Can anyone point me to a website, or give me directions on what needs to be done wiring/programming wise for my 94z28? I'll be installing a th350, and need to know what wiring has to be done to the harness(if any) and any tuning/programming...i have lt1 edit already...

 

You won't be able to use any of the A4 harness, that I'm aware of. The th350 is fully mechanical. Basically, you need to install a stock M6 program and make the changes to make it look like your current tune (spark advance, fueling, idle, etc.).

 

Sweet that's all i needed to know, i wasnt sure if a m6 file would mess with the pcm.

 

All I did was turn off any trans-related trouble codes. No need to install the 6-speed tune. The toughest part was playing with the speedo' calibration factors to get it to work right with the new pickup.

Mike

 

If you run the M6 program, you will probably have a problem with the VSS. I don't know what VSS you plan to use on the TH350, but the mid-90's GM truck VSS that I used on my TH400 put out a 40 pulse/rev signal, and that's compatible with the A4 programming. An M6 program looks for the 17 pulse/rev signal from the M6, making the speedo read 2.3 X the true speed. One solution is the Dakota Digital speedo interface, which will convert the VSS pulses, or using an A4 program with the tranny interfaces deleted.

 

Thanks Fred, any info I get from you is always useful.

 

If you did use the M6 program (which I don't think you should do), then you could correct the 2.3x error by offsetting with gear ratio/tire size changes.

 

Did OBD2 LT1 PCM's utilize torque management? Ii am wondering how installing a trans other then a 4L60E would perform. If the PCM pulls timing during a shift (or when it thinks its shiftin) and you have some other transmission, I think there could be some fairly strange out comes.

I am helping a friend with a 97 LT1 swap. He is using a 5spd that come in his 1994 Pickup. The current tune on the computer is for a A4. I have disabled trans related codes, but It sill drives very strange. I just found a M6 tune i am going to try out.

Other things I have found different are Decel fuel cut is different, as well as some Idle Air Control settings.

I have a 730ecm TPI 305 with manual code, with a TH400. i noticed the IAC is very slow to come on when I shift into gear, or when I shift to park its slow to go back to target Idle. The auto trans code moves the IAC quicker.

My thoughts are try out a M6 or an AUTO code and see what works.

 

I have not seen torque management tables in the OBD2 LT1 PCM. In fact, the OBD2 LT1 PCM's table list is almost identical to OBD1 LT1.

Interesting point on the return to idle. I do know the auto transmissions have both an electronic range indicator in the transmission and an external park/neutral indicator switch which is an active signal to the PCM the transmission is indeed in neutral. The external switch is used by the PCM to set the idle speed (changing the switch state changes between the park and drive idle speed settings in the PCM). The manual cars would not have this (although they do have the clutch pedal indicator).

 

Does he have his VSS hooked up and working correctly? The car won't go into closed loop if it's not get the signal.

 

Getting hooked up tonight.

It does go into closed loop, just it thinks its in the IDLE cell all the time.

 

Mine ran horrible when I had mine like that. Mine kept trying to go into closed loop and then would kick back to open loop.