I have a problem that fuel trim mid never changes, car is a evo 8 with ID1000 injectors, no rear O2 sensor. I reset the ecu and went for a long 30 min cruise, steady speed of 60 mph and maf Hz at around 150. Never did I see the fuel trim mid change. What can I do to solve this? Car is on stock 96530006 and I only added 2 byte load. Fuel trim low works fine, and is under 5%.

 

Did you disable the rear O2 the "wrong" way, where it makes the fuel trims not work anymore?

 

It is not disabled, I got these codes now: P0136 Heated Oxygen Sensor Circuit Bank 1 Sensor. P0141 Heated Oxygen Sensor Heater circuit Bank 1 sensor 2.

 

Looks like both of your O2 sensors, front and rear, are having issue that need to be fixed. Fix those first, then your trims should work.

 

Rear O2 sensor is removed, but nothing changed in the software, front O2 sensor seems to react normally it fluctuates between 0.1 and 0.9 at idle, fuel trim low is also working like it should. Car idles at 14.7-15.4.

 

Mmm, check your low-mid FT cross over point. There is a table for it.

 

Both the errorcodes relates to the second O2 sensor does these errors needs to be fixed before the fuel trim mid will work? What is the name of that table? I cannot find it in this rom.

 

it seems it is named LT trim control? I do not have it in this stock rom then.

 

add the rear 02 patch or switch to the tephra v7 rom which has is in there

 

Today I tried V5.1, by default the rear O2 sim is activated. I cleared the codes, and one code came back after a while. P0141. Shouldn't the O2 simulator solve this? Or is a resistor mod to the plug needed?

finally a other number instead of the 0% at mid fuel trim was shown, but it never moved throughout a 30 min cruise. It stayed at -9.25... %. Any suggestions?

 

I applied the heater patch, no errorcodes anymore, made a log at cruise, and no change in fuel trim mid , this is really annoying, I started another log, I saw different values for fuel trim mid, so it seems it is changing in the background but evoscan is not logging it.

 

Email me your ROM and Ill see if I can find your issue.

jay@boostedtuning.com