In case anyone's interested, I've had a Baumann TCU for several years now in my 89 E-350 7.3 ex-ambulance, and it's performed great, worlds better than the stock unit. It's definitely not a plug-and-play deal, but once set up right it works great!

 

That's good to know, we have another member here who runs and E4OD with the Baumann Engineering controller and he's also very pleased with it. Where do you think the Baumann TCU outperforms the factory unit? I'm actually quite happy with the factory setup, the only thing I'd like it to do in a different fashion would be the converter lockup - I'd like it to still lock automatically in 3rd and 4th gear, but when I let off the throttle I want it to stay locked even with the brakes on till the speed drops to 30 mph or the transmission downshifts into 2nd, whichever happens first. I can actually do this with relays as I currently have the converter on full manual control, but it sure would be nice to just program the PCM instead of monkeying with add-on harnesses and what not...

 

Cool, now I won't feel so alone anymore lol. I've never driven a stock E4OD though so its nice to get some feedback from some one that has experienced both versions.

 

You can program it exactly that way, & you also program the speed vs throttle curve for every up- and down-shift. You also have a tow-mode option switch which loads an entire separate program - two TCU's in one. The unit is programmed, and monitored in real time via your laptop computer.

The main gripe I had with my stock one was it would run in 3rd at low load & obviously revving more than high enough to be in 4th, while other times it would stay in 4th under loads that should have had it go to 3rd.

 

I've been running the banks transcommander and it made a huge improvement over stock. Tweeked the TPS to get the shift points where I wanted them and I'm pretty happy with it. Much less adjustability, but its plug and play.

 

I'd lose that TransCommand if I were you - all this thing does is jack up the line pressure through the EPC solenoid, which is not good for the trans, but if you want it you can achieve it with a $2 resistor from RadioShack. All these things they say it does, like sensing driveline load and what not, I don't see how it can do that if it don't even know which gear the transmission is in and what speed the truck is moving at! And believe me, it really don't know these things, as it never even taps into the shift solenoids wires, just the EPC one, which is not sufficient at all of it is to do what it is supposed to do... If you want a real upgrade for your transmission consider and hardware shift kit that goes inside the valve body, definitely not plug-and-play but the results are well worth the hassle. Then for the ultimate control over the whole thing install the Baumann TCU these guys here have.

 

I have a hardware shift kit in mine, and I'm thrilled with it. I get TC lockup in 2nd, all the way down to 20 mph if i keep my foot barely on the throttle.

I would like to remap the shift points, and having a different program for towing would be helpful. Any suggestions on setting up the Baumann TCU?

 

The TC lockup is a computer controlled thing, so I don't think you can have it in 2nd gear unless you have a manual switch wired in - it's my understanding that the PCM will only lock the converter in 3rd and 4th gear. Also in manual 2nd gear you actually get better engine braking with the converter unlocked.

 

Only real catch with the baumann setup is you have to program it yourself. The software package for your laptop (or desktop PC) will come with a set of generic programs to get you started though, so its not like you are starting from scratch.

I would also advise getting the wiring harness that they offer with the controller. Its another $150 (at least it was when I bought mine) but saves a lot of troubles.

Ideally you would also have a laptop PC, but its not mandatory. If you don't have one, a desktop can work but setting the TPS is a little harder and you need to order the AC wall adapter to be able to run it when you have it inside and not powered by the truck 12V system.

There is another drawback. Custom programming can be very habit forming once you get used to the system.

 

A tip here regarding the harness: I went to a junkyard and paid $20 for a scrap TCU, hacked it up and made an adapter for the Baumann (takes some soldering skill and familiarity with printed circuit boards, also the connector diagram). I still have my stock unit and can just put it back in the event of a failure (just keep the TPS idle setting at 1.25V). Valve body mods don't change shift points, except by improving the response time (lag) from the command to the shift. Excessive line pressure increases temperature, and insufficient line pressure will KILL your tranny by slipping clutches. Shifting is controlled by two solenoids - 1st gear: #1 energized; 2nd gear: #1 & 2 energized; 3rd: #2 energized; 4th: none energized. Other solenoids are for: pressure control, torque converter clutch, and coast clutch. The coast clutch provides engine braking in 3rd when O/D is off.

 

I wonder how it would work for a 92 and up with a PCM integrated cluster display. I think in that case, you need the aftermarket and the OEM PCM working together but not sure.

Good info on the shift solenoids. I can never remember the sequence other than 4th is both off.

 

My computer is stock as far as I can tell. I didn't think the TC would lock up in 2nd either until the mechanic friend that sourced my trans rebuild told me that he had it built so it would lock up in 2nd with a touch of throttle. I tried it, and he is right. It will hold engine braking in 2nd with full TC lockup down to 20 mph.

Engine braking is better on mine in 2nd when the TC is locked, and it does not heat up the trans fluid either. I think that is one of the reasons BD Diesel builds the AutoLoc and PressureLoc for use with the BD Brake exhaust brake they sell.

 

Well yes, in an electronically-controlled transmission the VB mods won't change the shift schedule cause they don't affect the solenoids in any way, it's the TCU that fires those. So how do you think Axe_Handle's mechanic made the converter lock up in 2nd gear (the factory TCU does not allow for this) maybe he tapped into some fluid passage that is only used in manual 2nd and rerouted some of the fluid to the TCC? Also the coast clutch in manual 3rd gear ain't enough to slow a truck down or even hold it back down an 8% grade, but it's the same with TCC applied and the CC open - you really need to have the converter locked for maximum engine braking.


Which is why in complete limp mode you still have the OD gear, and not just 2nd - manual 2nd bypasses the shift solenoids entirely, and the moment you put the lever in D you shift straight into OD cause all solenoids are depowered.


You can't do that with the factory PCM tho, so he must have done something to the VB to bypass the TCC solenoid and thus override the PCM's command over it in 2nd gear. Actually how do you know when the TCC applies?

 

I know the TC is locked because when I touch the brake pedal, the TC unlocks and the RPM's drop under engine braking and the engine braking effectively stops. This is the same thing that happens when the truck slows to 20 MPH under engine braking: TC unlocks allowing the truck to coast/stop without stalling the engine.

I can get the TC to lock up in 3rd or 4th when I coast simply by applying any amount of throttle, but I think this is normal.

 

Interesting... are we talking about manual 2nd (you move the shifter to go there), or automatic downshift from 3rd?