2jz popping/misfire/backfire at rpm 3k++

[nissansupra]

Hi all, i just completed mount the 2jz-gte engine in order to replace broken 1jz engine for my car. This problem happen makes me cannot feel the full potential of 2jz-gte engine (stock twin turbo). I put my process in order to make a troubleshooting/idea to this problem easier.
1. turn the key on, check engine light as normal
2. engine crank and start without showing a major problem. start at 1.2k rpm and drop to 650++ rpm (cold engine).
3. when the engine is ready (warming up about 4-5 minutes) all parts not showing any potential problem.
4. start revving slowly from idling rpm to 2.5k rpm the engine still well. everything good as expected.
5. when try to pull a little bit hard revving up to 3000-3500k rpm the exhaust give a laud backfire/firework sound with a black smoke. (smell like unburned fuel).

some try and error method to detect a problem
1. when revving the engine without intercooler, the engine can rev to 4k and higher.
2. with IC increase fuel pressure from 30psi(2bar) to 58psi(4bar) still make that sound.
3. change the spark plug still no success
4. check the vacuum hose leak
5. get the voltage reading at fuel pump (10v) even try with 12v mod (direct to batt) still no success.

Hope you may help me to solve this problem. Thank you in advance.

 

[Nghty89]

Have you checked the timing? Have you checked for any possible boost leaks within the intercooler itself? Any idea what your air/fuel ratios are? Have you checked for any codes from the ECU? Does the ECU light come on when you backfire at that rpm? Does it go away after the backfire? Can you drive normally without getting into boost?

 

[nissansupra]

Have you checked the timing? Have you checked for any possible boost leaks within the intercooler itself? Any idea what your air/fuel ratios are? Have you checked for any codes from the ECU? Does the ECU light come on when you backfire at that rpm? Does it go away after the backfire? Can you drive normally without getting into boost?

timing is fine, no boost leak, intercooler also fine (when no intercooler connected no backfire/misfire happen)
no idea on A/F ratio since i not having any gauges/tools to measure it.
ecu not throwing any code. ECU light not come out when backfire
it keep backfire when revving it (with black smoke - unburned fuel)
i can drive normally without boost

*i suspected the wiring issue make me facing this problem since i read a thread at one of the xjz related board. the problem almost same like me. he solved it by rewired the NSW. but then i dunno how to trace it any guide?

 

[gurley0916]

Look at this thread if you have a DM Fuel dampener bypass line http://www.supramania.com/forums/showthread.php?127857-Unique-1jz-3k-rpm-breakup

 

[nissansupra]

Look at this thread if you have a DM Fuel dampener bypass line http://www.supramania.com/forums/showthread.php?127857-Unique-1jz-3k-rpm-breakup

thanks, for the links. i will check mine.. i will update if success

 

[Nghty89]

Sounds pretty plausible, but without a list of mods we wont know.

EDIT: He responded before I did. lol


Good luck figuring it out! Hopefully it's that simple.

 

[nissansupra]

Sounds pretty plausible, but without a list of mods we wont know.

EDIT: He responded before I did. lol


Good luck figuring it out! Hopefully it's that simple.

normal swap.. no modification so far, except im using GTR intercooler.. others are same like what we saw on the front clip.

 

[nissansupra]

still no luck.. arhhh

 

[nissansupra]

today checking up:
1) check coil on plug condition using multimeter.. still in good condition
2) check NSW wiring... NSW(#76) supplied with constant 12v (IGN)
3) using stock FPD with 1jz fuel pump

status.. still popping and misfired

 

[k20maniac]

are you running a map sensor?, sounds like the issue is when your hitting positive pressure in your intake manifold.. are your plugs gapped correctly?