MazdaSpeedDan

iTrader: (4)

Car runs in limp mode with 2 known good ECU's.
Car runs in limp mode with PFC tuned for pretty much stock motor.
Car runs fine with PFC tuned for a 500hp motor with bigger injectors and other work done to it.


Car has 3' downpipe and no other mods.

Car hits fuel cut at 4k rpm except when it was tested with that PFC.
Fuel system is fine, Fuel pump checked out fine. Maybe bad secondary Injectors?

Anyone help me figure out what this means?

Andre The Giant

iTrader: (21)

What codes are being thrown on the stock ecus to put it into limp mode?

zeroG

iTrader: (28)

There is no limp mode with a PFC

How many times have you swapped in and out the good and bad ecu to make sure it's something ecu related and not a random occurrence of something else?

MazdaSpeedDan

iTrader: (4)

The only code is a 05 knock sensor code, which I dont think actually throws it into limp mode though.

Its been changed out a few times to diagnose the problem, only time it ran fine was with the tuned up PFC. Wondering why one PFC works and the other one does not..

FD3S2005

iTrader: (11)

i had a similar issue which happen to be one of the secondarys, it wouldn't let me go over 3 or 4k just fell flat, put the old ecu back in and checked the codes and i forgot the code for it but, ended up changing one of the secondarys and it was fixed

MazdaSpeedDan

iTrader: (4)

Ding ding ding, Injectors was the problem.