Quote:
Originally Posted by blue62
When you disconnect the MAF the system defaults to open loop. There is no fuel correction (trim) happening while in open loop operation. That is why your fuel trims show close to 0%. Fuel trims mean nothing in open loop operation.
What is your MAF voltage with key on engine off??
What is your MAF voltage with engine running at idle?????
Have you disconnected your battery or had a low or dead battery in the recent past????
You say you reset the ECU... what did you do to accomplish that??? What do you mean by you reset the ECU???
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With the MAF sensor disconnected the fuel status still said closed loop using O2 sensors and short term fuel trim still varied by a few percent, it was just a lot closer to zero than with the MAF connected.
As I understand it fuel trim is set by the pre-CAT O2 sensor and if the MAF sensor is disconnected the ECU reverts to the inbuilt map for air flow. The MAF sensor fine tunes the air flow to control emissions.
I didn’t measure MAF voltage, my reader gives g/s, it was zero with the engine off and 6.5g/s at idle.
I disconnected the battery for 10 minutes to clear the ECU as recommended when replacing O2 sensors.
Regarding ECU bolts I knew they were Torx T20 security bolts and had a driver, but the security Torx we use here are 6 point and Porsche used an unusual 5 point, I have the correct TS20 5 point coming tomorrow.
Robin