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Just wondering if anyone else had a similar issue. My ms3x have been tuned by a reputable tuner for a few years and this just started happening earlier in the season. I figure I'd try to fix it before letting my tuner take a look.
Everytime when I'm accelerating and building boost, as soon as I snap the throttle closed, my RPM gauge sweeps widly trying to stabilize and I'm getting no power. Its almost as if its misfiring and struggling to stabilize engine rpms. Sometimes my rpm would not stabiize and I'll stall out inbetween shifts and I have to kick the clutch to get it going. The other few times its struggling to fire and eventually it'll stabilize with some opening of the throttle. I could run it in 5th and build 15psi all the way to redline no problems, but like I said, as soon as I lift off I'm having issues.
I've been able to reproduce this problem and it seems to only happen during moderate to heavy acceleration under boost. If i'm grannying it and staying out of boost it won't happen at all.
At first, I thought maybe it could be my stock coils going but this happens only when I close the throttle under boost conditions.
Another theory I might have is maybe I'm getting too much fuel as soon as I snap the throttle closed under heavy demand, the ratios could be off and I'm not getting a consistent firing during the transition from boost to vacuum conditions. Halp?
Mods - Tuned MS3X 2001 Miata Forged 1.8/EFR 6758/FF640/DW200. I have attached a log/tune in case anyone wants to take a look.
Just briefly looking at your log, it seems like the ECU is losing sync. I can't look at your datalog from here nor do I know if it logs sync errors, but first I'd make sure that's not the case before worrying about fueling and stuff. The ECU should still have an accurate read on engine RPMs regardless of fueling and timing. With my BP4W the cam sensor was failing and would cause the ECU to stop reporting RPMs briefly and then come back on. Eventually, it worsened to me getting stuck on the side of the road. I know the VVT engine doesn't have a cam sensor like the BP4W but I'd look into whatever it does have if you do confirm that it is losing sync.
Just briefly looking at your log, it seems like the ECU is losing sync. I can't look at your datalog from here nor do I know if it logs sync errors, but first I'd make sure that's not the case before worrying about fueling and stuff. The ECU should still have an accurate read on engine RPMs regardless of fueling and timing. With my BP4W the cam sensor was failing and would cause the ECU to stop reporting RPMs briefly and then come back on. Eventually, it worsened to me getting stuck on the side of the road. I know the VVT engine doesn't have a cam sensor like the BP4W but I'd look into whatever it does have if you do confirm that it is losing sync.
Thaks for your reply. I dug a bit further and it just looks like it goes super rich when I let off. I turned off over run and it hasn't happened since. Right when I snap the throttle it goes super rich. I'm assuming when I reapply the throttle quickly right after there is some fueling I have to correct.
08-16-2023, 01:30 AM
Firing issues inbetween shifts
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