Greetings All,

My '02 s60 has been in the Dealership for three days now. Car was showing "Reduced Engine Performance" message under load [me driving without kids in car] and occasional drawn-out starts. Otherwise ran OK. Car has 140,000mi on it - have owned since new & it has been well maintained.

Car needed a new MAF - I replaced. CEL came on -- Autozone reset it - code was "low fuel at startup".

Has shown code 5022 for RPM sensor for awhile, but intermittent. Dealer Tech replaced sensor, which was covered with fuzz [shavings] and had a bit of a dent in the end. Code went to permanent.

Tested the wire harness since its getting a weak signal from the RPM sensor. They called Volvo-and got some tips :

They cleaned corrosion from a few pins under the ECU. They tore through the harness 3 or 4 times. Their suggestion is to pull the trans to check the flywheel and the electrical connection between the engine and the trans.They say it might be the flywheel teeth. That's a HUGE labor bill considering that the car still runs.

My thought is, why not put a capacitor or some electrical doo-dad in line to even out the signal??

Anyone an EE? I went to Lehigh, but I studied business.

I'll get the electrical signal specs and post them after I pick the car up tonight.


Thanks for any help that is offered,
Brian

Based on what you say your dealer techs have little understanding about auto electronics in general.

The various sensors including RPM sensors and their associated circuitry are designed to be somewhat tolerant of faults such as interference by external electrical noise sources, corroded grounds, etc. There would be little or no sense in trying to clean up or condition sensor signals - they are rather closely specified.

I guess the RPM sensor is supposed to pick up the flywheel teeth - and if a couple of teeth are missing I think there would be a consistent misfire code (acting like rpm is uneven during each and every rotation of the crankshaft, as happens when one cylinder is not firing). You should get a persistent code for this just as you would for a bad spark plug wire or fuel injector. They or you could pull the starter and inspect the teeth, maybe. Missing teeth usually mean the starter will overrun (not engage) once in a while if the engine happens to stop with the gap at the starter.

The electrical connection between engine and gearbox is just a solid ground - how would this fail?

I wonder what the exact symptoms are that you have right now? How is fuel usage and engine performance? Do all of the electrical accessories in the car work properly? I am thinking that there may be a fault in primary wiring or voltage regulation that is showing up as if something more subtle.

If you are not working on the car yourself, maybe it's best to contact Volvo directly and/or try independently with a different dealer.