Weird fuel trims. Need help determining if injectors need inspected or just a KAM reset?

[marshallma0504]

Hello everyone, as some of you may know I recently went through the audacious task of replacing both turbos and timing chains as well, and also my catalytic converters as I had a below efficiency code for bank two. (Both cars had 2 turbos fail through them.) So I replaced both converters that code has since gone away and the voltage of the O2 sensors seems to correspond with normal. What I was recently dealing with was the known issue of the fuel pump control module where sometimes I would go to start the car and it would crank and nothing would happen as well as sometimes especially under medium to heavy throttle, the car would feel like it had almost like a cough or a hiccuping sensation like it was losing fuel pressure. No misfire codes were found or events. So, I replaced that module and below I have attached some pictures of readings I was getting from low to medium to high speed with also a fuel pressure reading in there that was taken at about 40% throttle getting up to speed. My long trims are way out of whack stuck in the high positive numbers only dropping as low as +10 when I was monitoring them. When I did the timing chains and the converters a couple weeks later, I had a misfire incident and pulled the plugs and they were not wet nor had white or carbon buildup. Just looked normal. They are NGK Ruthenium’s with 15k ish miles. The short trims however, as the pictures will show stayed mostly at zero and went negative under letting off of the throttle and deceleration, but always came back quickly and settled back at zero. I apologize for the long read. There’s a lot of information that goes into the fuel trims that I am not familiar with so if anyone could chime in with opinions on what I should do if I should just try a KAM reset and see how that does for the LTFT’s or if I should take my car into a quality shop and have the injectors tested for either being clogged leaking or a combination. 138k 2013 non PP with no drivability issues at this time though. The hiccuping sensation was gone on today’s test drive after installing the new module, just some slight hesitation from a dig when I went 75% throttle on it. And as relating to my previous thread from a month or two ago, I got a new clamp for my CAC to throttle body pipe and it’s tightly seated. Doesn’t seem to have any vacuum leaks at the moment by visual inspection.

 

[Texas Marauder]

IMO, no CEL, no worries. My stock car, 114k, also has high LTFT, varying between +8 to +12. STFT is typically 0 to +2.

 

[marshallma0504]

IMO, no CEL, no worries. My stock car, 114k, also has high LTFT, varying between +8 to +12. STFT is typically 0 to +2.

Mine is also stock. Replacement turbos were remanufactured OEM units too.

 

[6500rpm]

LTFT at +10 or so and no more fuel being dumped in on the STFT doesn't sound out of the ordinary. Are you sure your not feeling a tcc shudder? When was the last time you changed your trans fluid?

 

[marshallma0504]

LTFT at +10 or so and no more fuel being dumped in on the STFT doesn't sound out of the ordinary. Are you sure your not feeling a tcc shudder? When was the last time you changed your trans fluid?

The stuttering sensation has gotten more constant but only happens under light load like when you get up to 60. The rpm’s jitter down on the tac every few seconds randomly. I changed the trans fluid last year so it might be time. I also just had a P0420 code pop in yesterday. I already replaced the cats so my o2 sensor is next to hopefully fix that and maybe the stuttering will go away I’m hoping. If not I’ll try the trans fluid and see if it looks burnt or brown.

 

[FREAK_SHO]

Do poops and grins, check to make sure the hose (zip tied) in the photo is still attached. This is on top of the intake, under the dress plastic
Bottom center

 

[marshallma0504]

Do poops and grins, check to make sure the hose (zip tied) in the photo is still attached. This is on top of the intake, under the dress plastic
Bottom center
View attachment 94755

I made sure they were when I redid that solenoid during the timing chain rebuild. The p0420 is staying at bay for now after I put some Techron in the tank and put 93 gas in it. I usually run 87 for reference. However the stuttering under light decel makes me think it’s a leaking injector on bank 1. After all that converter did smell like gas when I replaced it. I don’t have the money to do injectors right now so I’m hoping the CEL stays gone and I will do a KAM reset after I put in the new wideband O2 sensor. I cleaned it when I did the converters but maybe it was damaged and only replacing the post cat sensor didn’t solve the issue just mitigated it for 3k miles or so.

 

[Yirmiyahu]

My experience with high LTFT constantly high, at idle, under load of any kind, is actually the high pressure fuel rail sensor of all things. It reads there isn't enough pressure and commands more fuel. It'll actually bypass O2 sensor input and default to rich. It took me a long time to figure it out, and it isn't even me that solved it, other than ruling out fuel module, injectors and the like, it's in a thread. there's a thread on here where a Subaru mechanic with a SHO just couldn't figure out LTFT being high with total fuel trim nearing 20. After he swapped his hpfp and tune back to stock, and it was still the same he realized it wasn't anything we'd typically check. In his confusion he talked to Matt who had suggested the high pressure fuel sensor, low and behold, normal fuel trims. So I recently changed mine and normal fuel trims resulted. Though now I have another issue to chase down, if long terms are high and totals are high, and everything else is ruled out, it's the high pressure fuel sensor not accurately reading the fuel pressure that's actually there. Just thought I'd come in on that issue and offer that experience should if be useful.