My S80 has been hard to start since I bought it 6 months ago so I brought it into the dealer for repair. After it was done, the dealer said it had a bad speed sensor and replaced it and he also pulled a fuel pump error code, so I had them replace that as well. It was still hard to start and sometimes runs rough and stallsand eventually it would not start so I had it towed to another deal who said he got the car running by rerouting the speed sensor wire, but could not diagnose the hard starting or stalling problem because there are no error codes stored (couple of weeks after the first Service)so he could not diagnose it any furthur!!. The Mechanic said that there was good fuel pressure, good injector pulse, no fouled plugs and good compression. It also had a good ground to the bell housing but may have oil and dirt between the bell housing and engine block??. Could there be a mechanical problem not monitored by the ECM? a faulty sensor not tripping an error code? Any suggestions would be great, Thanks, Tim

Poor performance without error codes - contamination or dirt in fuel system? Vacuum leak? These things are often intermittent. Any relationship to outside temperature, humidity, engine warm or cold?

Yes, it starts up after a couple of seconds of cranking once it reaches operating temp. or(10 minutes of idling) if you shut it off and try to restart, it it could take 15 seconds of cranking or might not start at all until it cools down (after a couple of hours) if it does start back up, it runs terrible, it tries to stall out, other times the idle will surge to 1200 RPM and then drop down to 600 RPM. It has a brand new fuel pump and fuel filter, plug, Coil Packs. Thanks for the reply, Tim