P0174 Code and intermittent sputtering

To be thorough I plan to put a homemade smoke machine together than test the vacuum lines. Also plan to buy a fuel injection test kit and test the fuel pump. The P0441 and P0455 came back as well but now that I’m thinking I believe the ECM is thinking I have a massive leak because LongFT1 is far behind LongFT2 now.

What’s still crazy to me is if I have a leak that large you’d think I’d hear/see/smell it. I’m kinda hoping it is the fuel pump now because if not, this is one massively evasive, yet intense vac leak. Outside of a cold start idle that may be 2-3pm higher than normal, the truck settles out back around 600 rpm at idle when warm and doesn’t miss a beat when driving

I’ll report back soon

 

Stupid question but have you checked for holes in the tank (i.e. crackhead was going to steal your gas), or squirrels chewing on the fittings, which we’ve seen way too much, even @abcinv threw codes because they chewed up his filler neck? Do you park outdoors, ever, for 1-2hr or more where that could happen? Have you smelled around under the truck for gas after the truck has been sitting for a while?

 

It’s outdoors 99% of time. However I previously checked for rodent nests on top of the tank and saw nothing. Have also checked the soy-based fittings, hoses etc and also have found nothing.

No in gas tank, no signs of gas leakage, fuel filler neck seemed fine. I didn’t get close to the filler neck so I suppose I can get a tad bit closer but it looked fine. Unless I’m missing something, I really hope it’s either a small (but intense) vac leak or the pump itself. It’s weird

 

I’d just forego the head scratching and smoke test it. Test it at the test port in the engine bay, driver side, and also test directly at the gas cap.

It should highlight where your problem is.

 

Update #2:

So I’ll try to keep it short and sweet,

Finally got around test the fuel pressure. Got up to 42 psi at idle and then down to 29-30 psi 5 minutes post-shutdown. As far as that test the fuel pump seems fine…





Done a smoke test with the homemade smoke machine (slight shit show at the end) and saw absolutely nothing. Made sure intake and TB were closed off completely. No smoke. HOWEVER, unlike last time, I happen to see the slightest nick in the PCV hose. I only saw it because condensation was flowing towards it. Looked dry inside and when I flexed the hose I couldn’t see anything. Smoked it on its own and I’m almost certain no smoke released. I patched and taped the nick temporarily.

Now here’s what’s weird. On my first update I pulled all EVAP hoses in the bay and re-inspected them. When input them back and checked scanner for giggles, the SHRTFTs were running really rich. Like the PCM was trying to finally balance out the LONGs.



Each time I shut off and restarted, The LONGs got marginally better. Almost like I “burped” the EVAP lines. Not sure if that’s the case or it’s the PCV hose but my numbers are looking a lot more acceptable. Hasn’t had time to drive her around. Will do that then report back if this is resolved or not.


Side note: considering I’m just shy of 200k, Now I’m wondering if I’m an idiot and if the 3 stammering starts are actually a slowly failing starter…

 

Show us how that pressure gauge is hooked up to the fuel rail.

 

Removed the 17mm bolt on Bank 1s side and attached a schrader there. Probably should have done it on Bank 2s side but hopefully it won’t matter.

 

Update: So it’s been a while but I wanted have a thorough response for the threads sake.

The extremely high fuel trims have disappeared. The gas cap, though I couldn’t find a compromise, definitely fixed that. I also replaced the EVAP purge valve which looked relatively new (Doorman part with a Doorman part. Couldn’t find a OEM)

The failure to start after fill up has disappeared (so far) if filled up to half and to full a few times just to see if the changes in tank pressure was confined to one or other. Originally any time I filled up to full, she’d hesitate to start. So far she’s done neither.

Short Trims hang out around 0.0. Perfect.
Bank 1s Long Trim settled out around 3.1
Bank 2s Long started at the same 3.1 but has steadily creeped over the weeks and is settled currently at a 9.4. Still no CELs however.

I’m convinced it’s still the fuel pump and that it intermittently struggles to get enough fuel to Bank 2. Could be wrong still but that’s what the history is telling me at this point

 

To me that's saying lean condition, too much air not enough fuel....vacuum leak or faulty O2 sensor.

 

I’d agree but I’ve replaced all but one vacuum hose. The one that rinds from the fuel rail to the back of the intake housing. My plan is to get it when I service the intake and starter soon. So I guess I’m not totally out the woods on hoses but unless it’s the culprit, I’m thinking pump.

my plan is to replace the hose intakes gaskets and starter in the next few weeks. Would rather not pay to replace the starter but considering where it is, if I can get holding a Denso, it wouldn’t make sense not to. Almost sure it’s original.

 

More than likely your battery is on its last leg (CA/CCA low), or you have corrosion inside your cables. Not using felt washers and dielectric terminals will result in corrosion getting inside the wiring.

You're probably overdue to replace much of the rubber hoses in the engine bay. I did both of my PCV breather hoses, there's one coming off each valve cover, though only the driver side has a PCV valve, which I believe is supposed to be replaced proactively (per service schedule?) every 30k or 50k miles, I forget. When I pulled the PCV hoses on my '06 recently, smashing the ends revealed a shedload of cracks. Vacuum leakage would probably account for some of the symptoms you're seeing.

Not sure which hoses you've replaced. Or what you used to replace them (some hose types aren't fuel-safe, others collapse under heat, some collapse under vacuum, so choice is important)

 

Thanks for the insight—yes, the hoses I’ve replaced thus far have been the hose from O’Reily’s that is rated for high pressure fuel usage. The PCV hose on bank two was one of them. To your point, it didn’t show cracking I could see, but it was very rigid. I’ll give battery cables a look as well

When I replace the intake gaskets, last two vac hoses and the PCV valve on bank 1, I’ll report back what I have.