2004 Volvo xc70 wagon AWD just over 260,000 km, 2.5 litre turbo engine. I recently replaced the fuel filter and fuel pump in the rear gas tank and that fixed the low fuel rail pressure causing starting problems. I am still having a strange problem with this cars engine when it first starts it idles fine and when put into reverse or drive it idles fine but soon as I step on the gas the engine hesitates for about 5 or 10 seconds then quickly picks up and runs fine no hesitation as long as the engine is not shut off. the car will repeat the same symptoms every time the car is shut off and restarted even after hours of highway or city driving, also replaced all 5 ignition coils and spark plugs with no change, any suggestions here? thanking the forum in advance.

 

Have you scanned for any stored codes and to capture run time fuel trim/delivery data? I'd be suspicious of a fuel pressure issue - not sure if your year has a pressure sensor or pressure regulator (somewhere in the 2004 to 2005 range Volvo moved to a variable speed pump to regulate fuel pressure and those models have a pressure sensor vs regulator.

 

A update here, recently noticed when engine is first started and pulling away in drive the stability indicator light flashes for a few seconds the same time as the engine hesitates then everything runs fine until the car is shut off and will repeat these same symptoms every time. checking fault codes with OBD- 11 scanner just had PO132 02 circuit high voltage bank1 sensor1 which I cleared, my engine fuel rail has no pressure sensor or a PEM control module to control fuel pressure, would appreciate any suggestions here.

 

Your stability control system might be preventing the engine from running properly. It is capable of reducing power and braking selected wheels to prevent the car from going out of control if it detects a problem with Throttle position, steering angle, tire slippage and yaw. I realize the car is not moving or moving very slowly. First step would be to scan the car with a scan tool that can talk to all of the control units, not just a cheap obd tool. Your O2 sensor should not be causing a running problem when first started cold. The o2 sensors have to get to xxx degrees to give a valid signal so the ECM ignores them for the first minute or so.