My car used to be an 87 LG4/700r4 combo. When I bought the car in 91 the PO had allready had a dealer installed th350 swap. A few years ago I put in a decent 327 with no ECM controls. Most of the sensors are still there, but no tps. I'm currently looking at putting a 700r4 back in the car to increase my gas mileage. What sensors are actually needed for tcc control? The map and VSS are still there and the ecm is still connected and live. I have a bad feeling I need tps.....

 

What I understand from it, the ECM uses mainly speed and TPS. The TPS is used to modify the point when the TCC locks. You can test if it works by connecting a 3 Watt 12 V bulb from the ALDL connector F to the 12 Volts. This is the drive output for the TCC. When the lamps lits, the TCC should lock. This does NOT include the switch at the brake pedal. That is a switch that switches the 12 Volts to the TCC lock relay inside the 700R4 OFF when the brake pedal is pressed.

 

Why don't you just install a non-lockup torque converter like I did.

Auggie

 

i was told that non lockup in a 700r4 is bad news...but i have had no lockup for over a year now and no probelms yet...but i still am tryin to findout why im not gettin lockup...

 

I think you could get away with not locking up your T/C in town but don't take a long trip at hwy speeds because I think that when the T/C locks up it rerouts the oil in the trany for better cooling and no slippage. I removed my lock-up T/C and just bought an aftermarket standerd type non-lockup conv. and a conversion kit from Art Carr. Man, is the driveabilty ever nice without that lock, unlock, lock, unlock BS.

Auggie

 

Properly setup, the TCC should not be locking and unlocking. I can cruise 80 all day long with the TCC locked. With the stock 305 and 3.08s, I could cruise 80 with no TCC hunting. I would not go non-lockup. The lockup is a better setup, it eliminates slippage at cruise, cooling down your transmission and giving you better fuel mileage, especially when you get around a 3,000 rpm stall torque converter. With the 2,800 stall, I could really only tell a difference from 0-25 mph at part throttle(had to use more pedal/more RPMs to get rolling), which really didn't effect my city fuel mileage too much. The TCC locked cruising down the highway the MPGs were the same. Stab the throttle though and the thing really woke up. I am running a Yank 3,200 (much better than the modified 12" 2,800 stall but is almost $700.00) lockup in my 4L60E, behind my 350 TBI with 3.73 gears and P295/50/R17s. It really moves out well and cruises at 75 with the tach at 2,100. Stabing the gas from a stop causes the tach to jump to about 3,500, the thing leaps off the line, catches second at 5,500, the tach stays around 4,000 and it is up to 5,500 in 2nd before you now it. Now ease off the gas, it goes into OD and lockup and it is back to normal.

 

Fast355, you didn't read my post carefuly. I never said anything about the T/C locking and un-locking at hwy speeds. The hunting of the T/C happens while driving around town which really sucks and the non-lockup T/C has eliminated that compleatly. I also said that I would not drive at hwy speeds with the T/C un-locked which I think could cause trans damage. I have had a non-lockup T/C in my car for ten years now and if there is a loss of gas mileage it has to be very minimal because I just haven't noticed any big change. I suppose I could start checking it again?? I have installed a temp sensor on the trasn. oil pan and the oil temp tends to run the same as engine coolent temp. The Driveabilty of a non-lockup T/C around town is awesome. I would never go back to a lock-up T/C.

Auggie

 

There is really no problem when you install a switch in series with the brake pedal switch. That disables / enables the TCC whenever you like. I did that because my TCC does lock very early making a bad drivability in traffic. At the highway or with a steady speed, I just flip the switch and have TCC lock.

 

I did basically the same thing, except in the Prom. I raised the speed/RPM to enable lockup up some, this allowed the engine to pull at low rpms better, no TCC induced lugging like the stock setup. Yank also promises their TCC clutch will hold up to 450 ft/lbs. Mine is set to lock about 60 MPH, you can feel the clutch lock, the rpms drop about 400-500, and it seems to pull smoother.

 

This is a better option I guess, I could not do that, I am a digital moron.
Please tell me if there is info to reprogram the 1226026 ECM prom to change the TCC lock-up speed. I got very good info from Doctor J at the Vette forum and I am really considering reprogramming to the later standard 44 MPh or more just like you did. But I never did it and I understood that the 6026 software hasnīt been cracked yet due to the low number of people having one. Most upgrade to a newer ECM. May be better but it scares me a little.

 

Well, I put all the lg4 electronics back in, and everything has been working sweet since I posted this. Till the last couple weeks. Now I'm getting an intermittant lock/unlock. No particular speed. Scan tool shows the ecm is doing it too. I also graphed the tps and vss while it was doing it, no dropouts show on the graphs. What else could be doing this?