rampeyboy
Junior Member
- Joined
- Jul 7, 2021
- Posts
- 1
- Reaction score
- 0
- Location
- Columbia, SC
- First Name
- Boyce
- Truck Year
- Rampey
- Truck Model
- 1991 R3500
- Engine Size
- 350
Guys, I need suggestions on my truck.
It started life as a 1991 crewcab 5.7tbi with 4L80 2wd.
Then I frame swapped it and made it a 4wd. I had the transmission rebuilt and converted to 4wd out put shaft. I drove it this way for two years until the 5.7 blew a head gasket.
Now I have swapped in a carbureted 454. I hooked up the tach wire, I made a bracket and mounted a universal TPS. It reads .1v at idle and 4.94 at WOT. The issue is the transmission only has reverse and first. It does not upshift at all.
I am using the stock ECM, using the original transmission. The only thing that changed is the engine. I went from a 5.7tbi to a carbureted 454 with old school HEI distributor.
My thoughts are either I hooked up the wrong wire for the tach signal at the HEI distributor or the signal from the TPS or tach is the wrong data type(serial vs whatever else they call it). I have thought about simply plugging in the distributor from the 5.7 to rule out the date type sent from the distributor as being wrong. I guess the ECM can control timing well enough for the 454 to run down the street. You guys have suggestions? I see no reason to buy a stand alone computer to run the transmission when the ECM I have has run it for 250,000+ miles just fine What I need is to fool the computer into believing the 5.7 tbi is still in it. Right?
It started life as a 1991 crewcab 5.7tbi with 4L80 2wd.
Then I frame swapped it and made it a 4wd. I had the transmission rebuilt and converted to 4wd out put shaft. I drove it this way for two years until the 5.7 blew a head gasket.
Now I have swapped in a carbureted 454. I hooked up the tach wire, I made a bracket and mounted a universal TPS. It reads .1v at idle and 4.94 at WOT. The issue is the transmission only has reverse and first. It does not upshift at all.
I am using the stock ECM, using the original transmission. The only thing that changed is the engine. I went from a 5.7tbi to a carbureted 454 with old school HEI distributor.
My thoughts are either I hooked up the wrong wire for the tach signal at the HEI distributor or the signal from the TPS or tach is the wrong data type(serial vs whatever else they call it). I have thought about simply plugging in the distributor from the 5.7 to rule out the date type sent from the distributor as being wrong. I guess the ECM can control timing well enough for the 454 to run down the street. You guys have suggestions? I see no reason to buy a stand alone computer to run the transmission when the ECM I have has run it for 250,000+ miles just fine What I need is to fool the computer into believing the 5.7 tbi is still in it. Right?
