My car has a 305 TPI with a 4L60 trans, I am going to a 383/stealram, if I want to use the Commander 950, I've heard that I'll have to "piggyback" it to my ECM. This is for transmission functions controlled by the ECM I believe. Maybe for the speedo and all that, too. But anyways, can somebody point me in the direction of some detailed info on this subject??

 

if you have a 4L60 (just a renamed 700R4) you shouldnt have any problems at all with eliminating the stock ECM altogether, as the ECM has nothing to do with trans function in that case, except TCC lockup. TCC lockup can easily be rewired with available kits from TCI, B&M, or any number of other manufacturers. if you are running a 93+ 4L60E with a 305 TPI, i'd love to know how you got that to work since the 4L60E was never offered with a 305 other than the TBI 305 installed in light duty trucks.

 

It is a 700R4 trans, and thank you for the info regarding lockup, just trying to make sure that I will not need the stock ECM also.

 

I too am using a 700r4, and a Commander 950 for motor control.

Do the TCI and B&M use a VSS signal, or another method? I have a Corvette 700r4, which I understand permits locking the converter in high gear at full throttle. This may be done through the original ECM, do these aftermarket provide this capability?

How do the aftermarket perceive optimum speed (or load) for lockup?

 

the aftermaket units AFAIK use vacuum switches much like the factory units do. when engine vac gets to a certain point in high gear, it allows the current to flow through to the TCC solenoid which locks the converter.

 

Which vacuum switch is this?.
Some use a max LV8 for one parameter for TCC.
Usually the TCC function uses a min cooolant temp., a min and max TPS value, compared to MPH, enables depending on which gear your in. The aftermarkets that just use vac, that I've used were the crudiest things I've ever used. The adjustment screw is either on at the wrong time or off at the wrong time.

Using a Romulator with a stock ecm gives you on the fly tuning, just like the aftermarkets, the alledged advantages of aftermarket are min., IMO.

 

So, Grumpy, are you saying that I would just be better off getting myself a romulator and keeping the stock ECM? I don't want to lose any functionality and I don't want two computers in my car, or have to pull my check engine bulb. I hate butchering up cars.

 

 

thanks for the help 614, not quite sure what means, but cool.

 

i've worked with several factory setups, and they seemed to work without computer assistance (TPS, etc) maybe GM changed them with TPI cars? its been so long since i've been under the hood of my TA, i dont even remember what my valve covers look like.

 

Since I am going to be swapping my engine anyways, should I just switch over to the 730 ECM and get a new harness for SD? I have MAF right now, but I think it might limit me a little, especially when it comes time to supercharge this engine.

 

Do any of the aftermarket controls for the lock up converter actually use a speed sensor rather than a vacuum switch?


If not, is the original ECM the only way to go on this?



Staying with the Commander 950 for engine control.

 

You've really answered your own guestion here.
The only way to do what you want is by using a stock ecm.

Just as a side note, I was hooking up a Gen VI to play with. Inadvetantly I missed a jumper on the adapter harness, so the MAP sensor didn't get it's 5v. Without any self diagnostics, trying to find out why the ecm would freeze at a 3.1 msec PW, was a pain to figure out. And with all of them in service, and on a lits we're there are a number in use no one knew about the MAP error default of 3.1 msec.. And the burn date on the chip was 96, so they've been doing this for a while.

While the aftermarkets offer an ease of tuning, it's just really a lack of sophistication, and that's what makes a car lots of fun to drive, IMO..

 

right now lockup is controlled by a switch in my console by the window switches. Soon it will be simply a "Hobbs switch" that ground the 700R4 when it sees over 13" of vacuum, such as during cruise. The only other option is to use an internal vacuum switch, B&M and TCI offer them for like $120 i think, but they do the same thing as a Hobbs switch would. only the hobbs is alot cheaper. and you can always change it...

But the switch method is fun because I like to lock it up before i get into the throttle, it makes tuning easier at certain low speeds because you can get to lower RPM Load points on the map where normally the TC would stall past.