engine break-up at 29.99 psi ? (gt4578)

scott2298

New Member
Dec 26, 2009
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florida
we were able to produce 981 rwhp with 38 psi of boost. took to track and was not able to exceed 30 psi no matter what i did. I changed the plugs, ran new grounds, changed the mapping sensor (5 bar) did not help,no feul pressure change, replaced alt with 150 amp alt voltage all the way up to 8000rpm is over 13v. please help!!!!!!!!!!!!!! pics and dyno video are in my profile.
 

scott2298

New Member
Dec 26, 2009
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florida
any rpm it seems to be as soon as i hit 30 psi i can set my AEM tru boost for 28 psi and will run perfect at any rpm 2jz
 

IJ.

Grumpy Old Man
Mar 30, 2005
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It "might" just be simple spark blowout as the real world loads an engine more than the dyno, I'd try dropping the gaps and see if it improves keeping in mind NOT to touch the centre electrodes as they're easily damaged.

First things first though pull a plug as see what the gaps are now.
 

suprahero

naughty by nature
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Aug 26, 2005
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IJ.;1545645 said:
Knock em down to 22 and see if it improves at all.


28 seems way high for that amount of boost. I was only running 23psi of boost and I have to run .020 gap. I now have the 1zzfe coils and I can run about .028 gap, but not with irridiums. My car wouldn't run hardly at all at high psi with irridiums.
 

RacerXJ220

Interdimensional
Mar 30, 2005
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Abalama
suprahero;1545658 said:
28 seems way high for that amount of boost. I was only running 23psi of boost and I have to run .020 gap. I now have the 1zzfe coils and I can run about .028 gap, but not with irridiums. My car wouldn't run hardly at all at high psi with irridiums.

Word.
 

IJ.

Grumpy Old Man
Mar 30, 2005
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scott2298;1545768 said:
the car wont start with the plug gap at 22 ?

Can't think of a reason it wouldn't...

I had a few issues with IR plugs in my 7M when I got around the 30psi mark it used to glowplug a bit and run really ragged changed to coppers and it went away, didn't mention it as I didn't think it relevent to a 2J but after J's post it could be worth a try.