Hello, I am looking for some help with my 1996 P38 4.6 if possible. It has been suffering from a lack of power since I acquired the car, with poor fuel consumption also. I have an OBDII tester which identified fault codes PO102 and PO103 - indicating the airflow circuit both high and low at some point ? The live data monitor on the tester indicated a very low mass airflow reading of around 0.06 grams per second at idle and this rose to about 0.11 at 2500rpm. This was way off the spec which I believe is 20kg/hour at idle and rising to 60kg/hour.
I changed out the MAF after cleaning the original made only a very slight difference. However, the new MAF gives a reading of the same order.
I checked the wiring loom having disconnected it at both ECU and MAF, and continuity and isolation are good. Supply voltage to the sensor checked out also. I tapped into the signal wire at both ends and measured output voltage with a DVM expecting to see a low voltage in line with the count i was seeing on the OBD reader. However, the sensor output right at the ECU plug seems to be good. I am reading about 0.4VDC with the ignition on, about 1.45VDC on idle, and output rises gradually to about 2.5VDC at 3500rpm. This seems reasonable, although i haven't been able to find a detailed spec for the AM20 sensor. I am assuming full scale output will be around 5V but hoping somebody can confirm that.
I was thinking initially that my OBD reader might not be compliant in some way, but its reading the codes ok and the other live data like engine revs and temperatures are all sensible numbers, so have no reason to doubt it.
Has anybody seen similar to this ? I have searched at length but couldn't find anything directly related. Are there any ECU settings that could affect the MAF count ? Are there any known problems with the ECU signal processing ? Plug and socket connections into the ECU are ok, no corrosion or loose pins etc, but i haven't opened the ECU itself, in case i am making any obvious mistakes here !
I changed out the MAF after cleaning the original made only a very slight difference. However, the new MAF gives a reading of the same order.
I checked the wiring loom having disconnected it at both ECU and MAF, and continuity and isolation are good. Supply voltage to the sensor checked out also. I tapped into the signal wire at both ends and measured output voltage with a DVM expecting to see a low voltage in line with the count i was seeing on the OBD reader. However, the sensor output right at the ECU plug seems to be good. I am reading about 0.4VDC with the ignition on, about 1.45VDC on idle, and output rises gradually to about 2.5VDC at 3500rpm. This seems reasonable, although i haven't been able to find a detailed spec for the AM20 sensor. I am assuming full scale output will be around 5V but hoping somebody can confirm that.
I was thinking initially that my OBD reader might not be compliant in some way, but its reading the codes ok and the other live data like engine revs and temperatures are all sensible numbers, so have no reason to doubt it.
Has anybody seen similar to this ? I have searched at length but couldn't find anything directly related. Are there any ECU settings that could affect the MAF count ? Are there any known problems with the ECU signal processing ? Plug and socket connections into the ECU are ok, no corrosion or loose pins etc, but i haven't opened the ECU itself, in case i am making any obvious mistakes here !
