Year of Manufacture *: 2005
Engine Size and Code *: 2.0
( Optional) Fault Codes: 3FF0, 4298.
First scan OK
second scan fault present.
3FF0 Air mass meter
4298 Lambda sond, bank 1
Vehicle was presented to me after it had been to a BMW specialist, with my level of diagnostic equipment I didn’t really want to take it on but as a favour to this long standing customer I said I’d take a look.
The vehicle has a huge lack of power until it reaches around 3000 rpm and then takes off like a scalded cat! It has been previously fitted with new injectors, inlet manifold and air mass meter all OEM parts. I scoped the priming pump (OK), injector signal (OK) I.M.V. and pressure regulator but when I scoped the fuel pressure sensor it doesn’t develop it’s pressure in a linear fashion when accelerating, the pressure remains low until the revs get to 3000 and then the pressure goes up to what I would consider normal. During this period there is a missy feeling to the engine, I wasn’t sure this was a symptom or an actual fault so I scoped the manifold pressure sensor and sure enough the turbo had the same non linear build up of boost. I bit the bullet and removed the turbo but found nothing wrong with it the variable vanes were all perfectly free and very little in the way of carbon deposits. The strange thing was after refitting the turbo the car returned to normal so I re tested the fuel pressure and sure enough pressure development was back to normal! After about 5 mins the fault re-established itself, I talked to the previous garage about the fault and they said that after fitting the AMM they had the same thing the car recovered it’s performance for a short period of time. I’m now at the point of having the ECM tested if possible, any ideas would be really helpful?
Sorry for the long post.