454 TBI to 350 TBI

[mykytiuk]

Hello! I have a '94 K3500 with a worn out 454 TBI with a 4l80e. Chassis and body are great shape. I also have an '88 Burb with a near new from the Chevy dealer 350 TBI TH400. Marginal chassis and body. I am getting ready put the 350 in the K3500. Concerned with what I am going to have to do with the ECM and wiring harness. Both vehicles are complete and running. Going to leave the 4l80e. Just going to swap engines. Can I use the '88 ECM/wiring harness in the '94? Or, can I change the chip and a few connections to make it work properly? Or, do I have to get an ECM and wiring harness and throttle body or other parts from a '94 or so TBI 350 truck? Don't want to spend a lot of time experimenting. Thank you

 

[Team208Motorsports]

94-95 TBI is the second gen TBI ecm usually. Its a red/blue connector ecm. The plugs on the harness will be different at the ecm, IAC, TPS. All knock control is now internal... The best thing to do would be to find the whole module from a 94-95 SB setup. That way if it ever goes into limp its the correct base tune.

You could also reflash the BB setup for the SB but it leaves the error in limp mode, if you ever hit it.

 

[mykytiuk]

Thanks for the info!!! I don't plan to modify much except the exhaust on this swap. I just need it to run the way the engineers intended it to mainly for dependability!!!