Hi all!

Been trolling/searching the forums here and I'm worried that the Volvo I just bought is going to need some costly repairs.

Yesterday, we were stopped at a light, and the motor idle speed started oscillating. As it began oscillating, black smoke and a very pungent odor from the smoke started leaving the exhaust. This only happens when the motor is warmed up. The motor continues to run, and seems to run out cleanly, but still spewing the smoky/smelly exhaust.

One thing I need to check is if it's the MAF, so next time this behavior occurs, I'll unplug the sensor and see if the idle straightens out. However, I'm most concerned that the problem is a leaky turbo. I've noticed that I have black residue on my shop floor and what looks like light-weight, wispy carbon particles all over the floor where the rear of the car was. Also, the gas mileage seems to be less than it should be.

Any thoughts?

I'm really glad for all of the information on this forum. Some of the symptoms I'm experiencing are from the faulty ETM system that many of the folks on this forum cite as the source of their problems. I found the recall listing on the NHTSA website for the throttle control and called my local Volvo dealer with the recall number. Have an appointment scheduled for tomorrow, so hopefully that fixes my problem.

If that doesn't do it, then I'm going to go the route of cleaning the MAF sensor and throttle body.

Still worried about my turbo, however. Does anyone have any thoughts on that?

UPDATE: Just got done at the Volvo dealership. The mech on duty there said that the ETM software update for that VIN had already been done, as had the other recalls. However, he found that the ETM gasket (wherever that is) is leaking, and it happens to be covered under Volvo's extended 200,000 mile/10yr warranty. That's good, because he said it would cost almost $800.00 for them to do it if I had to pay for it.

He also said that the diagnosis revealed that both O2 sensors need replaced, and that an exhaust gasket is leaking and needs to be replaced. My question is: would the leaking ETM gasket and the bad O2 sensors be the source of my rough, hunting idle and occasional black smoke. BTW, the car hasn't done it again in the last few days.

Also, would a computer diagnosis reveal a leaky ETM gasket? My thinking is that if there is some sensor that could somehow detect such a leak, that perhaps it could cause the car to run in such a way as I have previously described. Any thoughts?