Volvo: code p1171, fuel air mixture, mass air flow

Question
Hi, I have a volvo 1998 2500 V70 XC (low compression turbo). The engine light came on so a friend with a garage ran the car thro his machine and it came up with code P1171, it also doesn't seem to want to rev past 4000 revs. My friend said he had reset the codes to see if made any difference and the light HAS gone off but still won't rev any higher. Can you please give me further info to pass on to him to try to mend it?? Thanks.

Answer
Roz,
Sorry but the code you have provided is a generic one and I have no listing for it. Best thing is to get to a shop that can read the manufacture codes and see what they are.
Now I do have a listing for P0171 and that is:
Condition

The Engine Control Module (ECM ) receives information from the Heated Oxygen Sensor (HO2S ) about the fuel/air mixture in the idling and partial load ranges. If the fuel/air mixture deviates from optimum the short term fuel trim will compensate for this by adjusting injection time so that optimum mixture is achieved. When the short-term fuel trim makes an adjustment, the integrator median must be adjusted by the long-term trim. When adaptation is almost at its maximum level diagnostic trouble code (DTC) EFI-232 (idling range - 0.48 ms to + 0.40 ms ) or diagnostic trouble code (DTC) EFI-231 (part load range 0.773ms to 1.227ms ) and the status message Upper limit (lean fuel/air mixture) or Lower limit (rich fuel/air mixture) will be stored.

Substitute Value

None.

Possible Source(s)

Upper limit:

Defective mass air flow (MAF) sensor
Low Fuel pressure
Air leakage
Faulty pulsation damper
Faulty sensor signals.

Lower limit:

Defective Mass Air Flow (MAF ) Sensor
High fuel pressure
Leaking injectors
Leaking Evaporative Emission (EVAP ) System
Contaminated engine oil
Oil level too high
Faulty sensor signals.

Fault symptom(s)

Can result in high fuel consumption
May result in poor performance