOTB which. I don't really want to have a load of stuff wacked on the car unproven "just" before TOTB

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