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vortec 4.3 to vortec 5.7

791 views 2 replies 2 participants last post by  williamashworth 
#1 ·
Okay I'm new here and I hope this is where I need to be asking questions. I'm sure this has been covered here before but I couldn't find anything. I'm helping my dad swap his work truck (96 k1500 W/T vortec 4.3 4L60E) to a vortec 5.7 out of a Tahoe. The motor was running and driving before we pulled it out of the Tahoe. We got it all swapped over and now we're not getting and fire. He has replaced the distributor, coil, crank sensor, cam sensor, and ignition module. I'm sure I've forgot something. Any help or info or a link to this topic if its been talked about already. TIA
 
#2 ·
What was the extent of the install? Is it safe to assume you moved the harness, ECU, etc. over to the truck from the tahoe? The 4.3 ECU won't run the truck. My second suspicious, if you moved the ECU, is something to do with the RFID lock in the column not talking to the computer.

If you did swap ECU and you're positive the computer isn't preventing the motor to start you need to check the 3 main components. I wager you're getting air flow. you don't mention the year of the Tahoe but I suspect it's probably drive by cable. Which mean you need to check fuel delivery and spark. I would just spark first as it's a smaller system. If you don't have spark look at the ignition components. Keeping in my mind spark is what the ECU turns off if the computer detects an invalid key. Lastly I would look at the fuel delivery. Do you have pressure at the motor? There should be a test port. Again, you don't mention the year of the Tahoe but It's probably fuel injection so you should be in the 60PSI range.

If you didn't swap the ECU i would start there.
 
#3 ·
Sorry I knew I would forget something. The Tahoe was a 97. Both are drive by cable. Yes we swapped the ECU, harness, and even the steering column too. Neither of the vehicles have chipped keys. If that would make a difference beings we swapped the steering columns too. We are getting fuel to the intake just not getting fire out the distributor. TIA
 
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