I recently bought a truck and was well aware of the big issue. The truck has a 5.3 in it vs the original 6.0. I have had numerous issues, but got it so cheap I thought it was worth a shot to get it up and running. I need to know if having the computer reprogrammed to a 5.3 could be my issue right not. If I hook the computer up to a code reader the vin shows a 6.0. I called the salvage yard that did the swap before I owned it and they said they did nothing to the computer. They just dropped the 5.3 in and watched it drive away. Here is a list of my ongoing issues:

1. Random misfire showing flashing CEL. No loss in power or engine performance issues noticed when this happens.

2. Have replaced crankshaft position sensor 2x and just had it stall out on me again saying it had a failed crankshaft sensor.

Any help is greatly appreciated. I love chevy and couldn't wait to get back into one and as a result I have a 2500 with a 5.3!

 

Having the 6.0 OS run the 5.3 is for sure a problem in itself, not sure I'd be driving it hard at all honestly.

Have you pulled any spark plugs yet or even checked the wires? Can you watch what cylinders are misfiring with a scanner??

It could just a broken/cracked plug causing the misfire problem, it's not uncommom for the plugs to break if it came from a junkyard as they get bumped around alot.

 

I changed all the plugs and wires a few weeks ago to no avail. I don't have a scan tool unfortunately. I thought maybe it was just the computer expecting a different performance level from the engine and throwing a misfire code. Is that possible? I appreciate your response more than you know!

 

Also, the code only flashes when I exceed 2000 rpms. If I stay below that and just drive really easy it doesn't code. Living in the Ozark mountains it is tough to stay below 2k rpms though.

 

It will start up and run but the values will be off. You will also need to perform a crank relearn so it can relearn the cam and crank correlation.

Any time the engine is changed, or those specific sensors are changed the procedure needs to be done. It also helps after a major tune up. This procedure relearns the variables between the cam and crank timing.

This can only be done with a Scan tool capable of OE Bidirectional test capabilities.

 

Thanks for the info 1FastBrick. Do you think this could be the cause of my 2 bad crankshaft sensors? Would the wrong computer have an impact on it as well?

 

Yes, on the sensors.

It's not that the computer that is wrong, but the calibration in the computer is not correct.

It's possible to change the engine calibration to match the engine but retain the Correct Vin number for that vehicle. This can only be done with aftermarket tuning software though.

 

If I were to do a complete swap with a 5.3 computer, would that solve my computer issues or would there still need to be some programming performed? I think I could probably get a cheap one at the junk yard and possible swap it myself as opposed to getting someone to custom program what I have.

As for the sensors, I am going to let the shop replace the cam and crank together and do the relearn on those. Just hate to have to buy a brand new computer or pay for a program if I can just grab a used one.

 

No, The 2500 series trucks with 6.0L came with a 4L80E transmission. The 5.3L in the 1500 trucks would have had a 4L60E transmission. The tables are not interchangeable between the 2 transmissions and you will end up with a truck that wont shift.

Your best option would be to have the current PCM flashed for a 5.3L calibration and retain the vehicles correct Vin number. If the vin number does not match it may not start do to Vehicle anti theft. Also some states vehicle inspection programs require the Vin in the PCM match the Vehicle's original vin.

The sensors likely don't need to be replaced, but rather need a relearn performed after having the engine calibration changed.

 

Do you have a price guess on what they will charge me for calibration? This is all new territory for me. Hoping a simple computer update doesn't break the bank. Thank you again!