2014 Silverado 5.3L P0172
have been working on this truck for a few weeks on and off. originally came in for check engine light, and general check over. first code was P219A fuel system imbalance. truck had 133k on it and no maintenance, replaced plugs, wires, cleaned carbon form throttle body and performed BG top end cleaning. cleared light, fuel trims seemed to be ok then and ran a drive cycle on it and got monitors ready pretty quick for state inspection. week or so later comes back for check engine light and had the P0172 code, left bank seemed to be missing, number 7 was the worst. checked vacuum leaks and ran basic tests and check pcv system for fuel contamination, all ok. replace left bank injectors with OE. misfire gone. fuel trims pegged at -35 LTFT bank one. mass air flow clean, reading in the 5g/sec at idle. picture of intake valve is after BG (yes i picked out part of my flashlight laying in there) not sure it did much in the way of cleaning. snapshot of my current data. after injector replacement still having high trim numbers on bank 1. blocked off purge valve also, no change. just looking for a direction. thanks.
Exhaust leak possible on bank 1 ? I usually reset fuel trims and monitor 02 voltage for bias.
Did you check those old injector part numbers (stamped on injector)? There are three different flow rates (low,nominal,high) You need to make sure you installed the correct flow rate or the problems you are having may occur. Check out tsb#20-na-098
Interesting. I don’t think they gave me a choice on injectors.
Although I've had different injectors on the same engine in the past, I did a 17' today and the parts department told me they only had one listing for the injector after I asked about different flow rates.
Data in the image is just after trim reset. Don’t hear or see much wrong with exhaust but I could smoke check it
Daniel Check alcohol content on scanner PID. Also make sure they didn’t cross O2 harnesses after last transmission work
Scan tool should allow you to do an injector flow test FYI. Ive had a very similar problem last week on a 110k 2017 except its both banks… even after plugs, HPFP, and B1 injector replacement manual valve cleaning(by hand) and oil change. Confirmed purge valve sealed, swapped MAF from known good truck…. Same reading as yours. 4.7-5g/s at idle. 15% load. The customer did not want to proceed…
I feel you pain… been through this scenario couple weeks ago. youtu.be/53KDnvnIqF4 Changed out all 8 injectors and carbon cleaned the intake valves with walnut blaster. Fuel trims were not much better afterwards but at least didn't set the P219B code. Here's the injector Replacement and cleaning. youtu.be/PXJXpfg_AYo That was a huge PITA. I ran the injector flow…
Daniel Earlier I forgot to ask, what did freeze frame data indicate when the code(s) was set? Idle conditions? Cruise?
Code sets at idle. The p0172. Almost instantly hits -35% at start up
Bank one is -35% ltft. Which is setting the light currently. Bank 2 hits -14%. But I’m assuming that’s gonna be my next problem if I get through bank 1
So you DO have something that affects both banks…would have been nice to know that. I would not ‘get through’ Bank 1 and then try to resolve Bank 2. You've installed the issue on Bank 1, and it appears Bank 2 is not far behind…I would see if you can create a vacuum leak and see whether the trims respond, just to eliminate some weirdness on the whole system. Since the injectors are having an…
I agree. I just thrown off by the huge difference in trims
Try disconnecting the PCV hose from the vacuum source at the intake, then reset the fuel trims and allow the engine to achieve closed loop. If your bank 1 fuel trims return to normal, you may have a high pressure fuel pump leaking. If the PCV was picking up the leaking fuel and drawing it into the intake, the fuel may not be detectable in the engine oil.
I would check exhaust back pressure just to rule out restricted converters
Not going to be a composition reset, that would affect both banks. Possible O2 sensor issue, but am doubtful. Compare front O2 to rear on that bank. Rear flat-lined lean and front rich after trim reset, indicates an O2 issue. BG intake cleaning is a joke, and would not cause trims to be -35 on one bank either. Clogged cat would cause lean trims on the opposing bank, and not negative trims to…
I would check oil for fuel contamination. If so, the high pressure fuel pump could be leaking causing the high trims.
Daniel Forgot to ask: Since you replaced the GDI injectors does this engine also have a set of conventional injectors spraying on the intake valves? If not I think many in this thread probably already have the answer: the high pressure pump is probably leaking fuel into the engine oil (fuel dilution)
Truck does not have dual injection system. Plugging the PCV may reveal the answer as far as the HPFP is concerned…
You definitely have something affecting both banks, try as the others have said to disconnect pcv and run it and see if fuel trims come back.
so i did the PCV thing, no change in trims, went back to investigate a little further on the injector part numbers and the part removed was … which according to GM is for the V6? show's a quantity of 6 when ordering. the injectors i put in were … which show as Nominal flow injectors. my part number does not show up under the 3 choices. according to my tech the white sealing o rings…
Neither of those part numbers are valid for this truck. The ‘1262’ number does not come up on a GM parts catalog check, but shows as an AM ‘ebay’ sort of thing. The injectors you installed, come up as an injector for a Corvette. It would appear that you need all eight injectors for the correct application…someone has obviously been installing AM crap in there, which would explain a whole lot…
Replaced Left bank injectors only as a social experiment and LTFT is hovering in the -14% range bank 1 bank 2 is in the -9% range.