Xenon
02-25-2012, 08:26 PM
Ok, a little backstory and then questions that will no doubt demonstrate my ignorance.
Got this 'burb in '09. Had a burnt up 5.7l (worst seized engine I ever saw, ran with no water in the radiator)
I got a 400 to put in and decided it'd be neat to go EFI. Put all the tbi components on the 400 exactly as they came off the 350, not quite knowing what I was doing. It ran rather well, had a dead spot off idle and never quite felt like it was putting out as much power as it could until above 3000 RPM. got 10-12 MPG highway, which I thought was stellar for a 7500 lb truck with 4.10 gears. I attributed the less than perfect performance to the fact that it had the stock 400 cam designed for a carbureted engine, something I had overlooked when I put it together.
Somewhere around Feb. 2010 the truck flat died going down the road. I immediately suspected the ECM, as I had been experiencing rough idle, severe surging (45mph to 65mph and back without moving the accelerator) and excessive fuel consumption (5mpg)
The ECM1 fuse was blown. There was no fuel coming from the injectors. It had spark though, it would kinda cough to life if you sprayed alot of ether in it.
Replaced the fuse. Nothing. It did not blow again though, which ruled out a shorted wire in my mind. (EDIT: In my thinking, it ruled out a shorted wire. It in no way ruled out a shorted wire in my mind...)
I was very short on money at the time, I was in Arizona and trying to save up to come to ND for work... So I took a weekend and put a Holley on it with the carb'd manifold that had come on it.
It's never been the same without TBI. doesn't have the power it used to, gets 7mpg uphill, downhill, headwind or tailwind.
I have the time (and some money) to put into it now, as well as a '98 Suburban to drive daily, making this somewhat of a project truck now.
I am here, of course because I want to put TBI back on it, but I want to do it right.
I have the original TBI components off of it, and the TBI components off of a near identical '88 K20 Suburban that I scrapped out for a guy a few months ago.
I have 2 1227747 ECMs, one that I believe to be bad (the '87) and one that I assume to be good, but don't actually know.
the '87's ECM has an AFCB prom and the '88's ECM has a ADYR prom.
My basic idea was to put a 1987 5.7l cam in and put the ECM from the '88 in and plug it all back in.
Please point out all the flaws in this idea and offer your better ideas.
Got this 'burb in '09. Had a burnt up 5.7l (worst seized engine I ever saw, ran with no water in the radiator)
I got a 400 to put in and decided it'd be neat to go EFI. Put all the tbi components on the 400 exactly as they came off the 350, not quite knowing what I was doing. It ran rather well, had a dead spot off idle and never quite felt like it was putting out as much power as it could until above 3000 RPM. got 10-12 MPG highway, which I thought was stellar for a 7500 lb truck with 4.10 gears. I attributed the less than perfect performance to the fact that it had the stock 400 cam designed for a carbureted engine, something I had overlooked when I put it together.
Somewhere around Feb. 2010 the truck flat died going down the road. I immediately suspected the ECM, as I had been experiencing rough idle, severe surging (45mph to 65mph and back without moving the accelerator) and excessive fuel consumption (5mpg)
The ECM1 fuse was blown. There was no fuel coming from the injectors. It had spark though, it would kinda cough to life if you sprayed alot of ether in it.
Replaced the fuse. Nothing. It did not blow again though, which ruled out a shorted wire in my mind. (EDIT: In my thinking, it ruled out a shorted wire. It in no way ruled out a shorted wire in my mind...)
I was very short on money at the time, I was in Arizona and trying to save up to come to ND for work... So I took a weekend and put a Holley on it with the carb'd manifold that had come on it.
It's never been the same without TBI. doesn't have the power it used to, gets 7mpg uphill, downhill, headwind or tailwind.
I have the time (and some money) to put into it now, as well as a '98 Suburban to drive daily, making this somewhat of a project truck now.
I am here, of course because I want to put TBI back on it, but I want to do it right.
I have the original TBI components off of it, and the TBI components off of a near identical '88 K20 Suburban that I scrapped out for a guy a few months ago.
I have 2 1227747 ECMs, one that I believe to be bad (the '87) and one that I assume to be good, but don't actually know.
the '87's ECM has an AFCB prom and the '88's ECM has a ADYR prom.
My basic idea was to put a 1987 5.7l cam in and put the ECM from the '88 in and plug it all back in.
Please point out all the flaws in this idea and offer your better ideas.