So I think I have asked this on Thirdgen a year or two ago, but didnt get any response so Ill throw this brain teaser out here again as I am about 3 weeks away from starting the car.. (I hope) and hopefully this fits the electronics forum.

I have an 89 iroc that I am swapping basically everything out on and with that I am swapping in an Electromotive Tec II (Yea I know the TEC III is out now, but I started the project somewhere before time began), which has me absolutely salivating, but it does lack a few features..

For example, to lock up the torque converter I will have to use the stock computer because the electromotive has no way to sense what gear the car is in.

Or....

Keeping cruise control would also be something I would like to do and I cant think of any way to do this without keeping the stock computer? Though admittedly this has been my lowest priority so I have virtually no research done on how the cruise control actually works, though I was told it reads the VSS sensor in the speedo.

So....

I guess I am really looking for input from someone who has done something this dumb before. Is it outside the realm of possibility to piggyback some sensors to both computers with no ill effects? For example the TPS? Also, what do you suppose are the minimum number of sensors that I would need to make the stock computer run. Coolant temp, TPS, tach input, VSS? All the FI and ignition related tasks will be handled by the new computer, but how much do I need to keep the old computer in the loop to get the other functions I want?

SB

 

You must have too much time on your hands... Go out and drive the darn thing instead.

I wouldn't know, but if you work the wiring out maybe it can be done. It depends, if the computer is really a binary system, it's not enough to work out the wiring, you would need to work out the laguage aswell. Can you say Fortran or C sharp?

There may be someone who has looked into this, at least the "chip makers" must have given this a thought.

 

Too much time?

I'm just lazy or I would have finished this long ago. I have a habit of procrastinating because I am unsure on how to do something, but a week or two ago I decided I didnt care and will start this sucker with the bare minimum to make it run and fix all the fancy junk later.

I drove a friends new GTO a few weeks ago and missed all the torque I used to have so bad that I went home and started working on the car full force. I have had a zx-6r that has fed my speed addiction, but it is still night and day between that and the 450+ft lbs I am hoping this beast will put out.

 

TTT

No one has seen this done before?

 

The lockup on the trans does not have to have the OEM ECM to work.

The cruise only needs a VSS input to operate, not the ECM.

No need to have a remote NASA tech center in you car for 2 simple functions.

I'm sure trickster has diagrams onhand but, the trans solenoid only needs 2 powers in and ground controls the lockup.
W/o ecm, a switch to ground would give you manual control of the lockup function.

CSame deal here with the diagram.. the cruise power is controled from the multifunction lever. it's tied to a switch on the brake to kick it off. The only input it recieves is the speed signal which, comes from the VSS buffer. In pre 90 camaros, it's on the back of the speedo head. Birds.. seperate buffer box that reads the VSS and then sends the signal to the speedo and one tot he ECM.

 

Try this for the TCC. www.technicalevolution.com/700inst.htm

 

There are a few kits that can do the TCC as a function of speed by sensing the speedo cable and routing the engage power through the 4th gear switch if you only want it to come on in hi gear. Otherwise it comes on in any gear at the set speed. I have a complete B & M setup that I took out of my car. Send me a mail if your interested.
The cruise control is a 2000 pulses per mile signal IIRC that is output by a buffer box or directly from the ECM. depends on year/make.

If your looking to keep it simple, forget the cruise and put in an aftermarket TCC speed switch. If your willing to go into depth of using two computers IMO you would be better off spending the money on chip burning equipment and using a GM ECM to run the whole thing. Having multiple computers is the exact reason I tore my whole system out.
Diagnosing a problem was downright impossible due to the guessing involved. My situation was a little different in that I had fuel control on one end and everything else on the oem unit (LG4 CCC) converted to TPI.
Now Its totally rewired GM stock 730 SD and I'm much happier with the reliability and tuning that I can do with it.

The TCC setup is very subjective to how YOU drive and I personally like to be able to tweak all of the settings for lock/unlock to suit my bad driving habits.
Just my suggestion.