Earthrealm,
I have always bought Denso brand sensors no matter where they were purchased from. My lights came back on the other day, it ran super rough and was dumping fuel for a few days, and now has cleared itself back up again to where the lights stayed off. Fuel trims are still in the +15-20 range now though. And when i did get codes, this time it was P0172 & P0175, so its a little different than the original issues. At this point I'm still not sure what the root cause is of all of these issues. I may try to clean my ecu connections back up again just to see if that changes fuel trims again.

so i went on a 340 mile round trip over the weekend, and midway through the trip, the car struggled to accelerate past 45mph, a scan show an additional p0171, in addition to the existing p0174 and intermittent p0430. I had previously chnanged the downstream bank 2 O2 sensor, and CEL remained

I had already bought 6 remanned injectors from ebay, installed them yesterday, and all my lean codes & error codes are gone. my fuel trims are now normal, less than 2%, and am super stoked.

replacing the injectors, took me about 4hrs, cos of some stubborn fasteners, and i had to go out to buy 8mm allen key.
subsequent swaps shud take an hour or 90mins tops.

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Awesome news earthrealm! If you don't mind to report back, let me know how your rig is still doing. I don't drive mine much anymore due to having a work provided vehicle, but i had the problem again yesterday when driving it for the first time in a while. Driving along and it felt like the truck didn't want to accelerate and was running really rough. Plugged up the scanner and loaded up torque pro and it was dumping fuel again. Its got to be something like an intermittently sticking injector... just was leery of the ebay denso ones...

Had the same strong exhaust odour on cold start and when under heavy acceleration similar to what others have experienced.

I changed MAF sensor, O2 Sensors, PCV and cleaned the throttle body. Checked and replaced old hardened vacuum hoses and cleaned the intake manifold. All revealed to be temporary fixes. Finally during a recent oil change I found that the rubber seal on the oil filler cap was compressed and as hard as plastic.and the cap had viabrated loose. I also found the inside of tail pipe had sooted indicating to me that it was running rich. I fitted a new filler cap that had an improved rubber seal and after a 200+ mile run at speed and heavy engine loading I couldn't detect the smell of unburnt fuel. I also cleaned the soot from the tail pipe before the drive and on my return the tailpipe was clean as a whistle.

I'm no expert, but it's been the only thing I've done that has stopped the unburnt gas odour. Let's hope it stays that way.

For a small $$ outlay it's worth a look and a try of the oil filler cap fix.

Mine is a 2003 model with 180K miles on the odo. Although it regularly pumped out the gas odour the engine ran well and gas consumption was ok.

Still having this issue. Everything that I have tried so far through this tread has seemed to be a temporary fix. Anyone have any updates on what they have tried and still going strong?

did any body find a fix for this code P0174

OP, did you ever end up replacing your injectors?? I read your entire thread and was left curious. Obviously I’m having your exact same issues.

I replace the 02 sensor driver side rear back in august 2021 when I got the p0174 and now in September 2022 that I got the same code p0174

This video looks like a pretty good guide for anyone who wants to replace their injectors. I haven't done it but was interested in the process.

Hi, I am from Kazakhstan, and I have 2004 4runner with 191 000 miles on ODO.
Have the same issue for about 1 year. Changed all fuel injectors, vacuum pipes. All A/F and oxygen sensors are OK. I only didn't check fuel pressure, because I think it would be affect other bank too, but I have issue only on Bank 2. And also replaced engine coolant temperature sensor. Nothing took any effect on fixing this terrible P0174 error. It only increased power and milage for a little.
LTFT and STFT on Bank 2 were about 29% and sympthoms like a strong smell and rough idle. Swapping of A/F sensor didn't help.
Last week I happened to see Catalytic System Cleaner from Liqui Moly and decided to try it. I filled full fuel tank with it and started to watch for STFT and LTFT while driving. They gradually returned to normal values. It seems my cat was clogged. I will keep observing...

Just a quick update. Car is still throwing P0172 & P0175 codes. I have not changed out injectors yet, or anything else at this time.

I am now following the 2 threads below and will likely purchase a new transmission wiring harness after I confirm that the transmission plug is full of transmission fluid. I still have oil in the ECU and in the front A/F Connectors, so this has to be a problem, even if its not the full issue i'm experiencing.. Going to attempt to fix this first and then proceed from there if that doesn't clear up the issues.

Oil wicking into ECM - random A/F sensor codes P0171/P0174/P2195/P2197 | IH8MUD Forum

and this one

oil wicking up my o2 sensor wire harness?

I'll keep you posted once I find time to get the parts and replace myself, and be sure to follow along in the other threads as well, hopefully this will help someone else out!

Have you checked the catalytic converters? A plugged cat would cause all the issues you're having. What happens is tricky to diagnose and most mechanics won't understand this sh1t. This has more to do with science and math. So with a restricted cat that is not flowing properly and not burning off the noxious hydrocarbons it's building up back pressure in front of the cat as the engine heats up. The unburnt hc's back pressure build back up into your engine diluting your a/f ratio. The upstream a/f sensor detects this as not receiving enough fuel for complete combustion to maintain stoichiometric ratio. Also tricking the MAFs barometric pressure reading and PCM into dumping more fuel to correct the ratio. When in fact you're actually not getting enough oxygen. So you get the rich code throwing your diagnosis off course. Also this causes the misfire and associated trouble code. You have a live data scanner so it's simple to check via MAF barometric pressure signal and O2 up/downstream signals. Or you can remove the upstream and install a pressure gauge to find out. It's been a long time you've had this issue it looks like, hopefully you haven't caked your vitals up. I believe someone on this thread with the same problems mentioned he ran cat cleaner and it solved the issues. Might wanna give them a check since you've already replaced everything else. 👍

I do think the issue is most likely with the oil affecting the o2 sensor harness at the ecm....However I would definitely run a can of redline through the system. It will do no harm and will not cost you any labor time...You absolutely could have an issue with the injectors....even a bad spray pattern could cause issues and the excess fuel could register as lean from o2 sensors as it is UNBURNED oxygen...and this can definitely poison your o2 sensors....

I would run a can of redline through it and give it the old italian tuneup....get those rpms up high with that cleaner in the system...I do think Jake could be right as well with cat but i believe you replaced cat 4 years ago? even so you can test cat by getting engine warmed up and cats nice and hot....then get a temp gun and point it right before the cat and right after the cat....before the cat should be cooler than the temp after the cat...