4.7 tone ring differences and possibility of ECU reprogramming

[jb3446]

SO i got a 4.7 motor from a junk yard. I seen the engine run so i know it did work before pulling the engine. Had a shop put the engine in. First signs of problems was when they first called me telling me the heads needed to be swapped from my old engine onto the new one because the new one didnt use an EGR valve or something like that but my computer was looking for it. So ok not that big of a deal. They got the heads swapped motor put in wont fire. Shop says that the tone rings are different between the 2. Either i have to swap the tone rings or find the correct motor or rebuild the old motor that died. I found out that the old one died due to the timing chain breaking. From the shop swapping the heads and the head on the one side having no damage to the valves i might get lucky and the other head being ok also. If this is true then any further problems would be contained to the bottom end.

My question is, so the ECU sees the tone ring and it isnt the right amount of blips being sent to the computer and if this is so could the ECU be reprogrammed to see the proper amount of blips ? Or is this problem purely a mechanical one and cant be solved electrically with a reprogramming / reflash ? From what i have read those who have gone through this tackling it purely from a mechanical aspect requires engine disassembly. If i use the engine that is already out i dont need to swap tone rings, just get the bottom end checked out put new timing chain and whatever else is entailed in that job, may as well put a new oil pump and water pump in since itll all be disassembled and thats that. Or rebuild the bottom end along with all that other stuff and have an engine that will last me another 280K miles.

 

[jb3446]

Ohh I wanted to add also that if i end up going the rebuilding engine route, it will be my first time doing so. Any advice from anyone would be much appreciated. Just taking the engine out is gonna be a frustrating process. Pulling the donor engine out was a pain, and we cut the floor out, cut the wiring harness etc to get it out. things i cant do in my truck.

 

[jws123]

What year is your truck and what year truck did the new engine come from? I will need that info to say if its a tone ring issue. If it is a tone ring issue no you have to either get another engine or swap the tone ring from the crank of the old engine over to the new engine which requires crankshaft removal its a pain in the ass but I have done it a few times.