Maybe bit ott to big of the apple

[Xlexustech]

2017 Sierra, 5.3 Gen V. New engine installed last week, 5.3 built bottom end BTR Phase 1 PDS cam, Locked out, GPI ported heads, LT4 Injectors and HPFP. Existing Mods TVS 2650 headers and CAI. New engine goes in using a local shop. Drove in towed out. After fixing the mechanical issues .. Ive been struglling with the Tune.
My big issue right now is the Fuel pressure is maxxed at 95050 which some research told me their is an issue with the Sensor and harness which I am diggin into. Search here foind me 3 threads with no clear outcome. If anyone knows what this indicates please LMK.. they reportedly put the original FP sensor in after the new one was wrong..

In any event, truck starts now but idles poorly and seems to search. Ive made a lot of changes which I will sumerise. in an attachment, but tldr injector and pump data coped over form a zl1, base and rolling idle jumpted 250 rpm, DOD disabled Codes for actuator 10 and 11 removed for locked out cam. Crank mode Airflow base +20% added to the entire table. Phaser tables for VVTi 0'd out.

attached in the tune and a few log files.. Any insight into addressing the FP issue (95050 PSI) or other tun fule improments that can be made to help with idle tuning would be immensely appreciated.

thank you in advance

[edcmat-l1]

Need to fix the fuel pressure issue before you attempt any tuning. You're most likely making changes you'll have to undo once it's fixed.

There is some differences in harness and FP sensors I'm pretty sure. Make sure you haven't replaced one or the other with an incorrect unit. I'd bet it you installed a complete LT4 setup you used the LT4 sensor and you probably need to go back to the one that goes with the truck.

I see you bumped those other threads that mention the same 95050 PSI. You need to pull a wiring diagram for your truck for that circuit. Then pull your blower off and figure out what you have.

It's going to be an issue with the wrong sensor or wiring or both.

[Xlexustech]

Need to fix the fuel pressure issue before you attempt any tuning. You're most likely making changes you'll have to undo once it's fixed.

There is some differences in harness and FP sensors I'm pretty sure. Make sure you haven't replaced one or the other with an incorrect unit. I'd bet it you installed a complete LT4 setup you used the LT4 sensor and you probably need to go back to the one that goes with the truck.

I see you bumped those other threads that mention the same 95050 PSI. You need to pull a wiring diagram for your truck for that circuit. Then pull your blower off and figure out what you have.

It's going to be an issue with the wrong sensor or wiring or both.

Yes some background on the install. Truck has 51k on it with the blower for the last 10k The installer of the engine seems to have been 'unkind' with the harness.. amung other things I am addressing. ive already fixed 2 wires that appear to have been poked with a test light and damaged. Drove truck to shop and towed it home. God willing ill find the sensor unplugged. But I am not counting on it ,,

[Xlexustech]

pulled the blower off... put a new sensor in.. same problem.. ws inspected while apart. Its possiable I am using the wrong PID.. but Ive tried to identify that with no success. Its not thowing a code. That said truck will start and rough idle now but is in Limp mode. If I pull it out of limp mode by removig the DTC (its for a cama actuator and this one is locked out) truck will not start.
My therory being in LIMP mode its running off a subset of tables.. and when i remove the DTC its running off the full set of tables and they are way off. Logs and tune files for this attempt attahced. Feeedback welcom

[edcmat-l1]

You have your stock unmodified tune file?

Can you post a pic of the CAI? Remember it has to be pretty small. Can't be a hi res pic.

It looks in the data log like it may have an actual miss. Kind of hard to tell with the wany it's idling.

[Xlexustech]

Ill attach files. Background the truck has been running with the CAI and the Magnuson for a year. With the attached tune names read ect. I went through the entire tune starting with the base file last night. when cold Truck starts right up idles decent. When its gets to around 110 F it starts to rough idle. Here is the current thinking. I put in a second High side FP sensor. A second stock l83. the Truck is in reduced power mode due to DTC P128F. If I enable DTC 128F the truck will not start.
Could the l83 sensor be getting overrun by the new HPFP pressure which is higher? That would pin it I woudl imagine and give me the 95050 value.
Perhaps I need and Lt4 pressure sensor? I looked it up they do come in 3 wire.read-8-3-24-207-gmc-sierra.hptReBase-InjectorData-9-FTrims-MAF-300.400.hpt

[edcmat-l1]

I think you need the sensor that goes with the vehicle/PCM combination.

Break out the multi meter and do some testing.

[Xlexustech]

easier said then done lol. the super charger is not easily removed and sits over this sensor. I am unsure what back probing the sensor would tell me other then is it open circuit and is it getting reference voltage. I ordered the zl1 pressure sensor. They are both 3 wire. The difference between them is the pressure they can handle. Both vehicles use the E92A ECU.

[Xlexustech]

Update, the FP sensor is a 3 wire unit. Black / green gound, Tan/Red 5v source, Blue/ WHite. signal our form sensor.
I have 5 V on both B/w and T/R. Indicating to me that the blue/white was shorted in the harness somewhere. Ran a new wire from B/W to Pin 2 on Ecu.
No Longer have 5V at B/w >
HOWEVER. HP tunners in scanner still say 95050 for the PID.. is it possiable that HP tuners or the ECU are holding on to this value ? Before I put the blower back on I want to get that answer.

My next step is a 1K ohm resistor between bl/gn and B/W... Edit still showing 95050 in HP tuners wit 1k resosr installed. .. next step pin p voltage ck wirh resistor.. man this is kilimg me

Edit .. had a Spare ECU swapped it in and geting expected values ECU is hosed.. .

[edcmat-l1]

No.

It's ridiculous to think you have a wire shorted in the harness somewhere and it has exactly 5 volts on that circuit. It sounds like you aren't checking it the way you should or you're not describing it correctly, etc.

You need a second scanner for a sanity check.

A 3 wire 5 volt sensor is super easy to diagnose in general. Without even knowing how it operates (high to low or vs versa) all you need to do or know is how to read a scanner value then unplug it, check a reading, then ground the sig return, check a reading.

[Xlexustech]

well having a entire spare harness avialbe to me (came out of the donor motor) here is what I can tell you. The three wires form that sensor are interwond throughout the entire harness. literlly twisted together. I just had the engine removed and the new one put in. Their was Ample opportunity to pinch stretch or any number of things to that harness and have those wires shorted to one another. Ive already run a new wire form the sensor to pin #2 on the ecu. With ECU 1 I get 95050 value in HPT, with the spare ECU I get 0 PSI (as expected) This isolates the issue to the ECM’s input circuit on Pin 2, which may have been damaged by the previous 5V short.

I am 100% open to feedback on alternative theories / ideas. i really really need to get this right.

[RDF1]

Some ECM's will have "pull up resistors" So its possible to see 5 volts on the Signal pin.

[Xlexustech]

Some ECM's will have "pull up resistors" So its possible to see 5 volts on the Signal pin.

Agreed but it will be a % of the 5v usually less then 75%

Ck this out... before and after..
FUEL Press.jpg

[blindsquirrel]

Agreed but it will be a % of the 5v usually less then 75%

Ck this out... before and after..
FUEL Press.jpg

No.

Open circuit, if there is a pullup resistor inside for the signal pin, it will read exactly the same voltage as whatever rail the pullup resistor comes from. Because when open circuit there is zero current flow, which means no voltage drop through the resistor, which means voltage input to the resistor is the same as voltage output from the resistor. You don't understand these circuits well enough to call a 'bad ECM', or to check the harness off as 'OK'.

[Blanca_z06]

Agreed but it will be a % of the 5v usually less then 75%

Ck this out... before and after..
FUEL Press.jpg

negative , ref V is 5v , signal wire OPEN circuit should be like 4.98-96 . Checking a signal or reference voltage with an OPEN circuit doesn't really tell you much either , other than the wire is not broken. If it has resistance in the circuit you wont see it till you complete the circuit.

[Xlexustech]

ok after getting some of my testing tools sorted (changed my fluke to my older one (88) I get 5v at tan red and 4.5 V at blue wile all circuts connected.
I am stil getting 95050 with several known good CHannels and layouts. I am now confident that the sensor is doin its thing correctly. My last test is going to be to backprobe the ECU to verify that 4.5 volts is making it there. If that checks out.. then I have no other idea other then ECU.. Please provide any insight that might help .. my truck has been down 2 weeks now and its getting un manageable . Thank in advance for any help.

[edcmat-l1]

It's not the ECU.

You need to check your scanner reading with the circuit open (sensor unplugged) and then with the signal return circuit grounded. You will not hurt anything grounding the signal return.

[Xlexustech]

It's not the ECU.

You need to check your scanner reading with the circuit open (sensor unplugged) and then with the signal return circuit grounded. You will not hurt anything grounding the signal return.

OK Ill give that a shot.. thanks for the input.

[Xlexustech]

It's not the ECU.

You need to check your scanner reading with the circuit open (sensor unplugged) and then with the signal return circuit grounded. You will not hurt anything grounding the signal return.

95050 open and grounded, no change. I dont seem to be getting a 5V 'pullup' Ive traced Sensor out (Bl/Wht) X1 pin 41 0 ohms form Pin to connector. Sensor Ground is good o ohms to Batt Neg. Sensor 5v reference Tn/Red to X2 pin 18 0 Ohms.
I traced all sensors that share the 5v, I tried isolating each one .. I suspect the ECU i in lock doen mode not sending the 5V referance ... but I a still plugging away trying to find the answer.

[gtstorey]

I doubt any of the pin this and circuit that means much to anyone without a wiring diagram to go with it for us to look at. Maybe the guys that do this professionally can, but don’t I keep this in memory.