LT1 Swap > 2015 Sierra > Cranking No Start / 0 psi on Rail, 72 psi elsewhere

[lippmoney]

so, confession time - the fuel system up until today had an 8AN line directly feeding the hpfp. I have a check valve back between the abs module and the front edge of the tank but it wasnt cutting it. i re-installed the factory line extension + check valve assembly and while things are better, and i had a start / catch / im still not calling it run / stall scenario and was able to grab some data that i'm hoping one of you can help me sort out.

see attached.

06252023.hpl

[GHuggins]

Just a few things - I don't see any hpfp rail pressure in the log being displayed. I also see absolutely no airflow going into the engine - no air = no fuel. Dynamic also shows very little air (.74 g/s at 1100 rpms). Air calc mode is high speed = MAF. You sure all of the connectors are hooked up in the fuse block and everywhere else? F43 and ignition relay is good and working? Have you tried failing the MAF and seeing if it'll run then?

[lippmoney]

sensor audit last night - here's the summary along with screenshots of sensors being described so that we are all speaking the same language - more for me not you guys. If a sensor is not listed below - it has a home / lives or there is no issue / no question from my end:

1. Engine Oil Pressure Control Solenoid Valve: this connector has no sensor to plug into. My engine builder used an LME Billet front cover and did VVT delete with hardware. This point of connection doesnt live any more. The wires and connector are zip tied back and out of the way of the serp belt. Not sure if this is an issue from programming standpoint.

2. Any and all AC System Sensors (two of them i believe): two connectors with no sensors to plug in to. i have ordered an entire new AC system as the old one was shot when the original motor committed suicide. These are zip tied out of the way under the motor until later this week when the AC system goes in. I'm assuming this is a non-issue.

3. Fuel Tank Pressure Sensor: connector with no sensor to plug in to. Aeromotive fuel hat has no provisions for this sensor. In discussion with Carl @ Vaporworx it was determined that this sensor could "go away" along with the balance of the evap system (my choosing) as there were issues with the previous owner and his lack of ability to fuel the factory gas tank efficiently. I dont exactly know what the issue was - but he weas getting backpressure and the pumps would click off a bunch apparently). Fuel level sending unit reports correctly off the float in the tank, Not sure if this is an issue but i doubt it.

4. Evap Purge: purge valve is hooked up, but is not installed in the charger or plenum. i believe whipple may have sent the wrong kit out. There is no place for this sensor to land per the instructions. I had a change of plans with my build was going to do a replacement 5.3 but changed it to 6.2, called them and they acknowledged the change but this one is plugged in and tied off to the firewall. I'm running a catch can for my pcv/evap/manifold oil capture issues.

5. MAP: replaced by LT4 TMAP which now lives at back side of whipple. Breakout harness and additional sensor should be arriving today for Baro, but i don't think that's the main issue here.

other than that - i've done all the usual checks:

HPFP is plugged in, i measured for the lash - it was fine
the injector bank harnesses have been verified
plugs are brand new from whipple, gapped properly
new plug wires all fully seated
brand new coils (GM/ACD flat style)
air shouldn't be an issue - brand new MAF
new harness from whipple to maf and splitter - verified its plugged in the right orientation

I have not been able to run any sort of throttle body learn (i am running am lt1/lt4 tbody), crank learn, any learning mode as i cant get the thing running long enough to reset anything. to my untrained self, i feel like this might be a part of the problem but i know very little about these motors although that is changing by the hour.

Live data scroll through on the autel (it's what im used to) shows a few items of interest - namely the "high pressure fuel system malfunction" which is news to me since i dont have a corresponding code. also of note is the abnormally high pressure reading on sensor 2. i know these all point to electrical - i get it, but im looking for some guidance or ideally someone who encountered a similar issue. while i'm not afraid to visually inspect yards of wire for an insulation tear, the more i say it the less appetizing it sounds. here's the live data - pause if you see something weird:

https://youtu.be/eM0LywOxp2M

again - thank you all for dealing with my noob to gen 5 self. this one was not planned - came as an emergency and i'm suffering the consequences of an unplanned swap in order to get back on the road as quickly and pain free as possible. mission unaccomplished haha...

ryan

VVT Sensor.pngevap solenoid.pngftp and ac.pngevap purge.pngmap.png

[GHuggins]

It needs to see airflow to apply fuel. I also seem to recall something about the ac pressure switch needing to be plugged in even if it's only hanging there. Don't remember on the oil pressure control solenoid, but might be important. Make sure the MAF is installed correctly and possibly even try MAF failed.

[lippmoney]

Greg - read a few of your older posts about direct wiring in the whipple harnesses, so tackled that and checked it off the list, then dove into airflow. Intake off to get visual on the tbody blade while commanding different throttle positions. found the problem for this particular issue

https://youtu.be/lZTAyaRLgBA

Now what? Was reading about messing with the torque tables but need more direction before I go screwing around with any of that.

Maf verified when I did the harness splice. Good to go there. Was going to do a memory drain with the battery cables but wanted to avoid any ancillary issues that may cause and check in here first before I do. Next up is maf fail.

Thanks - progress it feels like

[GHuggins]

If the TB indeed isn't working that could be your fuel shutdown issue too - it does a self test with key on and if that fails. If you have anyone around, have them work the pedal while watching the TB and then you can also have a meter T'ed in and watch voltages at the same time. Scanner controls aren't always the best to test with, but that one did look very "jerky to glitchy".

[lippmoney]

a few things on the agenda for tomorrow:

1.TB Self Test / Ice Break Mode resolution: did a little digging in alldata to see what i could see. turns out that its going in to "icebreak mode" which i didnt know was a real thing until tonight. See alldata writeup of the Throttle Actuator Control attached. i need to keep digging on this as to why its doing this. *edit - im 99% sure this is the reason, the pdf has a lengthy description of the various REP modes and why...
2. TB extension harness break down and splice: will strip this and splice in like MAF. i did a wiggle test on the tbody and sure enough when i grabbed the harness extension at the tbody actuator connector, as soon as i touched the connector the tbody cracked open a little.
3. MAF Fail and log (hopefully - need to do this for diagnostic purposes at a minimum).

one item of note:

- upon examination of the tbody harness extension from whipple i noticed 6 wires, end to end. the engine harness side only has 5 wires, in agreement with Alldata wiring schematics. at the opposite end, on the tbody actuator there are 6 pins which would contradict the wiring schematics from alldata...

mid post interruption: pulled the pinout for the TAC, pin 6 is unused, pinout attached. too lazy to edit the post to make sense, posting this here in case a future swapper ponders the meaning of life like i am at midnight thinking about throttle bodies and fuel cut off issues...

TAC.pdftbody wiring.pngtbody pinout.pdf

[lippmoney]

updates to the post last night:

1.TB Self Test / Ice Break Mode: still sorting this out but i am no longer encountering ice / break dance mode. The TB is silent on KOER as opposed to the high speed clacking it used to do. Suspect there are still lingering issues however, application of the gas pedal = no movement on TB. This was accomplished by the next item...

2. TB extension harness break down and splice: i have almost completely eliminated the throttle body wiring harness extension as provided by whipple. i believe the issue is in the pin connections made - being loose or sloppy in how they are individually locked down (i.e. they aren't). I took some pictures and once i confirm this is the issue i'll be forwarding to whipple as a heads up. Interestingly enough the harness is labeled as made and qc'ed in USA and is not a generic commodity or purchased part - they may actually make these in house.

2b. O-Scope Reading of TB at rest/KOER: within the next 30-45min. Will post up data stream.

3. MAF Fail and Log: pending some other harness related cleanup i'm doing - specifically an alternator 2pin connector i'm waiting to have delivered, then i'll hit the MAF Fail and hopefully ignition.

Following up on a few open items from the past few days:

this one is obnoxiously absent from internet searches and seems so simple probably because we are a full generation of motors deep with VVT / DOD and its old news at this point:

Unused VVT and DOD delete Electrical Connectors: Program the features out in HPT, turn off whatever related MIL lights come from those sensors (i dont have the numbers handy - but there are posts here that deal with it) and secure the wires back onto the harness. Done.

AC Connectors / impact on startup: not sure still - needed to order some new connectors (2 at the compressor got mangled - bare copper at the throat of the connector), i'll slap them on when they get here.

[GHuggins]

So it was seeing too high of an amp draw from junk crimps in the whipple harness then? Causing it to go into this "ice break REP mode"? Interesting...

[lippmoney]

So it was seeing too high of an amp draw from junk crimps in the whipple harness then? Causing it to go into this "ice break REP mode"? Interesting...

that's my working theory at the moment - could end up being something else. Heading back out now...

**Edit: its something else. i've got a "TAC disabled" readout on a PID on the Autel. More investigating...

[GHuggins]

Make sure you didn't cause it unplugging stuff - these will continue running self checks even after key off for a lot of things, so may need to clear codes then re-evaluate it.

[lippmoney]

10-4

at this point, there are a few consistent thorn in my side codes that keep rearing their ugly little heads after code diagnostics / clears / etc. i've sorted out which circuits they pertain to and just need to do some old fashioned physical tracing wire by wire until i find the breaks in the insulation and repair them. This is a lesson learned for future swappers - sometimes its worth considering buying a brand new factory harness (~$500 in my case for a complete 2015 Sierra 1500 engine harness from GM) especially if the existing harness has seen a lot of off-road use or other "heavy use" indicators. I realize many / most of you are road course go fast guys where this probably wont apply but for the off road truck guys this could be a huge time saver.

Example: nearly all of my coil connectors have broken insulation where the wires enter the connector - right at the stress point where the wire could bend. Just about every single one - broken insulation and copper exposed. On the injector harness its different - missing connector locks. Normally im the guy to laugh these things off as unimportant safety devices but in this application i'm finding these little details are everything and have been replacing sub-harnesses when i can or making new connector splices when i cant. Once I get this thing running and fully error free i think i'll be doing a harness swap for piece of mind sake.

Here are the codes i'm left with - a few new ones have come up that are interesting:

P0178 - Fuel Composition Sensor Low Freq (new one - i'm not a flex fuel truck and don't have the sensor)
P0192 - Fuel Rail Pressure Sensor Circuit Low Volt (consistent code - have replaced the sensor, still throwing code, likely short)
P0315 - Crank Position System Variation Not Learned (consistent code - cant clear until i can start the engine is my understanding)
P0532 - AC refrig pressure sensor low volt (consistent code - replacing AC system shortly - no big deal)
P0621 - Generator L-terminal (consistent code - repairing connector once i receive it)
P06A3 - 5V Ref 4 Circuit (new one - related to APP Sensor 1 and possibly TPS? inspected APP 1 connector and all looked ok but need to hook up and read the voltages on the pins)
P127C - Fuel Rail Pressure Sensor 2 low voltage (consistent code - related to 0192)
P06DA - Engine Oil Pressure control solenoid valve control circuit (consistent code - i believe a carry over code from VVT/DOD delete that needs to get turned off)

i'll be playing automotive electrician the next few days. if anyone hears violent screaming in Southern California - it's me. Scream back.

[lippmoney]

updates / questions:

P0178 - Fuel Composition Sensor Low Freq (new one - i'm not a flex fuel truck and don't have the sensor)
*Validated replacement connector and pigtail splice, cut out solderstick splice, replaced with crimped, marine grade h/s splice and overlayed with h/s tubing. Ran through diagnostics up to hooking up AWG and stopped.
**Next steps: will need to trace wiring from FF sensor harness up to ECM.
***QUESTION: my truck was not a "FlexFuel" optioned vehicle and did not have the associated sensor. My truck is reporting 40% ethanol content currently (score!) which leads me to believe there are obvious wiring issue yet to be discovered (2x score). How did GM address sniffing alcohol content on cars that never had the sensors installed? Did the ECM monitor some other PID's and figure it out?

P0192 - Fuel Rail Pressure Sensor Circuit Low Volt (consistent code - have replaced the sensor, still throwing code, likely short)
*pulled blower to access sensor cleanly / completely, front probed sensor connector and ran continuitty and ohm check from end to end (X2 and X3 connectors) every thing rang out and displayed .3 to .4ohm. Seems like wiring is not the issue. Possible CanBus / 5v ref system issue?
**Next steps: run prelim checks on balance of other codes to see if any scales of magnitude / elimination can plow through some of these

P0315 - Crank Position System Variation Not Learned (consistent code - cant clear until i can start the engine is my understanding)
*no action on this one - need truck running first

P0532 - AC refrig pressure sensor low volt (consistent code - replacing AC system shortly - no big deal)
*no action on this one

P0621 - Generator L-terminal (consistent code - repairing connector once i receive it)
*spliced in new connector - issue resolved

P06A3 - 5V Ref 4 Circuit (new one - related to APP Sensor 1 and possibly TPS? inspected APP 1 connector and all looked ok but need to hook up and read the voltages on the pins)
*no action on this one

P127C - Fuel Rail Pressure Sensor 2 low voltage (consistent code - related to 0192)
*pulled blower to access sensor cleanly / completely, front probed sensor connector and ran continuitty and ohm check from end to end (X2 and X3 connectors) every thing rang out and displayed .3 to .4ohm. Seems like wiring is not the issue. Possible CanBus / 5v ref system issue?
**Next steps: run prelim checks on balance of other codes to see if any scales of magnitude / elimination can plow through some of these

P06DA - Engine Oil Pressure control solenoid valve control circuit (consistent code - i believe a carry over code from VVT/DOD delete that needs to get turned off)
*double checked code - can be turned off, its a carry over from dod delete and is not applicable any more.


oh and failed out the MAF but guess what?? still didnt start. log attached. tune attached too - noticed that it never uploaded along with a few other files that i wanted to upload for y'alls discerning review.

[GHuggins]

updates / questions:

P0178 - Fuel Composition Sensor Low Freq (new one - i'm not a flex fuel truck and don't have the sensor)
*Validated replacement connector and pigtail splice, cut out solderstick splice, replaced with crimped, marine grade h/s splice and overlayed with h/s tubing. Ran through diagnostics up to hooking up AWG and stopped.
**Next steps: will need to trace wiring from FF sensor harness up to ECM.
***QUESTION: my truck was not a "FlexFuel" optioned vehicle and did not have the associated sensor. My truck is reporting 40% ethanol content currently (score!) which leads me to believe there are obvious wiring issue yet to be discovered (2x score). How did GM address sniffing alcohol content on cars that never had the sensors installed? Did the ECM monitor some other PID's and figure it out? This is how it's set up in the tune - change to disabled and it'll get rid of that code. You also need to set the dtc to no error for the sensor although once it's set to not have one it shouldn't run the test. 40% is the default for an open circuit or sensor fault once activated in the calibration.

P0192 - Fuel Rail Pressure Sensor Circuit Low Volt (consistent code - have replaced the sensor, still throwing code, likely short)
*pulled blower to access sensor cleanly / completely, front probed sensor connector and ran continuitty and ohm check from end to end (X2 and X3 connectors) every thing rang out and displayed .3 to .4ohm. Seems like wiring is not the issue. Possible CanBus / 5v ref system issue?
**Next steps: run prelim checks on balance of other codes to see if any scales of magnitude / elimination can plow through some of these Take a look at this youtube vid to make sure the correct connectors are hooked up. https://www.autocodes.com/p0192_2015...silverado.html

P0315 - Crank Position System Variation Not Learned (consistent code - cant clear until i can start the engine is my understanding)
*no action on this one - need truck running first

P0532 - AC refrig pressure sensor low volt (consistent code - replacing AC system shortly - no big deal)
*no action on this one

P0621 - Generator L-terminal (consistent code - repairing connector once i receive it)
*spliced in new connector - issue resolved

P06A3 - 5V Ref 4 Circuit (new one - related to APP Sensor 1 and possibly TPS? inspected APP 1 connector and all looked ok but need to hook up and read the voltages on the pins)
*no action on this one

P127C - Fuel Rail Pressure Sensor 2 low voltage (consistent code - related to 0192)
*pulled blower to access sensor cleanly / completely, front probed sensor connector and ran continuitty and ohm check from end to end (X2 and X3 connectors) every thing rang out and displayed .3 to .4ohm. Seems like wiring is not the issue. Possible CanBus / 5v ref system issue?
**Next steps: run prelim checks on balance of other codes to see if any scales of magnitude / elimination can plow through some of these

P06DA - Engine Oil Pressure control solenoid valve control circuit (consistent code - i believe a carry over code from VVT/DOD delete that needs to get turned off)
*double checked code - can be turned off, its a carry over from dod delete and is not applicable any more.

[lippmoney]

P0178 - excellent - thank you!! curious on the ability of the stock system still... with ethanol in all of the fuel in varying amounts (or changing at least) does GM have flexibility built into the tables or is there another means to test ethanol content that i'm unaware of?

P0192 - have seen this, have verified previously, will do so again in the morning just to make sure... stupider things have been done.

take a look at the edited post when / if you can - files uploaded that weren't there on your previous review... and i was able to (i think - Hz were flatlined) fail the MAF as you suggested.

progress... slowly but steadily... thank you for your help again Greg!

[lippmoney]

P0178 - engine > fuel > flex fuel > general > flex fuel: disabled - DONE
P0178 - engine diag > P0178 and P0179 > SES Enabled (left alone) > No Error Reported - DONE

[GHuggins]

P0178 - excellent - thank you!! curious on the ability of the stock system still... with ethanol in all of the fuel in varying amounts (or changing at least) does GM have flexibility built into the tables or is there another means to test ethanol content that i'm unaware of?

P0192 - have seen this, have verified previously, will do so again in the morning just to make sure... stupider things have been done.

take a look at the edited post when / if you can - files uploaded that weren't there on your previous review... and i was able to (i think - Hz were flatlined) fail the MAF as you suggested.

progress... slowly but steadily... thank you for your help again Greg!

Once you install a flex sensor, which all trucks should have the connector for, you just enable it in the tune and populate the necessary tables for it. This is probably the most common thing being done right now with fuel cost. If you tow with your truck it REALLY increases the low end torque too, so a nice benefit there as well.

Hoping it's just a simple connector mismatch like in the vid. Would explain everything too. Also wondering at this point with what you've described about the wiring if you aren't better off to get the new harness. Might save a lot of other headaches and connector purchases later

For the MAF fail, the rpms never got high enough to actually fail it, but either way it was actually reading airflow now so big progress there.

[lippmoney]

**edit- fixing the throttle body info, had to go back and look at what i ordered as it changed twice during the build... final answer is 95mm "lt1/lt4" tbody from Granatelli.

Once you install a flex sensor, which all trucks should have the connector for, you just enable it in the tune and populate the necessary tables for it. This is probably the most common thing being done right now with fuel cost. If you tow with your truck it REALLY increases the low end torque too, so a nice benefit there as well.

enabling ethanol / flex is on the list once this thing is road worthy. it was on in the tune as requested by me from the tune provider. so that all checks out.

Hoping it's just a simple connector mismatch like in the vid. Would explain everything too. Also wondering at this point with what you've described about the wiring if you aren't better off to get the new harness. Might save a lot of other headaches and connector purchases later

tell me about it - 4 of those coil connectors = about $80 from RA alone. ouch.

*lightbulb moment - i am running a 95mm lt4/lt1 TB not matched at all to the ECM obviously. Could this be the source of my issues? I know the sequence of events leading up to the L83 exiting the chat / world / universe and it never made sense to me that there weas a harness break that was related to or a side show in the main act of the motor throwing #8 rod through he side of the block. (pics attached for those who are curious). I cant simply toss the L83 tb on as the whipple throat is configured for big body TB and i need some adapter science to make the smaller L83 fit. I'm sure i could find the adapter online easily but i'd prefer to use the current unit especially since i have the TAC motor assembly from the L83 on this TB anyways and don't see why it wouldn't work. Let me know if i'm barking up the wrong tree in the wrong forest though.

For the MAF fail, the rpms never got high enough to actually fail it, but either way it was actually reading airflow now so big progress there.

^ this points to the TB even more - correct? i mean if air, if gas, spark has been confirmed... where's the boom? I also saw my friend "fuel cut unknown: 00 11 and 00 12" show up to the party....

[GHuggins]

Those fuel dtc's will shut it down even if it does fire. LT4 TB's are fine on the l83.

[lippmoney]

Verified correct harness orientation and side placement, reassembled, writing now, update shortly…