Had a friend who is an independent professional mechanic install a DOD delete kit on a 2017 GMC Sierra Ecotec 5.3L L83. He has done several others but on LS style engines and not the newer ones. Install went fine, had to replace broken timing chain tensioner also.

So when the truck was started back up, it ran very poorly. There are 11 codes including P0090 Fuel pressure regulator control circuit, P00C6 Fuel pressure low, P00C8 Fuel pressure regulator solenoid supply voltage circuit open, injector 2,4,6,8 circuit open (P202, P204, etc). P0300 Random misfire, P0324 knock control system error, P0341 camshaft position Sensor A circuit Range/performance, P050D Cold start rough idle.

He did have the software updated to include the DOD delete before initial startup. He's diagnosed it to the best of his ability and cannot find anything. He got some advice from a GM tech and they both think it needs a new ECU with all these seemingly random codes that don't make sense with the work he did being all mechanical. He did find that the existing battery had a dead cell, so it was replaced. I am hopeful it is just the ECU but wanted some other opinions. I did order a plug and play ECU that has a warranty.

My only other thought so far was that if the fuel pressure sensor and/or regulator are somehow bad or disconnected that it would cause the injectors not to fire and misfires, etc. Basically either of those might cause all of the other codes. Assuming these engines have a sensor and/or regulator per side. I don't know for sure if he has double checked the fuel pressure sensor or not. - But he knows much more about engines than me so I assume he has done all that.

Any ideas appreciated.

Thank you!

 

Lots of us do not get involved with major modifications like this one. However, I think you need a new ECM.

 

If you’re still needing an answer….

I would hold off on replacing the ECM until you verify the harness is in tact. You have codes for open circuits on the FPR solenoid (mounted directly on the high pressure fuel pump) and injectors. The inability to control fuel pressure, combined with open injector circuits, points to wiring harness and pin fitment issues.

It’s not difficult to pinch the harness when reinstalling the intake. Additionally the pins on these components are easily bent if the connector isn’t square as it’s being installed.

I would remove the intake for a thorough visual inspection of the wiring harness and verify all the pins on the components are straight.

There’s also part of the harness that’s known to chafe on the frame/strut tower near the ECM, so check that as well.