350tbi question

[badasshybrid]

I have been searching for the past 3 hours and still cant find anything to help me out. Maybe someone might know whats the problem.

I have an "89" 2 wheel drive chevy, 1/2 ton, that had a 305tbi and 700r4 in it that did run pretty good. I was on the way home and the oil pump went out causing the motor to go out and the tranny to start slipping really bad. I ended up putting a 350tbi and 400 turbo in it. Well, now I cant get it to run worth a shiat. With the brown&black wire to the computer unhooked I have it set on TDC at 0* when you give it some gas it will advance to about 10* or so. But if the hose is on the front of the throttle body to the valve cover it ens up dying, it will not stay running. If I hook back up the brown&black wire the timing advances over to where the mark is straight up on the dampner (at an idle), which is about 2 1/2" for the 0* mark. It will run with the hose hooked up. Now if I try to drive down the road it seems to try to flood itself either way, right before it floods it will bacfire through the carb and valve covers. I am at a loss now I have spent all my money on parts and cant afford to let someone fix this small problem.

EDIT: Also could I put on a carb intake and carb or is there a special intake I have to get?

Any help would be appriciated as this is my tow rig. Thanks

[MrWillys]

Did you re-program it for a 350? Keep the injection, because it's better than any carb.

[Rerock]

I'm sorry I'm not much help as far as the EFI stuff goes (haven't owned a EFI 350 yet); but yes you can swap out the EFI for carb if you got it laying around. Honestly though, I'm sure it's something stupid with the computer or sensors that's causing the problem. Did you swap computers when you swapped motors?

[J Bruce]

The CAL Pak for the computer will be different from the 305 to 350. It tells the computer how much fuel to supply. The knock sensor is also different. If you left the 305 knock sensor in that may screw with the timing (computer will adjust the timing based on bad input from the knock sensor).

[badasshybrid]

I was told that you could use the same computer for the 305 and the 350, I didnt think you could but so I was going by what I was told :rolleyes: As for the knock sensor, I think it still has the one from the 305 in there. I will check.

Thanks for all the info guys !! :beer: :beer:

[Speed Scene Wiring]

The best way to run the 350TBI with this configuration is to reprogram the computer EPROM to a standard shift, you can also order a new STD 350 chip. You should only have torque converter clutch codes in the ecm relating to the 4th gear lockup operation. The overall running condition you are having may be coming from not having a proper VSS signal to the computer. Is the Vss hooked up. if you don’t find a solution quickly to your problem, send me a private message.

[J Bruce]

I was told that you could use the same computer for the 305 and the 350, I didnt think you could but so I was going by what I was told :rolleyes: As for the knock sensor, I think it still has the one from the 305 in there. I will check.

The computer is the same so you can use the same computer for both but under that little rectangular cover (held on by two screws) there is a removeable chip with the fuel curves on it. There are different calibration packs (calpaks) for the various vehicles and configurations GM sells (auto vs manual, suburban vs caprice etc). The same basic TBI computer is used in everything from a Fiero to a motorhome - 4cyl to 454. The calpak is one of the things they use to adjust for the different vehicles AFAIK.