02 V70 XC 2.5T Rough start warm Tach jumps >3K rpm

NotoriousRIZ · Post by **NotoriousRIZ** » 12 Oct 2020, 10:57

I have a 2002 V70 XC 2.5T that has 115000 miles on it. I purchased the car 2 months ago from a Volvo mechanic. It starts as it should when cold or sitting after driving - usually, More frequently though starting when warm has been rough - turning over, sometime not starting, the tach jumps to >3K rpm. I don't see any of this when the car starts well - turn the key, cranks over, starts , no jumping tach, idles well around 800 rpm.

I took the car back tot he mechanic and he said - "old cars start rough". Guess I wont be using him for repairs

I've done a little research and I've seen 2 major themes: bad fuel pump and oil pan rings and seals. Looking for a little feedback if anyone else has experienced this.

Thanks!!!

motormikeyman · Post by **motormikeyman** » 14 Oct 2020, 13:11

You may have a problem with your CEM with water damage (sunroof leaks down A-pillar), CEM overheating, or it could just be the CEM connector needs to be cleaned. The CEM can do strange things when it gets warm/hot. This item can cause issues with starting (cranks but won't fire up) and also erratic gauges, warning lights, transmission goes into limp home mode. There would be communication error codes stored. There are multiple threads on this subject. Are any other lights on/issues occurring when this happens? Xemodex.com has good diagnostics for this.

NotoriousRIZ · Post by **NotoriousRIZ** » 15 Oct 2020, 06:55

I did have an occurrence of a Transmission Service Required message and the car went into limp mode - no codes when hooked up by a mechanic.
I don’t get any other lights or messages and no codes.
I will check the CEM connections