Hi I have a 92 firebird with the 305 TBI and was wondering if anyone out there knew about or has converted to TPI. The engine I have right now has headers and no smog system. Also I don't mind changing manifolds and such and can get the stock TBI setup for fairly cheap (wiring harness, prom, ect) What I was wondering is if there is an easy way to just change a few pins in the computer harness or something and just plug stuff in or if I will have to gut the dash and engine bay harness and rewire everything...

 

I am just about to finish my TBI to TPI swap, have to run some vacuum lines before I can start the motor. You can use the TBI harness, but it will have to be converted. This is not just a matter of a few wires, their are several companies that will do it for you for around 300(I think that’s what I saw some charging). The easiest way to do the swap is to find a harness form another car. That’s what I did. All you need is the engine harness and the ECM, the dash, AC, and turn signal wiring stays the same. You can either get a Speed density harness or one that used MAF, either way a used harness and ECM shouldn't run you more than 200. Speed density tends to be the rarer and more expensive of the two. This is just the wiring aspect of the conversion, you will also need the manifold, plenum, runners, throttle body, injectors, fuel pump, and sensors.

 

ok, im considering the same swap. I can get the throttle body, runners, plenum, manifold with egr, fuels rails, ECM, complete wiring harness and bolts for $400 delivered to me. This isnt exactly related to just electronics. I have an '88 car and would be going with the '86 TPI. I'd really like to do this but I'm wondering how much is truthfully involved. I know im going to need the induction work for the MAF and some of the other sensors but do i need all of them, TPS, oxygen sensor, MAT(manifold absolute temperature)? JR305, if youd be willing to help i have alot of questions i need to ask.

 

Sure ask away, if I don't know the answer someone on this board will. As far as the swap, it is a big swap. It’s pretty straight forward though. 400 for pretty much everything sounds like a good deal, make sure it comes with a MAF sensor (I think they are fairly expensive). When doing this swap their is always the chance to run into electrical problems. Which in my opinion are the worst types. I would not attempt this swap on a daily driver for that reason. I am about to try to start my engine tonight and hopefully won't run into many problems.

 

the car is a daily driver, but i have 2 weeks to get it done. hopefully working all day over a weekend and possibly a monday and tuesday i could have it all together and ready to go. drive it for the rest of the week and try to get all the tweaks out of it. during the swap id be doing SLP headers, wiring in dual fans, with one just wired to a switch in car and a few other miscellaneous items. Before i put the TPI on the car would it be worth having the plenum ported? and from what i have come across the fuel pump seems to be the biggest problem for people but i dont know.

 

JR305 thanx for the advice, this is a daily driver and although I am good with wiring there is ALWAYS something that dosn't go right so I think I'll hold off. I'm planing on having a custom multiport system made for my 79 Formula with a 400 Ram Air III pontiac block in the next year or so and will be installing it myself I think I'll wait untill I do that and maybe just drop a 350 with a holley stealth ram or something in my 92 later.

 

well i just got all my TPI stuff today...so saturday we're gonna attempt the swap...i've been told that we shouldnt run into any problems but that electrical thing kinda worries me its all painted purty tho..i'll get pics for y'all once its done

 

well...finally...its done...it was a ****in nightmare jus cause my buddy that worked on the wiring ****ed up a ****load of stuff...all is good now im jus chargin the battery...ran into a few misc. **** that i needed cause tpi cables were a lil longer...other than that i'll be drivin her tonight