Volvo: diagonostic codes and rattle/ticking under dash, fuel air mixture, mass air flow

Question
Hello, I have code p1171 showing manufacturing control/fuel air metering. I saw your answer from the 9th, but do not know how to trouble shot the problem. Light came on and went away after 400 miles. Came on again and I scanned it and cleared it. Out for the time being.

I have an annoying rattle/tick under dash. I have pulled the dash off but cannot find the offending rattle. Concrete highways to just a little bumpy road will cause it to make noise. Not sure what to do. I am unable to get foam padding in around the air ducts. I think it maybe where the dash mates up just behind the defrost vents (male/female type joint). It has felt like material on the dash. Maybe some foam (soft) under the dash in what appear to be contact points. I hate it.

Thanks
Michael

Answer
Mike,

Diagnostic Trouble Code (DTC) Information

Condition
The control module receives information from the heated oxygen sensor (HO2S) about the fuel/air mixture when idling at both the lower and upper part-load range. If the fuel/air mixture deviates from [lambda]=1, the short-term fuel trim will compensate for this by adjusting the injection time so that [lambda]=1 is achieved. When the short-term fuel trim makes an adjustment, the integrator median must be adjusted by the long-term trim. Diagnostic trouble code (DTC) ECM-261A will be stored when the long-term trim must be adjusted to almost maximum in the lower part load area.

Condition
none

Possible source

Upper limit:


intake air leakage
exhaust system air leakage
low fuel pressure
defective heated oxygen sensor (HO2S)
Lower limit:


intake air leakage
high fuel pressure
leaking injectors
defective mass air flow (MAF) sensor
contaminated engine oil
oil level too high
defective heated oxygen sensor (HO2S)

If none of the dash mounts are broken then the only choice would be to insulate and cushion.