1jz single breaking up under boost :(

[1wickedA70]

got my single 1jz running decent except for the part that it breaks up in high rpms. from around 5500 sometimes 5000-7500..i gapped the plugs to .020, i knw its really low but this is where i had to gap them to stop my stock twins from breaking up. i also checked my coil stems for cracks, didnt find any but i still covered them with electrical tape. any suggestions? do you think maybe i should raise the plug gap?

 

[OneJArpus]

check the resistance in the coils and see if they are with in spec. Try different plugs. Get a DLI unit to help. just a few things i can think of

 

[super.secret.supra.club]

how much boost?

look closely at your plugs they might be cracked

 

[TripleC]

Dude i suggest changing your gap to .028. That is where mine is and i was having the same issue. I also would check for a small boost leak

 

[suprahero]

I doubt raising the gap is going to help him with his problem, but it won't take but a few minutes to eliminate that as a problem or confirm it as a fix. How much boost are you running? I had to add a HKS DLI to mine when I was trying to boost 22psi with a pt67.

Make sure you read the "Similar Threads" down at the bottom of this page to make sure you've tried all of the other suggestions. Good luck.

 

[S.A. supra]

I had a problem like that I epoxyed the coil packs then covered them with electrical tape. It didn't fix the problem. Bought all new packs no more problems.

 

[suprahero]

I hear about this all the time. I bought new ones and I still had the same problem. I added a few grounding straps and a HKS DLI and it went away. Now I have the Celica coils on it and they don't even know what a miss fire is.

 

[OneJSupra]

Your coils could be on its way out. My car doesn't break up boosting to 22psi with .028 gap on my plugs.

 

[1wickedA70]

im only running 10 psi. how much is it for new coil packs?

 

[S.A. supra]

80 bucks a pop

 

[suprahero]

im only running 10 psi. how much is it for new coil packs?

There's no way it should be breaking up at ten psi due to the gap. Do you have a wideband installed? It's not running lean is it?

 

[1wickedA70]

There's no way it should be breaking up at ten psi due to the gap. Do you have a wideband installed? It's not running lean is it?

its running at about 11.2 - 12.0 at wot full it boost..i knw it sounds strange but my stock twins did the same thing on 10psi and i messed around with the gap and it worked fine, my motor is wierd i have to get the spark plugs i had on when i had my stock twins. its like my 1j only likes one specific type of plug and gap lol

 

[1wickedA70]

i just bought some bkr7e plugs, im pretty sure thats the problem cuz i have on shitty plugs. all i have to do now i wait to find a new ECU, fried my second one in a yr :'( anyone selling one?

 

[suprahero]

Bkr7e's are what you should be running. Hopefully that will help once you get your ecu replaced. Good luck.

 

[A32Boost]

wats size inj. are you runnin

 

[1wickedA70]

440cc

 

[2JZ_MA70]

Get your self 300m coils... from a 3.5L or Intrepid coils. DSM's use them... they work great(and only $30each). I have them on my car... No problems at 35psi.. (with AEM TwinFire)

Didnt see the 440cc thing at first... Is that on the factory ecu or you have something to trim the fuel back....

 

[OneJArpus]

What year 300m coils?

Do they use the same clips as the 1j/2j? do they use the 1j/2j ignitor or do they have built in ignitors

 

[2JZ_MA70]

Same connector and no igniter... =) enjoy...

 

[2JZ_MA70]

Also make sure you have NGK copper plugs!!!! nothing else works as good....