MX5RACER

I am helping a friend make some changes to his racecar. We recently updated to the Skunk2 throttle body and injector dynamic 1050 injectors in prep. for going E85. After turning on Flex Fuel, updating the dead times for the injectors (Per Injector Dynamics spread sheet) and updating the required fuel, we are now getting a misfire or bucking condition between 3800 and 4400rpms just as the car comes on boost. The AFR's all seem to make sense and are close to our targets. With VE Analyze Live running, it is not making large changes so I think we are in the correct ballpark for fueling. Could there be an issue with the deadtime settings causing an issue with fueling as it comes into boost? Pushing past the misfire window and the car runs fine. Any guesses?

MX5RACER

Car owner also posted, but in another section. He posted data logs and msq.

2 Weeks of Injector Hell - Miata Turbo Forum - Boost cars, acquire cats.

Ted75zcar

iTrader: (2)

The fueling posted in that other thread is wack. I would start there.

MX5RACER

The fuel table was just starting be refined, but we were hesitant to push through the misfire around 4k. The other puzzling thing for us was how small of a difference there was from the VE numbers at idle compared to full boost.

Ted75zcar

iTrader: (2)

Use easy and interpolate in the area of concern for a few pulls to quickly bring numbers to a reasonable value. Sneak up on it, as misfire will corrupt the WB reading. The first thing you need to do is get the AE to not be triggering at wide throttle angles. Autotune won't correct when there is an AE event.

usually an indicator of the wrong deadtime or SSPW

MX5RACER

Thanks, we verified the dead times with injector dynamics as soon as we were having issues. Also, talking with DIYAutotune, they mentioned the TPSDot curve being off. I mentioned to them that it was straight from their basemap for the MS3ProPNP ('99-'00) and they did not have an answer. I was thinking to use something less aggressive like the one on the Mazdaspeed version. Is there a curve you would recommend trying for AE?

Ted75zcar

iTrader: (2)

AE is a tuned parameter, not one that can be leveraged. I recommend either disabling it or reducing it to only off-idle transients until the VE table is more appropriate.

You need to use SSPW with injectors that large. The effective PW at idle is measured in microseconds.

Edit: I have to think somebody has created a how to video for AE on YouTube or something