Guys I have a mate with a Zafira 1.816v year 2000. He has had a recent problem develop that 3 local garages have not been able to idenitfy and have made him replace various parts with no benefit.
The car is missing slightly on idle and low revs (up to about 2k) then it clears. You can hear the misfire from the exhaust and from the engine but only just. It is also got a very slight tapping/squeaking noise from the engine bay. To the ear it doesnt sound like from the block/head itself but more like external.
The car is juddering slightly and lack of power - all the indications of a misfire. He says when on the motorway at around 70mph the lack of power goes and the car runs smooth as it always has done.
The EML is on and the follwoing codes are in the system
P0325 - Knock sensor
P0136 - 2nd Lambda sensor
P0301 - Misfire Cyl 1
P0170 - O2 sensor exhaust
P0100 - MAF sensor
P0110 - Intake air temp
He has replaced the plugs, coil pack and AFM all with genuine parts and had all the codes reset. They come back on within 2 miles of driving the car. One garage has checked the lambda probes and said the resistance is within spec.
I am stumped! It is all pointing towards a misfire as the intital fault causing the rest of the codes to come on? But with new plugs, coil pack and AFM I cant suggest anything else, Perhaps knock sensor? The AFM was replaced about a year ago. The plugs and coilpack 2days ago.
If I reset all the codes and disconnected the AFM then start the car obviously it will bring up a code for the AFM but is that a way of diagnosing the AFM as possible failure or will it just run crap because it is not connected. I know on my Z20LET if I disconnect it it will bring the EML on but will idle smoothly.