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Loss of power/misfire under boost @5K rpm
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Old 27 Jan 2012, 03:19 AM   #1 (permalink)
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Loss of power/misfire under boost @5K rpm

Hi everyone,

I have a ver2 STi and have been having a couple issues with the car falling on it's face at about 5K rpm. I'm using a Greddy profecb spec2 EBC which was working good until just over a month ago.

I was on the freeway and went through a number of pulls to check my AFRs and went shopping for christmas.
On the way back home, I was overtaking a tractor trailer and when I hit 5K rpm under boost, the car began to have 1/2 sec lapses of power. It felt like fuel cut but my WBO2 shows no leaning of fuel.

Since then, I have changed my Walboro to another Walboro 255, installed a new fuel filter, checked all my vaccum lines, checked my plugs and gaps (running 7 series NGK iridiums at .028"), and also checked my gaskets at the up pipe and down pipe for leaks.

Today I changed settings in my EBC and adjusted my wastegate tension 1/2 turn tighter. I took it for a run in 4th but the car completely falls on its face at 5K rpm. I am running a Synapse Recirc, TD05 18G, FMIC, TBE, Sard 800, stock FPR, Apexi PFC, Z32 MAF, and a Greddy Profec b Spec2 EBC.

Most of the tuning I have done myself (There are no tuners within 1200kms of here) and the car was running good for quite sometime so I have no idea why this is happening.

Any suggestions???? Also was wondering if someone could look over my maps/datalogs and give some input or do somekind of online tuning??

I've tried North American sites but everyone here (including my budddies) all have the new age w/ Access ports. Please help with this problem. Much appreciated.
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Old 28 Jan 2012, 01:33 AM   #2 (permalink)
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Re: Loss of power/misfire under boost @5K rpm

I tried resetting the Apexi with the black and green connectors and the stumbling went away when I took it for a test drive last night.... but....today when I took it on the freeway the stuttering began again. tried adjusting the EBC but no change. I pulled over and reset the ECU (black and green connectors) and voila!! The car ran to redline without a hiccup.

What could be causing this?? I have no CEL or codes.
Anyone have a problem like this? The EBC is atndalone so why would resetting the ECU correct the problem and why would it reoccur?

Any insight appreciated.
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Old 28 Jan 2012, 01:33 AM   #3 (permalink)
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Re: Loss of power/misfire under boost @5K rpm

My guess is it needs the map looked at, thast alot of mods to be running without being remapped for them, sounds like you might need a mapper to come to you.
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Old 28 Jan 2012, 02:06 AM   #4 (permalink)
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Re: Loss of power/misfire under boost @5K rpm

Yes I would like that but cannot afford such luxuries

I don't believe it's the map cause I had it tuned about 1.5 yrs ago (4wheel dyno) but I had to drive 1200kms and stay in a hotel and.... it was very costly and I can't afford that for a while. That tuner also wasn't too fond of the Apexi ECU, no one around here want's to or knows how to tune an Apexi pFC.

This summer, I'm planning to go to a reputable tuner who is 1500kms away but I need to save up for that cause it's going to be a 5 day journey. Anyways I believe its mechanically related but was wondering if anyone has experienced this before.

Thanks,

Brian
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Old 30 Jan 2012, 12:13 PM   #5 (permalink)
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Re: Loss of power/misfire under boost @5K rpm

prob best to wind the boost way back till then, better to have it slower and runnign safer than risk needing a new engine.
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