hey guys looking for some help here im taking my 305 TPI L9 out of my 1991 z28 and replacing it with a l98 350 TPI from an 89 Iroc. what I have questions about is the electronics as far as the ecm and "PROM" are concerned. I aquired the ecm out of the Iroc(donor car) but as I have read the computer system between the 89 Iroc and the 91 z28 are different. what do I need to do to make the new setup work? Do I need to use the ecm out of the Iroc somehow? Reuse the ECM in my 91 z28 or have one of them reprogrammed? any help would be greatly appreciated......

Thanks in advance for any help guys!

 

Reuse the ECM in my 91 z28 and reprogram the PROM.

 

So the ECM that I currently have for the 305 TPI can be used for the 350 TPI? If so is there anyone on this forum that can reprogram it or is there a company that makes proms for this sort of thing?

 

Use the sensors and all the electronics from the original 305... Technically the 350 uses a different knock sensor, injectors, and PROM, but the 305 parts will feed the engine fine it just wont be ideal. 90-up TPI cars are speed density instead of MAF, so the early chip won't work in the later computer, and the GM 90-92 L98 prom is hard to come by. Get it running with the 305 stuff, and start watching the classifieds for the PROM and whatnot that you need to set it up right.

 

Also 305s used 19 lb injectors and 350s used 22 lb. I dunno how that will affect the fuel maps.

 

And if you don't know , you need the plenum off the 91 because the 89 plenum does not have provision for mounting the MAP sensor used on the speed density system

 

thanks for all he help guy but the big question to all is what about the computer? can it be reprogrammed? is there anyone capable on here of doing it or is there a company that does it?

 

ttt