Volvo: C70 (1999) Idling Problem, mass air sensor, o2 sensors

Question
Hi,

I have a '99 C70 which runs great except for an idling problem. At idle the engine quickly alternates being surges and calm (1 1/2 seconds surge then 1 1/2 seconds calm). We initially thought it was the mass air sensor, and changed that, but the fluctuation continues. The same mechanic said it may now be the accelerator position sensor, but I know tend to doubt his judgement.
Have you any idea what the problem might be?
Thanks,
Ken

Answer
Hello! It sounds like you may have a problem with the ETm(electronic throttle module). There could also be a fault with the O2 sensors. There could also be a clog in the PCV system. I would have the car checked by a Volvo technician for an accurate diagnosis. If the ETM is bad, it will be covered under warranty. Even though the car is out of warranty, the ETM warranty has been extended for 10 years or 200,000 miles. You will have to have a dealer do the repairs.

Jimmy