Help w/P0171, Leaking Injector Isolators

Just got the truck all back together this morning after a bunch of work over the last few weeks:

• Knock sensors & harness
• Valve adjustment
• Valve cover seals
• Motorwest Denso Injectors (Same flow rate)
• All new intake manifold gaskets
• JBA headers
• New PCV valve, hose, & fresh air hose

The truck started and idled just fine. At low speed & rpm there was no noticeable issues. When trying to get on the throttle, it begins to hesitate and cut off badly around 2.5-3k rpm. Under very slow, steady acceleration it can go higher but will cut again under more throttle. This is somewhere around 3-4lbs of boost from the supercharger. While sitting in the driveway, it can rev up to the redline with no issues or hesitation. See video for how it behaves while driving.
On the first short drive it didn't throw any codes. When I left it idling in the driveway to go get the code reader, it threw a P0171 (Lean Bank 1). On the same short drive route, the STFT and LTFT jump up to 20% while exhibiting the behavior described above. LTFT was constantly up around 20% while driving, STFT jumped all over and stayed around 20% while under any boost and attempting to accelerate.
The truck also has a nearly brand new AEM 340 fuel pump. It was under-fueling badly under boost prior to the install of the AEM pump. Since then (prior to this project) it ran much better.
My understanding is that it most likely to be one of three things: bad MAF sensor, air leak between MAF and supercharger, or some component in the fuel system not keeping up. The new fresh air hose from the driver's side valve cover fits a bit loose on the valve cover fitting, could that cause something this drastic? I'll test that next. After that, MAF and injectors are the next possibilities. It would take some (re)work, but reinstalling the old AISIN injectors is an option. It does seem unlikely that the Motorwest injectors could be bad, but that's the only major fuel system component that was changed. Anything else that could be the culprit?

https://www.youtube.com/shorts/wUaYUBhej9I

 

Update: Cleaned the MAF and added some Gorilla tape to help it seal around the dumb K&N intake tube. It was still spotless from being cleaned 8k ago. MAF at idle (pretty much exactly 1k rpm) was 4.5-4.9 g/s, now closer to 3.8
Capped the PCV fresh air hose and tried without it as well, no change from that.
The issue is probably either fuel pressure or the injectors. I assume it's not necessary to bleed the fuel lines after having them out?

 

Update: Tested for air leaks with brake cleaner as the STFT would drop under slightly higher RPM. It appears to be leaking on the passenger side of the lower intake manifold. The joint between the supercharger and lower intake manifold was also leaking, I was able to tighten it but the lower one still leaks. So the S/C still has to come off to tighten that up. Unfortunately I'm not aware of any way to pressure test that joint without a custom plate to seal it off.
My first assumption was that it couldn't be the manifold joints because it wouldn't pull air in under boost with the manifolds pressurized...maybe it still does? Not sure what to think of that.
Does anyone have any experience with these leaking? I used brand new OEM gaskets, the prescribed torque pattern, and a torque wrench (13 ft lbs). Basically just going to snug them down by feel now. Surfaces were cleaned from residue and wiped down with brake clean prior to installing the lower intake manifold. If this doesn't work I may look for a different kind of gasket than the MLS.

STFT and LTFT are maxed out at idle as well, which is why I'm diagnosing at idle with the brake cleaner. Basically just spraying brake clean (or starting fluid) at every joint until the STFT drops rapidly.

 

Update: Got a smoke tester. What appears to be leaking are the seals around all six fuel injectors. Not the o-rings to seal fuel, but the seats that sit against the lower intake manifold. Planning to pull them tomorrow to try to figure out what went wrong, may borrow the ones off the old injectors.

 

Update: Comparing the Denso to AISIN injectors isn't showing any major differences up front, but the Densos will NOT seal, and the one AISIN I put back in sealed right up. Exact same isolator and everything. Going to give Motorwest a call to get some ideas.

 

Damn
U on it!!!!

im pretty sure you know/did this
(Just asking)
Did you “lube” injector rubber with lil fuel?
Or Petroleum product

 

I did with the Superlube that Motorwest provides. They were very helpful on the phone today and we both concluded that it had to be the lower o rings. Pulled them all out, lubed them up way more than the first time, and after several tries they all seem to have sealed. The front one on the driver's side barely sealed but seems ok. Should be able to fire it up tomorrow to find out.

 

I really love it when u call a vendor and a cool experienced human answers!!!
MW is great

FYI….was told lube rubber with gas
I was HUH? Then found that any petroleum product would do
I used some way expensive AC vacuum pump oil (given to me…I’m too cheap) to
lube my MW RM injectors


saying a prayer for ya!!!!!

 

Got everything put back on and did a final smoke test...Looks like two are still leaking. The middle and farthest to the front on the driver's side. Going to give it one more shot swapping around o-rings and stuff. All three on the passenger side are definitely sealed, they aren't leaking at all now.
I'm at quite a loss for why they are not sealing. The only two major differences I can find is that the Densos are .040 shorter, and have brand new o-rings. The old o-rings on the AISINs actually fit and seal better. Maybe the Denso injectors are just barely sitting deep enough. The one that is having trouble sealing (driver's side front) is the farthest from the bolts and receives the least downward pressure. Pushing on it by hand helps it seal better. The whole system is really pretty scabby for how reliable the rest of the truck is. After seeing how little margin for error they have, and that the isolators do nothing to seal them whatsoever, I'll be very careful washing under the hood in the future. A manifold type connection for the fuel rails and injectors would be much better.
My main fear now is that just one of them will pull a little air, that cylinder will run really lean, and maybe detonate enough to damage that piston. Going to smoke test them all again with the supercharger off tonight, it's not going back on until all those stupid things are 100% sealed this time.

 

well damn.

affected fuel rail isnt getting 'hung up' on something?....preventing the minimal pressure u eluded to seating injectors?
sorry i have 2RZ and not really familiar with v6 fuel rail setup

MW could send you some new/other rubber parts?

 

This is a very rare problem indeed....

only time I' ve ever seen so much.....is there was an old oring crushed down in one of the tubes...
its not so easy to eye that

can't be cups......5vz doesn't have cups...right?

 

i was thinking the same OS.......pretty sure no (not positive thou)

 

No cups on the 5vz, just the o-rings and isolators. Pretty sure the isolators just isolate from vibration and maybe grounding, plus keep some debris out.

Good news is that they finally all sealed. The passenger side all sealed with the supplied o-rings. When testing with the supercharger off again, all three on the driver side were leaking. I happened to find some YT video where a guy used a Fel-Pro part for o-rings. The local O'Reillys had some in stock so I decided to give them a shot, part number ES70600. They are slightly larger and feel like a little higher durometer rubber. They were substantially tighter and ended up sealing right up, no problem. Never would have guessed that the solution would be Chinese made o-rings from the local parts store

Bad news is that the truck is still not running worth a crap under boost. It's doing what it did in the past (before the AEM 340 fuel pump), but much worse. At about 3 psi of boost and ~2800 rpm, it starts cutting out badly like the video above. The difference now is that the fuel trims at idle are near zero. Fuel trims under boost go up (LT ~18%, ST are ~6%) but that doesn't seem too crazy for a supercharged truck under boost. It's better now in that I can inch it past that zone, and at around 4500 rpm and 5 psi everything levels out and it takes off and runs like normal. Since it's a different problem I'll start another thread for the new issue.

My summary for this thread is that it is likely best practice to have a smoke tester on hand when doing any kind of intake/fuel injector work. Only takes a second to get a little piece of mind before assembling everything again. O-rings can be very sensitive and should be lubricated very generously before install.

 

What are you using for ecm??

 

Factory ECM. No 7th injector, piggy back, or anything. Planning on a WOT switch after the manual swap but that's a ways out before I'll have time for it.