currently have a tbi 305. i also have complete 350 tpi intake/harness/etc from an 88. I am going to swap in a new 350 fairly soon but would like to do the tpi swap first so i know everything is working. dont want to be cranking away on a brand new longblock while im trying to diagnose any potential injection problems. my question is will i experience any driveability problems w/ using the 350 tpi on my lil 305 unitll i swap the rest of the engine? will the maf sensor be able to compensate for the larger 350 injectors on the 305 or am i asking for trouble?

 

You don't want to use a '88 system on a '92...you are asking for trouble.

 

care to elaborate on this one?

 

I agree that you're asking for trouble...I swapped my 90 Firebird TBI with a 89 IROC TPI. I ended up buying a painless wiring harness, for a 90 TPI because so much wouldn't match up. You'll end up having to get a custom chip, which is $$$...:nono: you'd be better off with a carb...it'll save you alot of headaches...

 

id rather spend more time making fuel injection work then ever put a carb on

 

i say get a wiring harness from painless wiring and make it even easier for your self, then go get a stock prom from gm to save you time. unless you wanna brn ur own and that is even more of a headache than getting the tpi in there

 

what stuff didnt match up? please give a little more information on that part. i have a complete 88 harness, ecu, and tpi setup that will be going on a new l98 shortblock and afr heads.

 

If you already have the complete harness you should be in pretty good shape.

I highly do recommend getting into prom burning. However, with a MAF set up you would probably be ok to get the 350 running ok.
It all depends on all of the components you are putting in it.. Plenty of info on the swap floating around with search.

I did a TBI to TPI swap on a 90 bird, practically no problems, the only ones were figuring out the speedo wiring and the cruse wiring. Here is a link to the post I made on the topic.
https://www.thirdgen.org/techbb2/sho...hreadid=186359


ps. I would have been up ****s creek if I didn't have my helms factory manual. If you don't have one I would try and find one, greatest help going!!!!!!

 

since you already have a complete wiring harness and are not trying to hack into the stock one, i dont see why the year of the current stuff even matters. the only pitfall i can forsee is that you might have complications because of the 90s elec gauges... but that can be worked out..

anyhoo, i it would run, but it would really run like crap... in my OPINION i would probly put a adjustable FPR on it and crank the pressure down a bit so that it would run a little better until you got the 350 in.

however, you probly should get into PROM burning (or find someone who is) because eventually, you will need a custom chip.

 

thanks for the info. i planned on getting into prom burning anyway since its way cheaper than some aftermarket ecu systems and a hell of alot better than payin someone else for a custom chip.

novass i read your post on the wiring and already copy/pasted it to a notepad file for future reference.

thanks for the help guys.

 

Quite a few wiring issues, you do have a speed buffer so that's ok but where the harness plugs in to the bulkhead connector the pins won't matchup. The throttle cable will need to be from an '88. You have a single fan the harness is for dual fans so that part won't matchup. Then there is the issue of injector size so you will have to get a different prom. I'm not sure on the compatability of the guages because they use different sensors. All and all I would use the TPI but change it over to the speed density program to match your car better. That would mean a different ECU ('7730) & wire harness. I did the swap and just repinned my TBI harness (need manuals wiring diagrams and some indepth studying here) it all worked great.
Which ever way you go good luck,
Don>>>

 

I have a '90 TA that had the TBI and I put in a TPI motor from an '86 into it. I had the L98 longblock, harness and ECM. Let me tell you, it wasn't as easy as everyone says/thinks. There were many electrical problems that came up because of the conflicting years. GM changed several of the important connector on the car between the years. The main one that caused my problems was the passenger's side under-dash connector. This is what supplies the ECM, injector, cooling fans and a few other things with 12v. from the fuse block. Since the plugs didnt match, I had to go ahead and run some wiring to make everything work. And to think that I spent a week trying to figure out why my injectors weren't firing . Oh well.

I am not trying to discourage you in any way. Just trying to let you know what I ran into along the way. Good luck and feel free to ask anything!

 

heres a thought...what about if i block off the csi and use a new gm 92 map tpi harness and get a 730 ecm. in theory would this be an easier solution or will i be getting into a bunch of wirng issues either way. i would like the installation to be as "factory" as possible so all the emissions components and the aldl stuff will still be fully functional...along w/ my cruise control.

been able to find tons of info about tbi to tpi swaps but finding info on keeping everything fully functional has been tough to come by.

again, thanks for all the help guys...keep it comin.

 

That seems like it would work.

 

Jon is your car an automatic or a 5 spd ? That could be another wiring problem you might run into.

 

currently auto but will be throwing in a t56 at the same time...just lookin to build a reliable daily driver/autocross/time trial car. hopefully that simplifies the wiring end of things.

 

You should be okay with the tranny plug then. Mine was a 5 spd and the car i took my TPI set up was out of a automatic so i had to repin the right plug in. So far i have about 50 hrs invested into the swap, and i need to just fine tune it to get it runnung perfect yet. You just run into problems every now and then that take awhile to figure out like i blew an injector fuse which took me like 2 hrs to figure out cause i had just checked the injectors the day before and they all had power to them. And my fan relay had an intermittent problem that wouldn't let the fan kick on. I found out if i would twist the relay in different directions the fan would go on and off. I just had to pull the wires out and squeeze the square prongs tighter to make better contact but that wasted about 2 hours of time too. All i can say is best of luck to you.

 

Yes, I believe that is the way to do it (some others have done it that way) there are still a few wires that will need to looked in to under the dash, but I think this is your best way.
Don>>>