[Chrome383Z]

Still trying to figure out this code. I run the car and it does fine sometimes on the first start, but throws this code after I turn it off and back on or after a lot off idle/low throttle and is a short to voltage. There is a member that had the same issue and went back to stock (LT1 HPFP) and the problem was resolved.

I don't know what to do. I reached out to LPE and their feedback was it couldn't be the pump... my only option is to pull the blower off and throw the LT1 stock pump back on to prove that wrong... which is a ton of work but i'll do it. Any ideas? The HPFP wires go directly to the ECM, i don't know what could be causing this.

[Chrome383Z]

Played around a bit today, unplugged the JMS booster pedal adapter and removed everything from the OBD2 connector just trying to eliminate things that have changed. Didn’t help anything. Verified voltage out of JMS was fine. It only throws it after the car is hot and a lot of idling/low throttle. Typically after I shut it down and restart.

Here’s a log with the exact spot (Verticle line) it goes into limp mode. I logged the HPFP angle, is the on/off at idle normal? It stopped doing the on/off and went into limp mode shortly after. This has been a repeat symptom when I can get it to log a fault at idle.

[Chrome383Z]

Next steps are to run through the DTC circuit testing GM has listed for this code where I verify with a test lamp the control circuits turn a test lamp (to ground) on/off on the fuel pump wires when I command the regulator on/off. Not sure if I can do this with hptuners, may need a tech II. What baffles me is the wiring was fine prior to the blower install when I was full bolt on. Harness is fine. Only thing that changed in the HPFP circuit was the LPE big bore pump and a 2016-2018 injector harness as they changed the LT1 fuel pump connector in 2019. Seems I bought a bastard year. lol. I’ve checked the connectors 10x already looks fine even cut the tape back on the wire to the fuel pump and there’s no issue with the wires that I can see.

[cjperformance]

Sorry, I don't have any input, but im following along. Interested in the outcome when you find it. Its great when folks share this kind of info with logs amd other info. Great for learning! Didnt want you to get lonely with no other feedback

[Chrome383Z]

I think I have this resolved. I turned off the HPFP noise control. All of this was enabled, and I saw on some ZL1 tunes that it was turned off. What's weird is the ZL1 tune file had different options and mine don't make sense. The first picture is my 2019 stock, 2nd with everything disabled (my change), the third is the ZL1 which has more options. ZL1 had low current enabled, but I just disabled it all. I had to zero out pump disable rpm as there was no option to disable.

I'm wondering if the HPFP in the 2019+ LT1 cars had a change in the coils/diodes and the older LT4/LT1 (LPE HPFP) can't handle the voltage spikes that can be created with the pump pulsing like it does with this noise control turned on.

Completed a 45min drive yesterday and shut down multiple times without any code. So for now at least I think this was the culprit. Now it's possible I'm Band-Aiding a bad pump - but if the pump noise has increased I sure don't hear it over the headers/blower, and if it fixes the problem ok with me. Something 2019+ folks should at least look at if they have a LT4/LPE HPFP (older LT1).

I'll report back in a few weeks to see if it is still performing well. Thanks!

[WiggyB]

This is the same code I have been getting. I'm going to share this with my tuner.

[Joshinator99]

Nice work Chrome! Always good to know this stuff as you never know who it will happen to next!

[Chrome383Z]

Well back to square one, it helped for a short time but now throwing the code again. I’m at a loss…. What would prevent a short to voltage after a tune download then after a set amount of time throw it again. Doesn’t make sense to me…. Fuel pump maintains pressure requested at all times. Surely I’m not the only person with a 2019+ with a LPE or LT4 pump having this issue. ����*��

[KingLT1]

Does this particular code give you the option to set to "do not report"? That's what I would do if the fuel pressure looks fine.

[Chrome383Z]

Originally Posted by KingLT1

Does this particular code give you the option to set to "do not report"? That's what I would do if the fuel pressure looks fine.

Haven’t tried that yet. Setting in HP Tuners? Can set to no error reported but might still throw a code. Worth a shot.

[Chrome383Z]

Fuel pressure is fine. Always on point.

[KingLT1]

Originally Posted by Chrome383Z

Haven’t tried that yet. Setting in HP Tuners? Can set to no error reported but might still throw a code. Worth a shot.

Yes under Engine/diag. If you set it to "do not report" it will not report the code. I wonder if it's the adapter harness for the pump 2019+ requires because I see a few threads about it with a quick search.

Didn't you have Ted Jenetty tune it? I seen him post that he could fix the issue for another member in this thread? https://www.camaro6.com/forums/showthread.php?t=592766

The problem is nobody shares information or follows up with a fix to their issue on forums anymore and it's annoying as hell.

[Chrome383Z]

Originally Posted by KingLT1

Yes under Engine/diag. If you set it to "do not report" it will not report the code. I wonder if it's the adapter harness for the pump 2019+ requires because I see a few threads about it with a quick search.

Didn't you have Ted Jenetty tune it? I seen him post that he could fix the issue for another member in this thread? https://www.camaro6.com/forums/showthread.php?t=592766

The problem is nobody shares information or follows up with a fix to their issue on forums anymore and it's annoying as hell.

Yeah I might reach out to Ted again. He thought it might be the pump and directed me to Lingenfelter. Lingenfelter said it couldn’t be the pump. I actually replaced the wire harness with another new one two weeks ago just throwing parts at it. Didn’t help. It’s a weird one for sure. I’ll go over the main harness again and look for fraying but didn’t have this issue full bolt on, so I’m 99% sure it’s not the harness.

Thinking ECM, something in tune, maybe pump. May turn the JMS back more but this circuit is all in the ECM, doesn’t go back to CCM so really don’t think it’s that. And it does it at low RPM never high when JMS would be active anyways. It’s a conundrum. I’ll try turning to no error reported, just don’t think that prevents the car from going into reduced engine power mode. From what I’ve read….

Few people have had this problem, one it was the harness, another a connector behind drivers side wheel which makes no sense (different circuit), another went back to stock LT1 pump. Two never posted again so no clue how or if they fixed it. I PMd but no answer. lol. I’ll figure it out one day. Or get pissed off, sell the LPE pump FIC injectors and throw the LT1 pump/injectors back on and go port inj.

[Kerry]

Make double sure u have the jms hoked up to the correct wire. I had to go under the car and hook up direct their. Just a thought