1979 GMC Dually TBI swap

[Randy 79]

Update time. Truck had a good test this past week, took it out to Lincoln, NE for the Solo Nats, pulling my 28 ft enclosed trailer with the Camaro in it. 2100 mile round trip.

Truck pulled great, had plenty of power and climbed hills without needing to downshift. No check engine lights at all on the trip. Cruising speed was 65-68 mph which was in the 2600-2800 rpm range. Overdrive would be nice to have to lower the engine speed. Coolant temps stayed in check, even with temps in the mid 90s.

It seems the 7060 computer is fairly tolerant of not having a 4L80E hooked up (manual trans in truck), just a VSS from JTR is hooked up. I only had one issue a week before I left, got a code 13 for O2 not responding. Swapped out the heated O2 for a 1-wire O2 (due to time constraints) and all was fine. I guess having the heater on all the time may have been too much for the first O2 sensor. I still have everything there for a heated O2 if I need to go back to one later.

[Randy 79]

Well, this will be the final update to this build. Sold the Dually Saturday (8/1/15), it is in its new home in South Carolina. I did tell the new owner about this site so maybe he will join in. Hope it works out great for him.

I will still be around though, with the new to me '03 Suburban 2500 and my other vehicles, I will still be messing around with EFI stuff.

[1project2many]

Well, this will be the final update to this build. Sold the Dually Saturday (8/1/15), it is in its new home in South Carolina. I did tell the new owner about this site so maybe he will join in. Hope it works out great for him.

I will still be around though, with the new to me '03 Suburban 2500 and my other vehicles, I will still be messing around with EFI stuff.

It sounds like you've had plenty of fun with the truck and I'm glad you found this site helpful. The truck is a great example of an EFI retrofit and I'm sure it will help other people considering the same swap. We can always use OBDII experience so please keep in touch!