Would anybody mind explaining the trans mod valve?

 

I have heard that if your car smokes really bad but it doesnt seem to be coming from the motor that this valve is probably the culprit. The car shifts rather late and the other symptom is that the car shifts from park to a moving gear HARD. I think the last symptom might be trans or engine mounts but I haven't checked them yet.

 

(Car is an 83 FWD Coupe 3AT)

The modulator basically adjusts the line pressure of the transmission when there is a change in the manifold absolute pressure. Your FSM should have a trouble-shooting chart to help figure out your problem.

If you arre banging into gear, and it shifts late, it sounds like the modulator valve is making the line pressure go too high. Are the subaru ones adjustable? Some domestic ones are.

Yep, I replaced one in a cougar about 10 yrs ago. Symptoms: Tranny was slipping and was late to kick into gear then all of a sudden....BAM (Emeril) there it was in gear. 5-10 minute job on that car. Boz

Cool, sounds like at least many of my symptoms will go away with a new valve. It comes in tomorrow morning. It appears to just thread in.

Thanks for the help!

Easy as pie and works wonders.

Interesting!

 

I don't seem to have one on my 78 automatic. At least not a fancy one. I think all I have is the modulator under the carb, on the front of the manifold and one mounted on top. Just one vac line to the trans. My trans is a bit slow to shift into 2nd. Could this be vac related?

 

Todd

Thanks everybody. I replaced it with one from Advance Auto. $15.38 later I had a transmission that shifted way lower and more normally. The internals on the old valve looked bent when looking thru the little hole.

 

Really liking this car more and more as I own it and fix it up. Might be time for a rear disc brake conversion....just need a donor car (2wd XT turbo).