t5 missfire problems

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tirediron
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t5 missfire problems

Postby tirediron » Sun Jul 03, 2016 5:16 pm

I have been having some issues with one of my t5 converted race cars.

it has not always been like this since I converted it, ran a few races with no problems.

once the car gets hot, it has a lack of power/ misfire under high load/ high rpm that appears suddenly and progressively gets worse.

I wired in a dlc connector because I did not previously have one- no codes with a generic reader.
have changed- DIC with multiple units, crank sensor, adjusted trigger wheel, checked fuel pickup, drained and filled fuel tank with fresh fuel, ecu.

nothing had any effect. hard to describe why, but I believe to to be ignition rather than fuel. it really feels like the timing is too far retarded when this happens (may not be timing related at all, just how it feels when the concern happens).

ive been throwing parts at the thing because the concern is very hard for me to duplicate. it will idle and free rev for hours just fine in my driveway, and I cant do enough wot pulls on the road without getting arrested for it to act up.

thoughts?
-matt

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squaab99t
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Re: t5 missfire problems

Postby squaab99t » Mon Jul 04, 2016 11:17 pm

What level of boost are you running?
Have your pulled the spark plug, what gap?
What is the timing with a light at 2500? Does it match what the ecu is seeing with T5 suite?

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Jordan
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Re: t5 missfire problems

Postby Jordan » Tue Jul 05, 2016 5:01 pm

I don't think he is running ANY boost.

Degradation when hot sounds like a hardware problem.

I recently had the same issue at the last Palmer race. It was a miss that felt like it wasn't getting enough fuel and you could sort of drive around it with throttle changes. A change of plugs and new DI and it went away. It was weird, it would only happen in very light throttle situations after a lot of hard braking and only when you were running really hard. It was also very slowly getting worse. It just appeared and then in the same spots on the track would pop up again.

If you have already chased those, then you really have to do some other other basic tests, fuel pressure checks, vacuum leaks (less important on T5, but who knows) , bad injectors, and the other sensors. Temp related could be Air temp or Coolant Temp. If you have the ability to turn off the car without a kill switch and you have the check engine light plugged in you can also check/pull codes right from the t5 flash sequences. If you kill battery to the ECU all codes will be reset as well.

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DrewP
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Re: t5 missfire problems

Postby DrewP » Tue Jul 05, 2016 8:01 pm

I'm with Jordan. Make sure there are no vacuum leaks, and that you have a good vacuum signal hose to the MAP sensor, no cracks or anything. Bad IAT sensor might cause it too, but those very rarely go bad.
"You can educate ignorance, but you can't fix stupid."

tirediron
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Re: t5 missfire problems

Postby tirediron » Tue Jul 05, 2016 9:20 pm

sorry I should have specified. zero boost, N/A car.

haven't changed the plugs, but they looked ok. ill thow a set in anyways, but like Jordan suggested I am thinking hardware issue due to it being temp related.

I did try unplugging the IAT. I am not sure what T5 defaults to in that case, but there was zero change. wouldn't stay running at all unplugging the coolant temp sensor, so that's a possibility. also TPS crossed my mind, never heard of a bad one though. ill do some more basic checks. I just haven't gone after a fuel pressure issue because it didn't feel like it.. and I thought T5 didn't care about vac leaks.

dennis- I don't have T5 suite capability so I originally just set the CPS trigger wheel in the middle of the slot. seemed ok for a few races. when this issue started I tried moving it both ways with no noticeable effect, concern still present.
-matt

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DrewP
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Re: t5 missfire problems

Postby DrewP » Wed Jul 06, 2016 11:06 am

TPS is easy to check.

Not sure about unplugging IAT, but when you unplug the connector to the MAP sensor I believe it defaults to a TPS-only mapping, so that might tell you something.
"You can educate ignorance, but you can't fix stupid."

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Jordan
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Re: t5 missfire problems

Postby Jordan » Wed Jul 06, 2016 11:48 am

MAP and IAT are probably the most important sensors for determining mixtures, as they determine the air mass. Ignition is based on MAP and RPM. TPS is really only used for enrichment/enleament.

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DrewP
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Re: t5 missfire problems

Postby DrewP » Wed Jul 06, 2016 4:21 pm

I need to do some enleanment to my tummy...
"You can educate ignorance, but you can't fix stupid."

tirediron
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Re: t5 missfire problems

Postby tirediron » Thu Jul 14, 2016 7:26 pm

while I don't really want to admit it, I think I found my problem.

crank pulley bolt is loose. which obviously causes CPS issues with a crank pulley mounted CPS. why it only surfaced when hot, i'm not sure. coincidence maybe.
-matt


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