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

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. Attachment 161928Attachment 161929Attachment 161930Attachment 161931

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.

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.

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.

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.

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

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

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. Attachment 161971Attachment 161972

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.

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?

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

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.

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Originally Posted by 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.

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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.

I had P2138 on my setup when I first put it together, too. But it was my own wiring, not PSI.

Add channels for pedal position D & E in your log, and chart them. They are under Engine -> Accelerator and Throttle -> Accelerator Pedal.

With mine, when I pressed the pedal, I would get one peak and one valley; they should both peak when you press the pedal. If they don't go the same way then they don't "correlate", hence the DTC.

If one is inverted, you can swap the wiring at the pedal to reverse it - but you have to be careful selecting the right pair to swap. What pedal are you using?

Some of the GM pedal throttle voltages go in the same direction some go in different directions. Depends on which ECM you are using. This is why it’s always iffy to mix the three from different applications.

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Originally Posted by DanN

I had P2138 on my setup when I first put it together, too. But it was my own wiring, not PSI.

Add channels for pedal position D & E in your log, and chart them. They are under Engine -> Accelerator and Throttle -> Accelerator Pedal.

With mine, when I pressed the pedal, I would get one peak and one valley; they should both peak when you press the pedal. If they don't go the same way then they don't "correlate", hence the DTC.

If one is inverted, you can swap the wiring at the pedal to reverse it - but you have to be careful selecting the right pair to swap. What pedal are you using?

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Thank you for all of this!

After hours of troubleshooting with PSI, we did discover that the brand new pedal was bad right out of the box. Plugged in a different pedal, no more codes, no more dead pedal. Now we are trying to figure out why it will not take fuel. Press the pedal and it won?t take fuel. Wants to die and fall on its face.

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Originally Posted by gtstorey

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.

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After talking with the customer, they are Amazon injectors. Anyone had any good luck with these or do you think its the culprit? Injectors he bought and installed are MACAX 12580681 off Amazon. We always use AC Delco so asking if anyone has experience with these and think they could be the problem.

The odds of getting good injectors on Amazon are probably less than 50-50. It would not surprise me if it’s not more like 10% good.

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Originally Posted by gtstorey

The odds of getting good injectors on Amazon are probably less than 50-50. It would not surprise me if it?s not more like 10% good.

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Also just did some research and it appears the injectors are 30 lb/hr injectors but the exam is tuned for 50ln/hr injectors per the invoice from PSI. Couldn?t this be why it has no throttle response and why it tries to die when pressing the pedal? Smaller injector can?t fuel the way the ECM is commanding it to right?

All of the injector needs to be right, not just the flow rate. But I would be surprised if you can get any real data for them. Advertised flow rate probably isn’t right either. I just don’t expect investors that cost less than $10 each to be worth anything.