1JZ diagnostic guru needed

foordoorracer

New Member
Feb 23, 2009
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I have an mk3 that I am trying to finish my 1jzget swap into. The wiring has been done by someone that has done the swap mulitple times. The motor and everything is in and wired up correctly with continuity from the the ECU plugs to each sensor. Engine starts up great and sounds good. but....

PROBLEM: when the revs get to a certain(always the same right around ~2500) RPM, it cuts out and stops firing until the engine RPM slows back down below that certain RPM then is will continue to run but just wont go past that certain RPM.

troubleshooting ive already done(all testing done in neutral not under load):

-tried 3 different ECU's(one even that is guaranteed from a shop that recapped it)
-tried 3 different ignitors
-tried 2 different map sensors
-tried 2 different TPS
-tried 3 different Crank sensors(1 being brand new)
-tried 2 different sets of Cam sensor(all tested well on DVOM)
-tried 2 different Air intake temp sensors(both tested well on DVOM)
-Fuel pump keeps pressure even during problem according to AFPR guage
-tried 2 different sets of injectors(370's and 440's)
-tried 3 different sets of coil packs
-disconnected intercooler piping to test NA to make sure the turbo wasnt feeding too much air for the injectors to handle(which would supposedly cause a MAP signal justifying a fuel cut)

Modifications from stock:

-bullseye t67 single turbo setup
-2 1/2 inch intercooler piping
-440cc injectors
-aeromotive manual fuel pressure regulator(set at 32psi now)
-bosch 255lph fuel pump
-tial 65mm wastegate

IDEAS/QUESTIONS:
- When the ECU cuts fuel, does it do it by cutting the pump or injectors?
- Is there more than one reason besides MAP reading that the ECU would cut fuel?
- Can the ECU cut spark if it still has good IGF, CAS, CPS signals? WHY?
- Would me having a mk3 na Cluster(doesnt register rpms guage) have anything to do with it?
- Since the Fuel pump relay send 2 diff voltage referenced to pump(~6v idle-light load and 12v for heavy load) does the ECU see a signal from this that would cut injectors if it wasnt getting a reference signal from the "heavy load" once the relay switchs?
-SUGGESTIONS???
 

Jostar

AEM powered 1JZGTE!!!
May 21, 2007
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Check the Ignition coil clips, See if on of the cables or clips are broken, I had that issue on a buddies car..
 

mkiiichip

New Member
Sep 10, 2007
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foordoorracer;1698025 said:
-Fuel pump keeps pressure even during problem according to AFPR guage

:aigo: You are joking, right?

foordoorracer;1698025 said:
- When the ECU cuts fuel, does it do it by cutting the pump or injectors?

Injectors

foordoorracer;1698025 said:
- Is there more than one reason besides MAP reading that the ECU would cut fuel?

Yes, for instance when the idle is uncontrollable.
It usually happens when the ECU has lost control.

foordoorracer;1698025 said:
- Would me having a mk3 na Cluster(doesnt register rpms guage) have anything to do with it?

No

foordoorracer;1698025 said:
- Since the Fuel pump relay send 2 diff voltage referenced to pump(~6v idle-light load and 12v for heavy load) does the ECU see a signal from this that would cut injectors if it wasnt getting a reference signal from the "heavy load" once the relay switchs?
-SUGGESTIONS???

Your 1j ECU is not able to control this function, it should be eliminated. You want 12v at the pump at all times.