I bought a 1991 Trans Am Convertible where it had been under water and it destroyed the 305. And what do you know sitting in my yard was an 89 GTA with a perfect running 350 TPI and trans that I bought wrecked for 200 bucks.

Here is the rest of the story...I paid someone to do this swap by the way.....First of all he put the 350 from the 89 GTA into the convertible and I guess realized some things needed to be changed, one thing he told me he did was he took the plenum from the old 305 and exchanged it with the plenum that was on the 350. After a while I was getting a service engine soon light but that was thanks to a crushed knock sensor wire I repaired. After I repaired the wire it runs a little better but still I hit the gas and i can accelerate faster on my bicycle. Also in the morning it starts and dies unless I hold down the gas for a few minutes and after she warms up its nice.

The fuel pump which was never changed does run for a few seconds after I shut the car off. I tested all the injectors and they read fine. I switched the prom in the 305's computer with a Prom for a 91 350 car. I put in the knock sensor for a 91 350. I put in a new cap and rotor and new plugs and new wires. New fuel filter and air filter also. The only modifications are SLP 1 3/4 headers into a hooker aerochamber catback exhaust. And I think thats about all I can give you.

Any ideas would be great since i've been going insane trying to get this thing running right. Thanks in advance. :hail:

 

The origonal 91 setup from the Vert was a Speed Density system. The 89 was a MAF. Hopefully, who ever did the swap correctly converted the 350 over to the speed densite setup. Do you have a MAF on there? The reason I ask is becasue the SD wirring harness is different than the one from the 89, and will not work with a MAF. Also, the factory PROM origonally in the Vert wouldnt be good for the 350, due do different fuel tables and such. The SD system greatly relies on the computer, so I would start there.
Good luck, and keep us posted!

 

Well all I think he did for that was take the plenum off the speed density 305 and put that onto the 89's TPI setup. I think that is all he changed over, there is no MAF sensor. He connected the MAP sensor to the back of the new plenum but it just kind of hangs there I think he even put on the wrong hose because I can't screw it into the plenum with out kinking the hose.

As far as I know the wiring harness he used was the speed density harness. Everything looks connected right to me but i'll take another look today if i see anything else.

Also last night I pulled out TTS Datamaster and got some logs on it but I have no idea what anything means yet so i'm working on that lol.

Thanks.

 

How about your chip? Is it still the 305 one?

 

Nope i bought and put in a chip for a 91 350 TPI. Thinking that was the problem too but it didn't do much.