I changed to a Jake's d3 transbrake valve body 3 years ago, right before I hurt the motor, and took the car off the road for 3 years to redo it. Anyway, before it came off the road, I had put it on the dyno, and it tried to downshift, even though I had the shift hysteris set to 0 in the microsquirt. At the track, it shifted much later and was hitting the rev limiter, then before the valve body swap. Fast forward 3 years, I have the car up on jackstands, in low 1, it upshifts to another gear without revving the engine over 3 k rpm. I hooked the laptop up to the microsquirt, with the car idling in drive, or low 1, with the brake applied(no wheel movement) it says that the car is in second, meanwhile I counted the detents on the shifter, so I know it was in low 1. So how do I troubleshoot this?? How do I pinpoint whether it's a mechanical or electrical problem??

 

I'd put it on the ground. I've got my butt kicked more than once trying to diagnose A/T issues on jackstands.

 

Maybe check with Jake’s? Good chance some internal wiring or fluid circuits were changed for the trans brake which affect what the pressure switch sees. Might be as easy as changing the MS settings. Or it could be a bad switch or internal leak.

 

We got that all fixed, what wasn't included in the instructions was changing some internal wiring on the valve body. This valve body is nothing but a headache, car doesn't have reverse once warmed up, unless you bring it up to 1100 rpm. Line pressure is good at idle (140 psi), apparently there is a spring in the valve body, that they added, that applies reverse, and they've had issues with the spring being too stiff. I have now had the pan down 4x, same with the valve body to acesss this spring. They want me to clip another half coil off of it. You'd think for 750$ it would work as advertised. I'm about over it.

 

4 times! I feel your pain. Takes a lot of patience to work through auto trans issues.

 

the showing 2nd on pressure manifold when on the brake is normal for this vb. another thing to note is that you should not use the epc unless just to pull back pressure in neutral, leave it unplugged. line pressure in reverse should be north of 170psi not using the epc

 

Jake's had me add a .040 flatspot in the center land on the epc. I command 100% line pressure in reverse. I even had tried it initially with the aluminum epc bypass plug that Jake's provides with the valve body, and it does the same thing. Btw, after I wired up the additional pressure switch from Jake's it shows first now