08 5.3

has anyone done a swap using the 08 ecm, i had my ecm and tcm tuned by Nelson. doing my wiring harness myself, tried to fire it up today, can not get any fire to the coils or injectors, the elec throtle works and it has 57 lbs of fuel pressure, it cranks over fine, but no fire! i am wondering if I have to have more controls from the original truck, or if i am just missing something. I have the helms manual and i have hooked up all the wires that I had with the original harness, the engine is an 08 5.3 with 4l transmission, all stock except headers, any ideals? have checked all grounds and they are good, checked ground all the way to each coil and it is grounded good.

I'm sure you have checked the grounds and I don't wanna insult because I have yet to do one of these swaps but I spent two weeks chasing wires over the internet for another member that doesn't need us any more because his stuff runs after finding a ground fault to the coils (open circuit voltage confused him). Let's really make sure you're good there.

x2 one missed ground will kill everything ask me how i know :lol:

if i check the coil plug, i show to have ground, low ref ground and 12 volts, but never get the 12 volt signal, so if i have a bad ground, it will cause it to not give the signal in all 8 coils and fuel injectors? what do you have to do, do you need to check resistance of every ground, from the coil back to ecm pinout? never had a problem like this so not real sure how to check the right way thank you

I see now the injectors don't work either...this leads to a CKP (crank sensor) issue. Sorry I didn't see that before. You got a scanner to read RPM while cranking?

no scanner have a code reader but that is it. could it be that maybe the vats didnt get removed, or would that just kill the fuel..

striped all wiring out of tape and could not find any bad wires, check cps wiring had 5 volt and ground as should be, did key relearn 3 times, still no fire or fuel 12 pulse. i am lost!

did you verify if VATS/PASSKEY was disabled in the PCM?

sent ecm back to nelson to see if anything was wrong with it.

got my ecm back from nelson today, put it in and fired right up!!!!!!! thanks for everyones help. very quick return from nelson on the work!!!!