Officially reaching out for community assistance

[El Es Roy]

I was ok up until now with searching trial and error configuring things and playing with options within my tune, it's all reversible when something is enabled that shouldn't be and vice versa. Now I've run into a legitimate driveability issue and I didn't even change anything when the problem presented.

Ill post my tune and log file for help 7.22.2021.hpl roy 7.hpt

I installed a vintage air Sanden compressor, had lines fabed, installed all other a/c components, charged system a/c working well. PSI harness was ordered with a/c integration option but I haven't hooked it into the system yet. Before I could look into how to do that this condition arose.

The truck starts cold (90 - 102 degree days) idles for a minute veh temp under the threshold for open-loop idle suddenly comes up to 750-1200 varies every time. Drive away the veh seems lacking in power and cuts out (like a fuel pressure drop) then intermittently cuts off randomly like and ignition failure sometimes poping (building up fuel with no ignition then igniting when it returns). Then as if something has changed it smooths right out and runs fine. I can find nothing loose or leaking or otherwise suspect of causing any of this. IAT seems high and it is drawing from air under the hood but I haven't changed anything. Added a/c components yet which would cause more heat but it's doing it from a cold start without running the a/c at all. Could a faulty IAC sensor giving an inaccurate value to the PCM cause this much havoc? Why does the power seem so down too? Expected some loss with a/c on but again nothings changed with a/c off so WTF?

Hope I havent asked anything stupid or used any incorrect terms, I am new to all this and I will get there so thanks for the patience. Its hot and frustrating and im trying but someone please help me see what im missing. Hate asking and dont rely on charity but despiration brings out the humble.

[5FDP]

Are you able to watch fuel pressure? I'd want to make sure it stays steady around 58psi.


This things has to be a dog, there is no timing in it for making power and you have a knock problem. Every time you get into the throttle enough it pulls the maximum allowed timing set in the tune, which is 4 degrees. So either there is a major issue with knock or you have a pending or current knock sensor code that is constantly pulling timing on you.

There is also the IAT and ECT pulling timing. The ECT doesn't need to pull timing until well over 210-215 degrees. My truck runs at 210 all day everyday without issue. Even though it's a newer truck than your engine the coolant temps of 195-210 doesn't require a timing pull. IAT temps above 120 are pretty high though.

There is no VSS working in that log either. If the stock transmission isn't being used anymore you should really disable the abuse mode on the engine side so it can't pull power away. Set it to 7,000rpm and 0mph.

[El Es Roy]

Dog isn't the word for it. It wont leave the driveway. Yes 700r4 is in it. the VSS is in the transfer case and has never shown any signal since i installed the PSI harness. Its a 2 wire pigtail that had to be extended (colors that PSI use aren't the same as GM so 50/50 chance right?) wasn't sure if the wires were polarity sensitive or not. Switching them enable the VSS again? Its just been too far down on the list to tend to just yet but i will if that will fix the problem. Thought maybe the 89 sensor in the case just wasn't compatible with the 01 LS PCM. I've noticed the IAT being so high. Looked through old logs and saw nothing over 92 degrees. This all started with the addition of A/C compressor and condenser back to the truck. WAIT NOW !!! Before you think the obvious, it does this without the A/C on at all and I have yet to introduce the A/C command signal into the PCM yet. It works completely independent of the engine management. So when its off and not creating any additional heat, nothings changed. That said, it did work fine for a week or so after A/C install then suddenly no power, idles fine. looked at scanner noticed the TPS stuck at 14.5% in one log then before I could begin to explore that it had gone to 0%. Figured it was just a failing TPS sensor so tested it, cheap enough.....replaced it even though it tested good. Replaced IAC, MAF and nothing changed. I did not see the knock issue or would've looked that direction. Didn't see a code for bad sensor. Would it give a bad code for a faulty knock sensor or just indicate knock when there isn't any?

This is all so new to me please forgive me. I hate being the dork that doesn't know his ass from.........but ill try to GET IT as quickly as I can. I so appreciate the community time and effort. Im not looking for high horsepower or anything radical, just want the wife to be able to go to Home Depot for yard supplies when she wants to without having to worry.

So shy of it being a knock sensor failing I should be able to go back and re-flash a tune that worked prior and it should run and drive, if its something Ive changed that I shouldnt have, in theory, correct?

Also in the DTC section of the tune, the OS includes many options that may not pertain to EVERY vehicle and every engine/trans configuration, thats why they are selectable. Im confused about 1 aspect of this process however. Does disabling something just turn off a system ie: Knock sensor data or the systems need for detecting knock detection at all? Or lets say i turn off anything TAC related because I have a cable actuated throttle body. If i miss something that is TAC dependent leaving it enabled, does that "turn on" the DBW system and clash with the things that make the DBC setup work properly? I'm just afraid I've failed to understand what something is or does enabled or disabled and its causing issues. I guess i could've worded it like this, In the DTC section does selecting something make it work or just keep the computer from seeing it?

I've never felt more NOOB in my life. Im sorry to waste anyone's time with this shit. Really. I would if I could , find someone to physically come here in person to look this over and pay them for their time and services, but I cant. Towing to a shop might work if I even knew where. Nothing in my area that I know of or have ever seen. I've been in the automotive arena all my shade tree life and know quite a few people, but no one knows a good "LS tuning" shop, that isn't so specialized that only the rich and famous can get in. I live in Sacramento CA. Good if your a politician but sad when it comes to motorsports. Sac Raceway has become a shadow of its former self. NHRA doesnt even bother sending the big names out here anymore. Any suggestions would be greatly appreciated as to who and or where i could take it.

BTW the fuel pressure is 58 - 62 consistently at idle or TRYING to accelerate.

Thanks for your time.

[kevin87turbot]

Dog isn't the word for it. It wont leave the driveway. Yes 700r4 is in it. the VSS is in the transfer case and has never shown any signal since i installed the PSI harness. Its a 2 wire pigtail that had to be extended (colors that PSI use aren't the same as GM so 50/50 chance right?) wasn't sure if the wires were polarity sensitive or not. Switching them enable the VSS again? Its just been too far down on the list to tend to just yet but i will if that will fix the problem. Thought maybe the 89 sensor in the case just wasn't compatible with the 01 LS PCM. I've noticed the IAT being so high. Looked through old logs and saw nothing over 92 degrees. This all started with the addition of A/C compressor and condenser back to the truck. WAIT NOW !!! Before you think the obvious, it does this without the A/C on at all and I have yet to introduce the A/C command signal into the PCM yet. It works completely independent of the engine management. So when its off and not creating any additional heat, nothings changed. That said, it did work fine for a week or so after A/C install then suddenly no power, idles fine. looked at scanner noticed the TPS stuck at 14.5% in one log then before I could begin to explore that it had gone to 0%. Figured it was just a failing TPS sensor so tested it, cheap enough.....replaced it even though it tested good. Replaced IAC, MAF and nothing changed. I did not see the knock issue or would've looked that direction. Didn't see a code for bad sensor. Would it give a bad code for a faulty knock sensor or just indicate knock when there isn't any? If it was a faulty or disconnected knock sensor, it usually gives a code...but not always.

This is all so new to me please forgive me. I hate being the dork that doesn't know his ass from.........but ill try to GET IT as quickly as I can. I so appreciate the community time and effort. Im not looking for high horsepower or anything radical, just want the wife to be able to go to Home Depot for yard supplies when she wants to without having to worry.

So shy of it being a knock sensor failing I should be able to go back and re-flash a tune that worked prior and it should run and drive, if its something Ive changed that I shouldnt have, in theory, correct?

Also in the DTC section of the tune, the OS includes many options that may not pertain to EVERY vehicle and every engine/trans configuration, thats why they are selectable. Im confused about 1 aspect of this process however. Does disabling something just turn off a system ie: Knock sensor data or the systems need for detecting knock detection at all? Or lets say i turn off anything TAC related because I have a cable actuated throttle body. If i miss something that is TAC dependent leaving it enabled, does that "turn on" the DBW system and clash with the things that make the DBC setup work properly? I'm just afraid I've failed to understand what something is or does enabled or disabled and its causing issues. I guess i could've worded it like this, In the DTC section does selecting something make it work or just keep the computer from seeing it?
You shouldn't turn on any of the DTC's on yours unless the factory had them turned on.
If you do turn them on, it may or may not cause an issue. There's no good reason to do so.
You can set the three knock sensor codes to "No Error Reported" and they will still function.
The DBW can only be enabled or disabled in the System Options table.

I've never felt more NOOB in my life. Im sorry to waste anyone's time with this shit. Really. I would if I could , find someone to physically come here in person to look this over and pay them for their time and services, but I cant. Towing to a shop might work if I even knew where. Nothing in my area that I know of or have ever seen. I've been in the automotive arena all my shade tree life and know quite a few people, but no one knows a good "LS tuning" shop, that isn't so specialized that only the rich and famous can get in. I live in Sacramento CA. Good if your a politician but sad when it comes to motorsports. Sac Raceway has become a shadow of its former self. NHRA doesnt even bother sending the big names out here anymore. Any suggestions would be greatly appreciated as to who and or where i could take it.

BTW the fuel pressure is 58 - 62 consistently at idle or TRYING to accelerate.

Thanks for your time.

I would recommend reading 5FDP's advice just above. He have you some real gold nuggets...especially about disabling the Abuse Mode.

[village_idiot]

Adding to the above, your log shows a P1122 DTC for intermittent TPS low voltage. This could be giving you issues as well

[El Es Roy]

Thanks all (esp. 5FDP) I took your advice and adjusted things accordingly. Out of desperation I also segment copy and pasted EVERY SINGLE table of a stock 6.0 GM Truck file into my licensed copy and what do you know, she runs. Took some time (like hours) but worth it. One thing still troubles me. The TPS % in scanner still reads "0". How is that possible? Is my PID configuration incorrect? Did I not add the channel to monitor TPS correctly? Didn't save it after adding it, or cycle the ignition at some point or some other procedure I'm failing to follow that's not allowing it to monitor? All I can think of........

One last thing.....Where did you find this P1122 that triggered? I haven't seen any codes (except for the ones I expect because of my current status of things like A/C and Cruise) I tried looking for triggered DTC's in a log file and the option in scanner isnt selectable offline. Im sure its my lack of understanding of the program but ....learn me how. PLEASE!

[tune2mbt]

One last thing.....Where did you find this P1122 that triggered?

Open the log, click details on the bottom left. You will see the codes there.

[blindsquirrel]

In general, do not use the generic SAE channels in your log. Use the non-generic GM-specific ones, especially for throttle stuff.

[blindsquirrel]

Another thing, 0% is very unlikely to mean 0 volts. If the channel exists (it should), you can log actual raw TPS volts in addition to the interpreted % value.

[El Es Roy]

OK so, Ive been BUSY and the trucks been sitting with the front diff howling and grinding (even though its not in 4wd) and axles and drive line removed, I can once again drive the thing. Ive logged a couple of trips and still its never run better despite the absence of TPS signal. Again Ive confirmed continuity of the 3 wires from TPS sensor to PCM. 3 wires all have perspective values, 4.8 volts......solid ground.......sweeps between .06 volts to 4.7 volts (as i remember them) as throttle is depressed.

I did however discover that in the DTC section of the tune I had everything labeled "Throttle/Pedal...." unchecked and set to not report. What is the reason for the DTC's needing to be enabled that say "Throttle/Pedal......." when its DBC? Aren't those the ones pertaining to DBW hardware? Shouldnt I leave them disabled?

Ill include a copy of the latest logs and tune in case anyone has any questions.

[blindsquirrel]

Abuse mode is still enabled. Brake torque management still enabled, I would think that's something you would want turned off. I stopped looking at that point.

Was this originally a DBW PCM/tune that you converted? What was the donor vehicle, what is the current vehicle, which of the original parts/systems have been retained and which have been deleted? Without the full knowledge of what's been changed and what's there now it's impossible for anybody to say which DTCs should be kept and which should be turned off.

You still have an inop TPS - it only very occasionally reads anything other than zero in the latest log. It is a waste of time and brain power to worry about anything else until that is working. You cannot fix or identify an intermittent by checking the voltages once and deciding there's nothing wrong.

[kevin87turbot]

You have a few problems that need to be resolved, just as BlindSquirrel indicated...

1. Disable the engine Abuse Mode. It's been mentioned multiple times now.

2. The TPS is only working sporadically. It could be a faulty TPS or a bad connection.

3. The TPS related DTC's need to be stock. They are there to help you determine the problems that need to be fixed.

I've attached a stock 2001 DBC calibration. You can use it to determine which DTC's have been altered.

2001gmcsierra53Lorangestock.hpt

[El Es Roy]

I would like to thank both blindsuirrel and kevin87turbot, as well as everyone else that belongs to this community for their dedication and time to help guide those of us just learning all this. Its very overwelming at times with ALOT of info coming at you from many diff directions. Ive taken this in another direction out of frustration. Perhaps you can tell me if i am headed in the right direction.

1. Replaced the PCM with one from PSI. Its loaded with all the options my PSI harness was built with (A/C, cruise cont., manual trans. etc.) DTCs are preloaded (enabled and monitoring accordingly) and relitive to the correct year of the engine.

2. FINALLY traced down the intermitent TPS signal issue and repaired it. (simply a broken wire to the PCM. Every time I tested continuity in that wire I tested fine. (you know how that goes)

3. Trans options arent even loaded into this PCM so Abuse Mode control cant even be enabled. (I was listening when it was mentioned multiple times, I just never got past the TPS signal loss issue to address it)

The truck now idles correctly when cold as well as when warmed up. No longer dies when it returns from any misc. engine speed when letting off the throttle hard.

I've secured a spot to get some dyno time in, in the near future so fine-tuning will smooth out the rough edges when that's complete. I will attach my new tune and a short data log file a bit later (its in my other laptop), maybe see what the help from others can lead to. Posting that tune to compare to both my old tune and my new one helped my understanding of things as well as confirm I was on the right path. Thanks again.

Thank you all again.

[El Es Roy]

Here they are. Thannks again.12212156 PSIRoysNewComputer9.20.2021.hpt9.22.2021newinjectors.newcomputer.newplugsnwiresidle.hpl