ECU tune Transmission control unit?

[longassname]

I still haven't had a chance to write the routines for the ECUtuner software to quickly modify all the shift maps for any gear ratio but I did manually edit the downshift maps for the stick in D for the 4.44 firmware.

[johnboy615]

I'm having my TCU upgrade and stage 1Av1 fitted tomorrow. Can anyone tell me whether I should still drive in 3 round town or can I use D as nature and Subaru intended?

[92 SVX]

Originally Posted by johnboy615

I'm having my TCU upgrade and stage 1Av1 fitted tomorrow. Can anyone tell me whether I should still drive in 3 round town or can I use D as nature and Subaru intended?

your still going to be better off using 3. In d no engine braking occurs and it still shifts into 4th at too low of speed. However with the increased line pressure that the ecutune gives you should not have lots of clutch slipping like the stock does so it shouldnt kill the trans.

[johnboy615]

Thanks for the reply. 3 it shall be.

[longassname]

What did luther campbell say? Throw that d? Put it in D and enjoy. If you drive around in 3 you will have engine braking. You don't want engine braking driving around town unless you really enjoy buying gasoline. You want your car to coast when you let off the gas pedal. When you do want engine braking you can just pull the selector lever back into 3.

[longassname]

Also, just so it is clear to anyone else who may read this, driving with the select lever in 3 bypasses the ECUtune shift maps. Our TCUs are meant to be driven in D. You get the benefits of the line pressure maps and overheat prevention modifications in all the stick positions but you have to be in D to get the ECUtune shift maps.

[Sean486]

Originally Posted by longassname

Also, just so it is clear to anyone else who may read this, driving with the select lever in 3 bypasses the ECUtune shift maps. Our TCUs are meant to be driven in D. You get the benefits of the line pressure maps and overheat prevention modifications in all the stick positions but you have to be in D to get the ECUtune shift maps.

Good to know, I never drive in 3, and had frequently wondered if I was hurting my trans everytime I read the recommendations to "always drive in 3 around town". I tried it but the feeling of the engine braking always made me change it back.

[svxfiles]

UPDATE;
I just got the ECUTune chip for the 4.44 trans installed in my Pearlie, and put more than 400 miles on it yesterday.
I ran it with the Subaru Select Moniter on it AND ran with a GPS to verify actual miles per hour as opposed to the speedometer reading and the reading of the SSM.
The most important differance is that now the #1 speedometer reading
(back of transmission)
now matches the #2 speedometer reading
(front of transmission)
so that there will be less friction in the front to rear clutch pack!
Without the ECUTune TCM the #2 ran a higher MPH than the rear,
say 13 mph front wheels and 9 mph rear wheels.
Now that the car knows how fast it is really going the shifting is delayed as I requested, and I now have the benefit of the higher line pressures.
So, Mike, now I need the TCU replacement chip for the Claret, with the 4.44 ratio and because of the supercharged engine the higher shift rpms.
I think it was 7200 into second and 6500 into third and fourth.
I am putting a check into the mailbox as we speak.
Should I include a check for Nicks valve body as well?
Tom

[longassname]

Having the correct speed calculated from your vss1 actually corrects a bunch of things, like line pressure. An ECUtune TCU with the modifications to match 4.44 gearing is really a necessity for any SVX with a 4.44 transmission.

Originally Posted by svxfiles

UPDATE;
[I just got the ECUTune chip for the 4.44 ......
The most important differance is that now the #1 speedometer reading
(back of transmission)
now matches the #2 speedometer reading
(front of transmission)
so that there will be less friction in the front to rear clutch pack!]

[svxfiles]

As hot as its been here (90°f+) I drove Christine around town lately
(because She has working AC)
Christine is the only SVX that I have on the road with the stock transmission.
It also has your TCU and the Stage 1Av1.
I really like the shifts in it, just so you know.
BTW Nick will be home on August First, after being in the desert for the past six months, and wants me to have his valve body installed by the time He gets home.
The check is in the mail.

[Huskymaniac]

Mike,

The link you provide on your website, and have included on your ebay auctions, doesn't show the line pressure drop below 5% TPS to enable engine braking:

http://www.ecutune.com/images/ECUtun...utyControl.gif

You might want to have those links point to your updated Solenoid A map.

Also, is there a reason why you never answered my question as to why dropping line pressure is needed to enable engine braking? I am curious as to how the engine stays strongly engaged to the axles if the line pressure driving the clutches and bands is so low.

Finally, I did a pin by pin comparison of the TCUs in the OBD2 cars and the TCUs in the OBD1 cars and they look to be nearly identical. There are only a few pins that are questionable or unaccounted for. One says that the OBD2 TCU recieves a MAF signal from the ECU. The OBD1 TCU has the exact same pin connecting to the exact same location on the OBD1 ECU but it is unidentified in the wiring diagrams and pinout I looked at. It is likely that the same exact MAF related signal is on that line. The other two pins/lines that are unaccounted for seem minor. One is tied to a sensor signal ground which is unwired on the OBD1 TCU. Maybe that line was added to the OBD2 TCUs to improve signal quality or eliminate a potential ground loop but it is obviously not needed by the OBD1 TCU and probably has a minor impact on signal quality for the OBD2 TCUs. The last pin/line goes from the TPS supply to the OBD2 TCUs. Again, this is unconnected in the OBD1 TCU. In this case I am assuming that the OBD2 TCU has some logic to verify power is being supplied to the TPS and/or to monitor the exact supply voltage. It probably serves to calibrate the TPS signal and the OBD1 TCUs don't appear to require this signal. In short, it looks like the OBD2 cars can take the OBD1 TCU as a replacement.

There are a few assumptions I made above so if anyone has tried an OBD1 TCU in an OBD2 car and found it to not work, please respond to this posting.

[icingdeath88]

Originally Posted by Huskymaniac

Mike,

The link you provide on your website, and have included on your ebay auctions, doesn't show the line pressure drop below 5% TPS to enable engine braking:

http://www.ecutune.com/images/ECUtun...utyControl.gif

You might want to have those links point to your updated Solenoid A map.

Also, is there a reason why you never answered my question as to why dropping line pressure is needed to enable engine braking? I am curious as to how the engine stays strongly engaged to the axles if the line pressure driving the clutches and bands is so low.

Finally, I did a pin by pin comparison of the TCUs in the OBD2 cars and the TCUs in the OBD1 cars and they look to be nearly identical. There are only a few pins that are questionable or unaccounted for. One says that the OBD2 TCU recieves a MAF signal from the ECU. The OBD1 TCU has the exact same pin connecting to the exact same location on the OBD1 ECU but it is unidentified in the wiring diagrams and pinout I looked at. It is likely that the same exact MAF related signal is on that line. The other two pins/lines that are unaccounted for seem minor. One is tied to a sensor signal ground which is unwired on the OBD1 TCU. Maybe that line was added to the OBD2 TCUs to improve signal quality or eliminate a potential ground loop but it is obviously not needed by the OBD1 TCU and probably has a minor impact on signal quality for the OBD2 TCUs. The last pin/line goes from the TPS supply to the OBD2 TCUs. Again, this is unconnected in the OBD1 TCU. In this case I am assuming that the OBD2 TCU has some logic to verify power is being supplied to the TPS and/or to monitor the exact supply voltage. It probably serves to calibrate the TPS signal and the OBD1 TCUs don't appear to require this signal. In short, it looks like the OBD2 cars can take the OBD1 TCU as a replacement.

There are a few assumptions I made above so if anyone has tried an OBD1 TCU in an OBD2 car and found it to not work, please respond to this posting.

Are the plugs the same?

[Huskymaniac]

Originally Posted by icingdeath88

Are the plugs the same?

From what I can tell, yes. They are given different numbers on the wiring diagrams but, other than those two lines that aren't connected on the OBD1, it looks like the plugs and number of lines is the same.

[steveherman]

Originally Posted by longassname

Thanks,

It has been suggested to me that everyone should have one of these TCUs and that I should do something to get the ball rolling and get them out there so that more people can find that out--specifically it was suggested I have a sale. I thought it was a good suggestion so it's on sale now. The TCUs are now on sale for $199 shipped for the first 10 purchasers.

How about doing another sale?

[Nomad]

I'm selling 2 of these for 75$ each!