NAXJA Forum User
Join Date: Aug 2015
Re: Long Term Fuel Trim at 92. Renix
Just gonna add a little input as I was quickly browsing the thread. Renix ECUs do have a KAM Keep Alive Memory which does store a few values such as previous LTFT, TPS closed %, and how many key cycles since a sensor fault, though I'm still trying to find that last one. The big debate is if Renix stores trouble codes which it does not save for the key cycle.
I'm going to do a lot more looking into the few mystery values still left in the stream to see what I can find eventually.
As for LTFT in general, after a reset it will read 128 which means it is using the stock look-up table. Once the vehicle sucesfully stays in closed loop then it will start adjusting STFT and an average deviation will be found which is the LTFT.
So LTFT shows you the average correction factor from the stock tables that is needed to stay stoic. STFT is the current needed deviation I think, and I forget if that changes in open loop.
Lower LTFT readings means it is using less fuel to stay stoic, and higher readings show more fuel is required. For my stroker it sits are 176 but will go a little lower if only city driving.
This is the guy who's manufacturing the in-cab diagnostic readers, he a lot smarter than me. But he knows the insides of the Renix computer and a lot of its construction.