Biggiesacks

The ecu uses the o2 sensor and closed loop to determine the correct fuel trims. Once the trims have been learned they are then applied against the final calculations in closed and open loop. This is why you need to get your fuel trims +-3% on tuning otherwise it will throw your whole fuel table out of whack.

dsmchiz

Some great info in this thread. Hopefully Christian and I can get this figured out next month and hopefully this thread will help others later understand this code

Thank you all!

LetsGetThisDone

iTrader: (1)

Fuel trims are not active in open loop.

Biggiesacks

I could be wrong, I was always under the impression that LTFT's had an effect on global fueling. Ill dig around and see.

Biggiesacks

this is actually strangely hard to sort out through basic searching. The evo x for sure had ltft effecting wot, and there are guides on how to disable that etc... For the 8/9 it is a little harder to find. There where threads that seemed to ended without a consensus. Probably one of the more recent things i have found on it was this :https://www.evolutionm.net/forums/ec...m-control.html which seems to say that ltft's do effect open loop fueling and describes the different maf hertz that the ecu switches between different ltft's at. I have to take a break from this for a bit but if anyone else can point out some informative threads etc on this I would really appreciate it.

LetsGetThisDone

iTrader: (1)

If the ECU is doing that, it's hidden. When the car is truly in open loop (cold start or WOT, or forced into it with ROM changes), the "fuel trim is use" column is always blank on data logs.

Biggiesacks

Ok found where i got it from: Pg 35 of http://www.evoscan.com/ecuflash/Merl...UIDE-V1.7a.pdf states "
Note that when the ECU is in OPEN LOOP, the LONG TERM FUEL TRIM (LTFT) % that was applied in CLOSED LOOP is applied to the whole map. This is a great feature, but does mean you should try and get your trims close to zero by getting the scaling and injector set correctly."

Now Im not claiming this information is correct, its just what I have gone off of, and if in fact it is wrong then that would be great to know.

LetsGetThisDone

iTrader: (1)

I highly doubt Merlin is wrong and I'm right. I'm just going off of EvoScan doesn't show "fuel trim in use" when the car is in open loop. Merlin has actually gone through the ECU and decoded everything and can actually see all of the strategy.

Biggiesacks

I didn't want to assume to know where you where getting your data from, and I couldn't remember where mine came from either. Maybe something new had come to light? Anyway Im glad we got it straight.