Hello folks,

I'm having somewhat of an issue with my transmission. At highway speeds (60mph+) particularly when going downhill or on level road my torque converter locks up (rpm about 2,500 at 65mph), then rpms jump up a bit (2,800 or so) then go back down, and so on. Feels like a bit of a lurch each time, not really terribly pronounced. (So many rubber parts in the drivetrain you can't really feel it.) Doesn't do it a lot and seems fine for the most part when going uphill. Driving around town is also no problem.

Checked the FAQ which gave me two leads to check the TPS and to clean the three electrical connectors on the front driver side of the transmission.

Any other ideas as to how to diagnose the problem, if it goes beyond the simple fixes mentioned above? I have a AW30-40 manual on my shelf which I'm somewhat afraid to delve into (and it refers to using Volvo special scanner for most diagnostics anyway). Any easier to obtain scanners I could use? There are no trouble codes on the car.

Besides other clearly unrelated issues one I could imagine have something to do with the problem is a possible vacuum leak at an undetermined location that prevents my AC system from working (no air from the vents, blower motor works fine).

The car had been sitting for a while while some work was being done on the engine a little bit at a time, so I guess, little electrical issues due to exposure to elements and hot weather are not entirely unexpected. The car has a recent (1 month, 1,200 miles) replaced head gasket, some head work, and the intake has been cleaned on assembly. Just fixed some EVAP related issues due to multiple rubber connecting pieces having cracked, so that sort of thing is also ongoing.

Thanks!

1998 V90 160,320 miles B6304S2 engine AW30-40LE transmission