missing auto ecu but have a m/t ecu

[brandonclum]

OK guys just picked up a 91 auto fwd tsi for 200 bucks ya couldn't pass on it question is does the m/t ecu work for the auto as well i know dumb question just have the m/t ecu also if not anyone know where i can get one?

 

[92DSMErdrick]

I would assume so. The TCU is what controls the transmissions shift points. I used an AUTO ecu in a M/T and it worked so I don't see why it wouldn't vice versa. The only difference is timing maps between M/T and AUTO.

 

[mitch rich]

Yes. it does work. I put it in when I have my 1g auto. Then I also threw in the manual 450s and it worked great.

 

[MY1GDSM]

The only difference is timing maps between M/T and AUTO.

Not true, there isn't a major difference. But there is a difference. About 30cc's worth of fuel.

5spd Ecu's are setup for 450cc injectors and 37psi base pressure, Auto Ecu's are setup for 390cc injectors and 43psi base fuel pressure. Aside from the maps that is about it. It come out to about a 30cc difference because of the lower pressure 5spds run... as long as you have a good working o2 the car should run Okay. Though the Fuel trims might Max out from the fueling differences.

 

[brandonclum]

OK thank you guys ill give it a go. Anyone know where i can get a auto ecu tho the 30cc difference scares me a ted hoping for 18-20lbs boost.

 

[BLK97AWD]

It will be easier and better to get the 450cc injectors. They're everywhere.

 

[constant_proj21]

OK thank you guys ill give it a go. Anyone know where i can get a auto ecu tho the 30cc difference scares me a ted hoping for 18-20lbs boost.

Uh, don't run 18-20lbs on 390's.

 

[5150DSM]

I've been running a M/T ECU in my auto for a couple of years now, along with the 450's. Ran it with the Evo injectors and MAFT too. Actually, I'm still running right now on my built motor. No problems so far. (Not with the ECU anyway)

 

[brandonclum]

No I wouldnt run that much boost with 390's i plan on going with 650's or bigger.

 

[steve]

The only difference is timing maps between M/T and AUTO.

Another difference is that the auto ECUs understand that putting the transmission into gear puts a load on the engine that doesn't happen on a 5 speed and the code for managing the idle is different to deal with it.

 

[steve]

Not true, there isn't a major difference. But there is a difference. About 30cc's worth of fuel.

5spd Ecu's are setup for 450cc injectors and 37psi base pressure, Auto Ecu's are setup for 390cc injectors and 43psi base fuel pressure. Aside from the maps that is about it. It come out to about a 30cc difference because of the lower pressure 5spds run... as long as you have a good working o2 the car should run Okay. Though the Fuel trims might Max out from the fueling differences.

If the pressure is really what's quoted in the FSM it's about 411cc effective at 36.3 psi vs about 386cc at 42.7 psi so say a whole 25cc.

 

[brandonclum]

OK dumb question alert! If the m/t ecu works then how does the auto tranny know when to shift. sorry been out of the car world for about 5 years now drawing a blank.

 

[steve]

The TCU controls the shifting of the transmission. It shares sensors with the ECU but doesn't communicate directly on a 1G, I don't remember if there are torque reduction request and command on 2G ECU like there are on the V6 cars and it's dinner time so I'm going to eat rather than look it up right now.

 

[brandonclum]

i feel ya there thanksfor the info