I double checked the base timing and it is where it should be. It is a 1985 IROC with TPI, I removed the 700R4 and replaced it with a T-5. Car runs great at low rmps, while accelerating and at idle. The issue is in the 2000-2500 rpm range above 35 mph under light load. For instance, at 70 mph the car runs fine on the climb to 70mph, but after a minute at constant speed the engine will surge with a slight misfire. If I accelerate from this point, it does fine. It just doesn't handle a light load well.

From what I've read, the fuel and spark tables are different between the manual and automatic transmissions. Is it an option to have the EPROM with one that is programmed with a manual transmission configuration while using the 1985 ECM? It is just an occasional daily driver and I'm not looking to tune it to set world speed records. I'm looking for a solution without having to buy tuning equipment and all the miscellaneous equipment.

Thanks in advance...

 

I beleive is is more than SA tables. It may also be throttle follower routines and gear ratio diffs.
The best way is to down load tunerpro(free) and witness the differences between the auto and manual .bins. Bins are available at craigmoates and gearhead. you will need to search for the the appropriate broadcast codes.

tpichips.com may offer a solution.

 

you should junk that 870 and goto a 1227165 ecm. depending on your maf #'s you may not need to get a different maf. the 870 uses a 2732 eprom and the stcok one is more than likely a Otp.

http://www.eecis.udel.edu/~davis/z28/ecm_swap/

 

I don't believe that a manual trans was a option in 85 There are all the bcc I know for the 870 tpi in 85. HlH, HLK, HLL, HLN, HLP,HLR, HLS

 

Correct. I believe the first year for a manual transmission for a TPI engine was 1987. Most likely, I'm going to have to upgrade the ECM is what it is sounding like...

Are ECM's from that era easy to find?

 

16198445, 1227165 ,16198259 The ecm is easy to come bye. The memcals are a little harder to find a 87-88 manual trans memcals. It would be best to just find any 86-89 tpi memcal and remove the vats in the programing and use a $6e tune that of 89 remove the ninth injector and gain a lean cruise mode.

 

I have a lot of reading and research to do now...

 

maybe start with a Apyx bcc. gm 16133478

 

you can pm me, I have a few maf memcals and can assist with reprograming.