Potentiometer on the TCU

[Bender]

Has anyone ever thought about putting a potentiometer on the RPM wire going to the TCU? In theory, it seems you would be able to trick the TCU into thinking the engine is at a lower rpm. The more you turn the gain, the higher rpm the car will shift? From there assemble it in a little box, and have a pointer knob on the outside point to different rpms. (8000, 8500, 9000, etc) Then on the street you can turn it down to factory shift, and when racing, you can turn it up to shift at whatever you want.

 

[HighPSI TSi Guy]

I don't think a potentiometer would work well with a pulse signal.

 

[Bender]

Hmm, I don't think it would interfere with the pulsation, just lower the peak of each pulse. I think I'll give it a try in the spring.

 

[mini zilo]

This is an extremely bad idea.

The TCU is programmed to shift based upon things other than RPM. It also uses throttle position, transmission fluid temperature, and a few other things. Using all of these things, it also calculates the proper time to send the signal to the shift solenoids to change the gears, and it also determines porper line pressure. You would be messing up all of the synchrnozing of these things.

 

[HighPSI TSi Guy]

It actually doesn't use RPM at all for shifts.

 

[Bender]

Then what does it use?

 

[steve]

Has anyone ever thought about putting a potentiometer on the RPM wire going to the TCU? In theory, it seems you would be able to trick the TCU into thinking the engine is at a lower rpm. The more you turn the gain, the higher rpm the car will shift? From there assemble it in a little box, and have a pointer knob on the outside point to different rpms. (8000, 8500, 9000, etc)

Great idea if the RPM input was analog but it's not.
It's a set of pulses every rev and the time between the pulses is what's being measured.

This is what the others were trying to hint at.

Keep thinking outside the box, eventually you'll learn how things work and hopefully not loose the creative ideas when your options are limited by reality.

Getting a hold of the DSM technical manuals would help explain how the TCU works. The service manual covers some of it too.

 

[HighPSI TSi Guy]

? Then what does it use?

Output shaft speeds and throttle.

 

[dynatos]

There was a recent thread on dsmtalk about programming the EPROM version of the tcu - someone had made two separate shift maps to replace the eco/pwr maps on the 1g. That would be best, as you could take into account all options..

found it:

Compatible TCU's - DSMtalk Forums

 

[Bender]

Output shaft speeds and throttle.

potentiometer on output shaft speed?

Thanks dynatos. Also, saw you in that thread highpsi tsi..any idea on what model numbers eprom tcu's have? Or do they have the little E in the corner like the eprom ecus? I have a couple extra sitting around here. Also, were there eprom ecu's in the 95's?

 

[HighPSI TSi Guy]

potentiometer on output shaft speed?

Thanks dynatos. Also, saw you in that thread highpsi tsi..any idea on what model numbers eprom tcu's have? Or do they have the little E in the corner like the eprom ecus? I have a couple extra sitting around here. Also, were there eprom ecu's in the 95's?

Hard to say. I"d have to do some more comparing between EPROMs and non EPROMs to see if there is any pattern. I haven't gotten ahold of any 2G TCUs to check out the code yet, I'm hoping it's close enough that I can still sort it out though.