I have an 86 iroc. came with the lb9 tpi 305. has a 350 shortblock with everything else untouched. I keep getting tps and maf codes. and it wont run good at all. ive replaced both sensor and it ran better after I replaced the maf for about 2mins. the the same old **** came back. are the speed dencity setups better as far a reliablity and power goes? and is the manifold diffrent? I may put a turbo on this car later and was wondering if I could still use the speed dencity with turbo. any insights helpful.

try replacing the MAF burnoff relay and trace/check wires for breaks/freying going to the MAF and burnoff relay.

Either system will work for turbo if you have a good FMU (increased boost, FMU increases fuel pressure)

If you are going through the trouble of switching systems and you have boost in mind for future, you are better off adapting a FAST XFI system to what you have.

Why not go with a '749 Sy/Ty ECM?

I also am having problems with the tps voltage since I replaced it. it wont adjust to spec. even if I completly take on off the bolts out It wont give me the spec voltage(.54 volts or something like that?) its been awile since I tryed to adjust it.I forgot the reading.

If you changed to the 350, did you change to a 350 chip, or are you running the 305 chip/Eprom.

Also there are other differences like knock sensor, injectors, and more.

Worn shaft/holes on the TB blades will play games with the TPS min volts.

Just changing to another ecm, without matching/tuning the Eprom to the engine/car will not cure anything.

A perfectly tuned/calibrated chip will not fix worn or broken parts.

idk if they changed the chip or not. I didnt have the car when the swap was done. I bought it after the fact.

Ok, so I pulled the ecm today and instead of the stock stuff, I found a hypertech chip in it. so I would assume this chip was made when the swap was done in 1994. heres the numbers, sn# 197 026
hypertech(c)' 88
pt# 126 002
Idk if this helps at all, but I figured Id post it just in case.