[QUOTE=blue62;643426]
Quote:
Originally Posted by DrRobin
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[/QUOT
Whenever you disconnect your battery you need to recalibrate your E-gas throttle.
The idle and low rpm issues your are having often happen after a battery disconnect.
You could also have a faulty MAF sensor, but I cannot tell if it is faulty without voltage readings.
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I did a throttle calibrate but it made no difference. I will try to get MAF voltage readings tomorrow. Hopefully my 5 point T20 Torx will turn up and I can get the MAF out for a look and possible clean.
By the look of the screws the MAF has never been changed and I haven’t seen it on a bill for the 14 years I have had the car so it stands a good chance of been faulty, especially at 93k miles. A new Bosch MAF is £90, so not too bad if it fixes the problem.