I know this is probibly a really stupid question, but will the ECM in my 91RS (305TBI) run a TPI350? I have never changed an ECM, if required, what is involved? Do I have to change any wiring, or will it just plug in? Thanks for your help. ------------------ 90 RS T-TOPS 3.1 V6 RUNS STRONG AT 187,650 ON ORIGINAL ENGINE Just got A 91rs W/blown 305, this is my first project car.So, I really need advice.ANY is appreciated!

I believe the answer is NO, the ECM is different. The ECMs used in TPI setups are a little more sophisticated than the ones controlling TBI motors. This doesn't necessarily hold for ALL platforms, though.. I found a '165 ECM, the same one as in my '86 305TPI, in of all places but a '91 S-10 4-cylinder "work truck".

You might want to move this over to the PROM message base if you want a definitive answer, I'm not 100% sure about the '90-up motors that do not use the '165 ECM, but for '86-'89 TPI I'm pretty certain the ECM is not compatible. Note that 305 TPI and 350 TPI for the same year will use the same ECM, though.

the reply as before is no they will no.
the injector driver in the tbi unit will not
have suffient power to drive eight injectors.
some of the aftermarket manifold companies
manufacture a pfi setup to use your existing
computer, and with some good output. but for
overall performance, drivability, and dependability
id swap ecms...
airdeano

I have heard that the ECM from an eary 90s MPFI V6 (Lumina, Corsica) is the same as the TPI Speed Density ECM.

this page should help identify the different applications: http://www.diy-efi.org/gmecm/ecm_info/