I have 2 TPI conversions and have had great success with both. I need a little help from a PROM and computer expert. Perhaps I should post this in C4 but this is really a conversion question.

Background:I have a conversion with a L98 TPI and 700R4 from a 90 Corvette. I have 3.7 rear gears. I have an aftermarket harness and PROM and am running Speed Density with a 7730 ECM and with VSS. I have been running this for about 5 years now with no problems-except 1 nagging issue. The harness is a manual transmission style only with no torque converter control. I have the separate vacuum switch and power from the brake switch to lock the converter. The problem is that at slow speeds-like coming off a traffic light up a small hill-with the low rear ratio the transmission shifts to 4th pretty quickly and locks the converter and it "bogs". I usually drop to 3rd at every light which is a pain, or take off a little faster conditions permitting...

Questions: I wanted to hook up the TCC lockup from the ECM so it wouldn't lock before 40 or so mph, so I added a wire in GF6 on the ECM and hooked it (as ground) to an LED lamp to see at what speed the PROM was set for TCC lockup hoping for 40mph. As soon as I start the car the light comes on so it must be set to 0 mph. Do manual PROMs have a setting for TCC lockup or are they all set to 0 mph? Can I add a TCC speed to a manual PROM? If I add park-neutral and a 4th gear lockup signal, is that the only difference in a manual and an automatic PROM setup? Looks like I need a PROM re-burn in any event.

Any help or advice from a PROM expert? Thanks!

 

Do you have an input going to your ECM for your brake switch? If not you will need to add that also.

 

yes, I do.

 

I changed the 3rd gear switch so that the TCC lock doesnt occur in 3rd only in 4 th. Then used a custom governor setting to control shift into 4th at 45 mph under normal acceleration. Solved all of that upshift and downshift nonsense.

 

I really want the computer to do it. Nobody with experience in manual/auto PROMs?

 

Try Jims Performance...

http://www.jimsperformance.com/

 

I dont know that it is possible with the 700R4 of that vintage. The computer cuts it off cold, but after closed loop, it is controlled by the internal switches. Basically you just want it locked in OD anyway.

 

I want the lockup to only occur in 4th gear, there is an internal switch in the trans for that. I only want lockup above 40 mph which can be ECM controlled like all automatic C4s and F-bodies 90-92 that use the same PROM. My issue is that my PROM was burned for a manual transmission (no park/neutral). My question is whether a manual PROM has provisions for a TCC lockup speed like an automatic PROM or whether I have to add park-neutral wiring and use an automatic PROM.

 

Cant say, dont know, manuals dont have TCC. I do know that the governor can be adjusted to control shift, so, with removal of the 3rd. gear lock up will do just what you want.

 

this is a great forum...lotsa folks burning chips and chaninging things. 730 ECM is quite popular, lot's of knowledgeable people.

http://www.thirdgen.org/techboard/diy-prom/

 

OK, thanks!