Diagnosing a stutter....

[Joe H]

The previous owner had misfiring problems that I have been working through and the car is now generally working well except that it still has a stutter / misfire, especially at 1500-2000rpm. Above that it is very smooth. On a trailing throttle within that range it is very jerky. Sometimes it does the same at lower rpm, with low power moving from rest.
No fault codes normally showing.

Yesterday after 100miles it became much worse and showed ECM-135F MAF signal too high. Not sure if that is pointing to a faulty MAF or something else.

Do these readings it stored give any clues? eg, it seemed to happen at almost full engine load. The inlet temp seems too high as well.
Any pointers how I fault find?
It has had a new Swirl mechanism, also fuel and air filter, EGR cleaned out and working, no obvious leaks in the induction pipes.
Cheers
Joe

[Joe H]

Any pointers, anyone?
Cheers
Joe

[The Thong]

What car, year and engine?

TT

[Clan]

Originally Posted by Joe H

The previous owner had misfiring problems that I have been working through and the car is now generally working well except that it still has a stutter / misfire, especially at 1500-2000rpm. Above that it is very smooth. On a trailing throttle within that range it is very jerky. Sometimes it does the same at lower rpm, with low power moving from rest.
No fault codes normally showing.

Yesterday after 100miles it became much worse and showed ECM-135F MAF signal too high. Not sure if that is pointing to a faulty MAF or something else.

Do these readings it stored give any clues? eg, it seemed to happen at almost full engine load. The inlet temp seems too high as well.
Any pointers how I fault find?
It has had a new Swirl mechanism, also fuel and air filter, EGR cleaned out and working, no obvious leaks in the induction pipes.
Cheers
Joe

atmosperic pressure seems low ? compare it to the other pressure sensor ( Boost pressure ) with the engine off , they should both be very similar . Boost pressure sensors seem to be playing up lately ...

[Joe H]

Originally Posted by The Thong

What car, year and engine?

TT

Sorry, I was sure I put that in the post...

XC70 D5 185 2006 (facelift) with DPF and auto.

Joe

[Joe H]

Originally Posted by Clan

atmosperic pressure seems low ? compare it to the other pressure sensor ( Boost pressure ) with the engine off , they should both be very similar . Boost pressure sensors seem to be playing up lately ...

Good catch, Clan. Can you point me to the location of the boost and atmospheric sensors? My Vida is some distance away currently.

Thanks
Joe