In the shop I have a fully built 2JZGTE VVTI setup in a MK4 Supra that is running in a MS PnP Pro box. It's the updated hardware that addresses the cam sensor circuit that had a lot of trouble in the earlier versions. The engine harness is a brand new OEM unit that was installed at the same time as the motor & ECU. Running the 1.5.1. release firmware and the 2JZ VVTI wheel decoder. VVTi works perfectly as commanded in the tune. Ignition is IGN1A coils. I've done several very similar builds to this one making well over 1000whp using the MS PnP Pro and have not run into this issue before.
Car runs as expected, all the way up to 8800rpm at any power level below 850-900whp. If I try to make any more power than that it hits a very nasty cut as it loses sync around 6500-6800. The SYNC LOSS REASON = 84 when this happens and is very repeatable on the dyno. James (or anybody else who many know), what does reason 84 mean when running the 2jz vvti wheel decoder? as I could not find anything on it in the current manual.
I'm wondering if it is somehow related to the ignition system as it only happens at high cylinder pressures, but these ign1a coils are not even breaking a sweat yet. It is NOT blowing out the spark as that would behave very differently, intermittent, gets worse with more boost, etc. This is a VERY abrupt cut and you see the RPM signal drop away for a split second...hence the Sync Loss Reason 84.
I'm pretty sure the ignition system itself can be ruled out as I put the exact same coils/wires on another 2J I had in the shop and ripped off a 1400whp pass with the same dwell configuration. They also are properly wired with their own custom subharness that I did myself (2 40amp relays, grounded to the head, run separately from the primary harness, etc.) which is the same way we do it for all ign1a 2J setups.
2JZGTE VVTI Sync Loss (reason 84) at High Boost
Moderators: jsmcortina, muythaibxr
Re: 2JZGTE VVTI Sync Loss (reason 84) at High Boost
If I read the source code correctly, reason 84 is specific to the 2JZ wheel decoder. It is set if the missing tooth section of the 36-2 wheel is shorter than 1.5 normal teeth - it should be ~3 normal teeth long. The code counts teeth, starting from 0, and checks on the 34th tooth edge, which should be the end of the missing tooth section.
For the reason 84 to get set, I'd guess that noise (or vibration?) caused an extra tooth edge. A composite logger log of a lost sync event would help diagnose this. Do you have any noise filtering enabled? If so, I'd try turning it off and see if the sync loss occurs at lower RPM/Load (and get a composite log of this).
For the reason 84 to get set, I'd guess that noise (or vibration?) caused an extra tooth edge. A composite logger log of a lost sync event would help diagnose this. Do you have any noise filtering enabled? If so, I'd try turning it off and see if the sync loss occurs at lower RPM/Load (and get a composite log of this).