Don -

Great info on the o2 Sensor. I think my old Radio Shack will work, it's analog and has a lot of scales.

The ambient temp sensor is what the thing is named in the Green book page on LH-Jetronic. It's the sensor, under #3 rail intake manifold, that tells the ECU when the engine temp is low, and also helps Volvo save money by not having a cold-start injector on this model. If it's kaput, I think the engine can get the cold start fuel mixture all the time.

Volvo nomenclature is not standardized. In the back of the WD Manual, the sensor is called the temperature sender. Confusing.

The air box T-stat is new. I lost only one AMM to that little jewel, and it was B4 I knew about the BrickBoard (BB) and cost me a pile instead of the $32.50 or so for the T-stat. That AMM was $450 back then.

Your Q about the temp sensor made me think about the 1988 wifemobile. When I got it, the temp gauge when warmed up read about 8:00 O'clock, too cool. I checked the thermostat, found none, and put a 92C one in. Gauge now reads 9:00 O'clock, and gas mileage went up by 2 mpg.

That brown wagon temp gauge read 7:30 O'clock all the time we were talking, so it no doubt has no thermostat and that, among other things, can explain the rich mixture.

Testing o2 sensor, do you use carb cleaner to richen the mixture? It would be easy to spray into the smaller (or larger?) PCV hose.

Thanks again for the info. I am pleased that you used the BB, as that gives the other Brickheads a chance to learn more.

Regards,

Bob

:>)