Gen IV LS Swap E38 ECM P2122 and P2138 DTC - limp mode

[kcarruth25]

Good morning, I have searched through several posts before doing mine own for help, but nothing has been successful so far. We have a Gen IV 5.3 LS Swap into a 70 C10. Sometimes it takes multiple cycles of the key for the truck to crank, other times it will fire right up. But 99% of the time we have no pedal. Sometimes the codes will pop up as soon as you crank the truck, sometimes you press the pedal and get little to no response and the code will throw. Or sometimes you can mash the pedal slowly a few times before the code will throw. We purchased the harness, ecm, and pedal directly from PSI all together. It does have a Summit Racing Max EFI LS intake (Part # SUM-226122B-G2) installed but running a factory throttle body. Part # for TB is RME87. We are at a lost. We have received pinouts and diagrams to check all the wiring from PSI, and that has all checked out. I have attached a couple of data logs that the truck is doing when it loses pedal. We have not been able to drive the truck at all so the data logs are with the truck in park and trying to get the truck to respond to the pedal. Any help is greatly appreciated. Been working on this for over a month now. I have done nothing to the tune so far because I have no throttle response. I have attached the tune that in the ECM when we received from PSI. 25-07-01 11-13-09.hpl25-07-01 11-14-31.hpl25-07-01 11-17-18.hplFlips Truck As Found 6.20.2025.hpt

[Alvin]

It appears like lots of changes have been made to the airflow, electronic throttle tab. If you have a stock file for this we can know for sure.

Changes to this tab will cause odd issues like this.

I've also had similar issues on swap cars where interior screws shorted out the harness but still checked while ohming stuff out. I've also had one guy clamp his intake tubing to his throttle body so hard it caused things like this.

[kcarruth25]

Thank you, Alvin! Do you think PSI would have made those changes due to calibrating the ECM for the pedal we purchased from them? If I were to get a stock file, I would need one that is compatible with the pedal they sold me, correct? This is the only file I have for this ECM in particular, I read it straight from the ECM when we got it out of the box from PSI.

I will also say that we have noticed an issue with the battery draining on this truck. We put a brand new battery in it, I went to crank it this morning and literally nothing. Had to use a jump box to start.

[Alvin]

It's impossible to tell. You can try to find a stock file with the same OSID on the repository.

PSI is a good company but we are all human and there can be a mistake made. I'd probably check against the service manual on the pinouts.

[kcarruth25]

Thank you! I will search now to see if I can find one with the same OS. PSI is a great company, I have purchased multiple harnesses in the past, no issues at all. This is a first for me with this. PSI did provide us the correct pinout and we have checked that.

[Alvin]

I just wouldn't take nothing for granted. The service manual should be right.

[kcarruth25]

I will refer to the service manual. Good point. Are you referring to the service manual for the pedal type?

[kcarruth25]

Hey Alvin! I was able to find a stock tune in the repository with the same OS. I have attached it and the tune that is in the vehicle. Do you think the differences in the electronic throttle table are big enough differences to be causing this issue? I am not familiar with the electronic throttle tables at all. 1318519417.hptFlips Truck As Found 6.20.2025.hpt

[Alvin]

Those are not quite the same files so it's hard to know for sure. If you look the engine operating id and system id are different. The main OS is the same. Did you find any others that were closer to that?

If you using alldata for the diag. Use the vin out of the tune file to select the vehicle.

[kcarruth25]

I will go dig and see if I can find another one.

Just so I can wrap my head around matching calibrations, how do I know that the OS system in the ECM is compatible with the pedal and TB I'm using? I know PSI sold me the ECM and pedal together, but I just want to learn how I know it is all compatible?

[kcarruth25]

Swapped the TB with one off a running driving vehicle, same issue, so at least I have ruled out the TB.

[kcarruth25]

Good morning! After working with Gary at PSI yesterday, we discovered the pedal I received in my order was bad. We had a pedal on the shelf, plugged it in, and no more dead pedal. However, it's now not taking fuel. Solve one problem, and now a new one. You hit the throttle and it is falling flat on its face. It acts as if it will not take fuel at all. TB is actuating with the pedal now. Anyone have any suggestions where to start looking? Completely stock engine w/ aftermarket intake but stock TB. Stock injectors.

[gtstorey]

Good morning! After working with Gary at PSI yesterday, we discovered the pedal I received in my order was bad. We had a pedal on the shelf, plugged it in, and no more dead pedal. However, it's now not taking fuel. Solve one problem, and now a new one. You hit the throttle and it is falling flat on its face. It acts as if it will not take fuel at all. TB is actuating with the pedal now. Anyone have any suggestions where to start looking? Completely stock engine w/ aftermarket intake but stock TB. Stock injectors.

Not sure that "stock" injectors mean much in this case. Stock to what? You should always give part number for injectors to remove doubt about what you have.