I'm tuning a track only Mazda MX5 with a LFX/6spd manual swap that is a bit of a mess. The engine and harness are supposedly from a 2014 Camaro, the ecu is from a 2012 camaro and the intake and exhaust are custom, no cats and everything internal is stock. It starts instantly every time but runs extremely lean when cold for the first 10-12 seconds and will die if you don't feather the pedal to keep it running. After those 10-12 seconds it smooths out and runs well. It won't get over 55% throttle but shows 99.6% for pedal position and it won't rev past 5300rpm. It will close the throttle down to 33% to hold at 5300rpm. It shows axle torque is closing the throttle but I can't find any torque tables that haven't been maxed out.
I also have an ecu from a 2013 Camaro, which is the e39a instead of the current e39 that is in it now. I can try swapping to the spare ecu and purchasing credits for that but I'd like to get a handle on what is causing this before throwing more money at a guess. Any help is appreciated.
I've attached a free rev log, a log of a short drive and the current tune.
Hey there 376FD. I built a 90 Miata with an LFX and fought through several issues similar to yours. I will tell you right off the bat that there is almost ZERO support for the e39 ECU out there but I have been able to figure a few things out and I'm sure that if we work together we can sort out the other things too.
Do you happen to have a Vitesse throttle controller installed? If so that may be the cause for the odd TPS readings.
I was able to fix a similar RPM issue but until I know for sure what variable fixed it I will hold off on documenting the "fix". I will PM you my cell number and we can talk through a few things live.
Are you getting a CEL and if so what codes is the ECU throwing?
I'm actually trying to keep it as stock as possible to eliminate issues like that that. It's a factory pedal and seems to read properly, it gets to 99.6% which is close enough for me. No CEL, the only code it's currently throwing is for lack of a CEL circuit. Go figure. I will add a CEL to it in the future so I'm letting that lie for the time being.
I did another LFX swap into a RX8 and it didn't give me nearly this kind of head ache, which is why I'm wondering about different ecus.
Got back from the track and got to do some more playing with it, got the VSS working but it only works on the e39 ecu, not the e39a. Both ecus will give me full rpm but not full throttle. The two exhibit slightly different tendencies but overall have the same results in power and allowed throttle. If anyone has an idea on what I'm missing to get full throttle I would love to hear it.
Last edited by 376FD; 09-21-2017 at 04:36 PM.
Reason: added log and tune
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