I have had my poor XC go through some trauma recently, of most impact was the ETM being fitted with the gasket bent over in one corner which was causing some serious idling and running issues. It was getting P2097 (too rich) codes, and once I fixed the gasket I started getting P0171 (too lean) codes, which made sense in a way? Stopped the vacuum leak and the mixture codes crossed over? So I thought things will even out? I even did what I thought should reset the fuel trim, disconnecting the battery for half an hour and pushing the brake pedal to deplete any residual volts in the system. Sadly things haven't improved, the idle is rough and I'm getting P0171 code with the long term fuel trim at 23%. Something still ain't right. I can't find a vacuum leak, the MAF sensor is less than 12mths old, fuel pump is not very old, and since the codes have crossed from too rich to too lean I can't see the fuel pressure being the root issue? The PCV is all clear and there is no sign of crankcase pressurisation from the dipstick after a good drive. Can't see or smell any fuel leaks around the injectors when cold, and once again the changing of the fault codes when the gasket was fixed suggests the injectors probably are not the constant fault? Could it be the pre-cat O2 sensor? It looks to be the original and the car is quite senior in mileage. I replaced the rear one as part of my ass chasing before finding and fixing the folded ETM gasket. My theory is that the pre-cat sensor is setting incorrect mixture, and the post-cat is detecting the error? I declare myself a Volvo student and hope for some good advice.
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Jorgan - Aussie -