04 Corolla Long ft 25%-40%

[APO]

First post and let me say thank you to all who have posted info here. I have been reading these forums for a while but have learned a ton by just reading. No on to my issue...

I get code P0171 which shows a lean condition. I have cleaned, but not replaced the MAF, changed the upstream O2 sensor, replaced plugs, changed the oil of course and cant get the issue solved. My ShortFT hovers around 0, does go up to 11 when hitting the gas on the freeway what returns to around 0 when not punching it my LongFT sits at 29 and jumps to 41-45 at higher RPM's which trips the CEL. Ive checked for leaks and found none. Also I had the stem from the gas tank to the filler changed recently. Basically I had that changed, no problems and 2 weeks later got the CEL for the above code. I needed to get smoged so I cleared the code and it passed smog but the code came right back after. Makes me think it isnt the CAT as I would think it wouldnt have passed smog. I could be wrong. Any ideas or next steps would be great.

 

[Luis0522]

You may have a bad injector,I had the same code on my 01 and I replaced all spark plugs with factory iridium and tested my fuel injectors. Cylinder 1 on mine was not pulsing the same as the others, of course this was my last resort before that I checked for any intake or exhaust leaks, replaced upstream O2 do to a lazy sensor. After I swapped my suspected fuel injector for a known good one my fuel trims returned to normal and never go the light back on.
Check your data and see if you have any certain misfires at times in any of the cylinders this may help narrow it down if an injector is your problem.

 

[APO]

Thanks for the reply. Switching out the injectors is next as it is the last low cost option I believe. So far I have changed the plugs, pcv valve, upstream 02 sensor,cleaned the maf and just replaced the intake manifold gasket. Did the gasket today as the car died on me on the way to work. It just couldnt hold enough rpms so when I came to a stop it would die and start right back up. Searched online and found the gasket could be the culprit. The idle has returned to normal/better than it had been in a while but I still get the lean condition with longft ranging from 25 to 42. The only time I got missfire is right after I put the gasket in and cleaned the throttle body. I had to gas it to get it to start and got a couple pending codes. I cleared those after about 15 mile and then drove about 10 more mile with a lot more high rev stuff and they have not returned. Like I said, injectors are next but any other ideas would be great. Also my shortft is within acceptable range.

 

[APO]

I should note that when I pulled the manifold off the part of the engine behind it all the way on the passenger side you could see signs of what looks like excessive heat. Basically the metal under that far passenger side spark plug was a good bit more brown than the others. Not sure if that is a sign of something with that cylinder/injector. Opinions?

 

[Luis0522]

Not sure either but if you injector is not spraying as much as it should this could cause that lean condition and more heat to that area. If everything is fine leave it for now until it acts up again. Also about your intake gasket even though you replaced you should to check for leaks my intake gasket was still leaking after I replaced it so I double gasketed it. Not recommended by my intake was so warped this was my only fix.