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Discussion Starter #1
i cant seem to figure out what the hell is going on wit this.
when the air temp is cool out(night time or now that it is winter) my car(1jzgte in a a70) will pop and cut out harshly for a fraction of a second at wide open throttle around full boost. i dont think it is fuel cut because i hooked up a boost gauge to the 1jz wile it was on a dyno. the most psi was 7-8 and then it cut out. thinking it was a misfire i changed my plugs to denso iradium 5304's gapped to .30. this did not solve the problem. the only mods i am running are intake,trust 3inch DP, 3"test pipe, cat back exhaust. this problem does not happen when it is warm.the car will rev to redline just fine if it is at 3/4 throttle(cold out) but not @full boost.
 

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im gonna have to say check all your ic piping for cracks and stuff, sounds like a pretty big boost leak...are you blowing any black smoke under boost or when you misfire? There also could be problems with the ecu reading density of the intake air(as you said that it was cold outside = more dense air), although i have no idea what sensor that would be on a 1j. check codes(again...if it can be done on the 1j) and go from there.

adam
 

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HMOOB VWJ NYOB MINNESOTA
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Mine does the same too:( at full boost. Boost bounce up and down between 19 and 25 psi.

see pix:


I regap my plugs to 26 and it help a little but not a lot. Im going to get a new set of plug coil and see if that'll fix the problem. If you figured it out before me then do share too:)
 

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I have the same problem too. When its warm I can use my Profec B and put the low boost at the middle between high and low. The boost will just shoot up real fast. I didn't have boost gauge back in summer but it will go far above stock gauge. Now when its I hardly can use my Profec B. I tried to put at the 3 line still the same problem. I just bought blitz DTT and when I tried to use the Profec B my max boost was 0.75 bar. Now i just turn the Profec B off and use my shim wastegate. It boost so slow compared to Profec B. I tried to find any boost leak but no luck so far.
 

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Discussion Starter #6
does this happen only with cooler weather to you guys too?
could this be a faulty map sensor?

PS> your a/f ratio looks a little low.
 

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Does the 1jz have seperate coils for each plug like the 2jz? The reason I ask is I have had this problem with SR20DET's and VG30DETT's and it be coils breaking down at high boost pressures in colder weather causing problems.
 

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Discussion Starter #8
yes they do sport the individual coil packs. you have had the same problem with nissan? same symptoms? new packs fix it?
 

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boost freak
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i would ditch the iridiums and try a copper plug a heat range or two colder than stock and gap 'em down a bit. its possible the irid plug is staying too hot and pre-igniting your mixutre...
 

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Discussion Starter #10
when i changed the plugs out(3days ago) the previous plugs were Nippon Denso platnium; gaped around .30-.32. Would this help to identify the problem?
what kind of copper plugs are offered in the market? is this a common fix for my symptoms? would the plug really stay lit for another stroke(combustion>exhaust) only under full boost with dense air?
 

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I don't know it happen when I am using copper plug from Autozone. When I pulled the plug out it was covered with gas.
 

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Discussion Starter #12
my plugs were all gooped up too. i think it was just what was built up on top of the plug; when i took them out it drained onto the plug itself.
 

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Discussion Starter #14
man, i hate to think that i wasted 70 clams on som plugs. how long do you get(life) out of the copper plugs?
any other ideas why this is going on??????????
 

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Discussion Starter #16
JONEZ do you have a 7M or a 1jz?? do you run copper plugs? if 1jz what specific plug do you use?
 

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Discussion Starter #17 (Edited)
well i pulled the codes today. i rang up a 14 and 34.14=ignition signal34= turbocharger prerssure abnormal.HMMMM> ill try to look up the first.....
 
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