08 toyota camry se p0171 code. Replaced MAF, intake, plugs, cleaned throttle body, need to asses fuel system and evap

Asked by Oct 01, 2017 at 03:29 PM about the 2008 Toyota Camry

Question type: Maintenance & Repair

It all began with having difficulty starting.. the car would turn over for awhile
but not start i could pump on the gas a bit and try again after a few mins,
and then it would fire up.  Someone suggested a fuel pump, but it seemed
to be working fine at this point, so unless it was intermittent than I seriously
doubted this issue (besides its expensive as heck for this car so lets avoid
that if we can). Anyway, the problem worsened and after driving for 20 miles
and parking, if i killed the car it would not start again for a half hour. Soon
after, i noticed performance issues for the first time: bogging down on the
freeway, sometimes i would gas it and it seemed to be sucking down plenty
of 02 but no fuel. However, my fuel efficiency was out the window and
declining fast. CEL came on about this time and showed a p0171 bank one
sensor one lean code.. As i suspected, the air to fuel ratio was whack, but
many argued this was no fault of  the AF ratio sensor or bank one sensor
one (If Im not mistaken also known as the upstream 02 sensor). I clearly
have a fuel delivery system issue or evap issue and also I decided,
(especially since this car had an oil consumption issue and recall a year or
more ago) that it needed a good cleaning and a lil TLC. So i replaced all
plugs, checked the coil packs, cleaned the throttle body, and replaced the
MAF. Now my car starts like a champ, but rpms are an inconsistent
nightmare... Once, after start up, it revved way up to 3500 on its own.
Another time, the rpms were falling to idle at around 500 and the throttle
would die if i attempted any sort of movement (this was before the tlc and it
hasn't had the issue of low rpms since). I do still have problems with it
bogging down occasionally on the freeway and a few other noticeable
remaining intermittent problems. I checked my fuses and connections right
then, and found a couple anomalies and i cant for the life of me figure out
why but there was a few missing fuses. It was the AM2 & IGN which would
both explain issues with difficulty starting and inconsistent RPMs, if these
were in fact missing fuses. Last... I traced the connections and evap, and in
the back against the fire wall i have a single wire connector that isn't
plugged into anything.

If anyone thinks they know what my P0171 could be or what is going on with
my car's idle, throttle, and start up issues? Any ways i hope you have as
much fun trying to diagnose this as i have.....

18 Answers


Have you checked for a vacuum leak first? Second have you checked your O2 sensors on live data? Are they switching values?

How would i go about checking for vacuum leaks on this vehicle, i have found no go to on the topic. before doing a test, two problem areas i want to adress- i want to replace the pcv hose and also as i replacing the air filter i first noticed there is a bolt missing on the housing lid that i am trying to match for replacement. after replacing these two things i will check for other leaks. when checking the O2 sensors live data i want sensor 1 to fluctuate and sensor 2 should be high and flatlined, correct?


You would have to do a smoke test. Lots of easy ways to make one. YouTube is your friend here. O2 sensors are correct on your values. I think you could be on your way to solving part of your issue with a new bolt. Your car could be getting too much air and is running lean. Another scenario of this is that you have an air blockage and not enough fuel also giving you a 171 lean code.


Has the PCV ever been changed? This could be clogged. Are you using any oil. Oil usage is sometimes relative to PCV function.


Lean code and smoke machine. https://youtu.be/HcZohs1crFs


Toyota P0171 https://youtu.be/d4wNywEo1o8

1 people found this helpful.

ok @Guru sorry for the hang time but were gonna see this one through, i ensure you. This is where were at now... ill try and remember to include the pictures for shock value but you were right to look towards the pcv. Now let me tell you... That boy was FILTHY. d be surprised if it was moving at all, now stuck open or closed i wouldnt know but the crankcase looks pretty rough, is this normal? OK or safe at least. the house was split pretty badly too so even if the pcv was stuck closed the pressure would have been seeping out through the bad hose. however considering the lean code i guess it would make more sense if it was stuck wide open on top of a bad hose creating a lean mess. i believe i finally found a suitable replacement for the airbox's missing hardware too.I would like to find an OEM here as its an freakin odd size screw and thread pat; but what i've got for now is pretty damn similar where it counts! i also replaced the hose with a 3/8 ID hose.. i actually found a quality fuel line generic or universal type here and its OD is much fatter than before but only adds to longevity i would imagine... however this presents the issue of not being able to reuse the old clippage. I am going to grab a couple over sized pinching clamps.. ive double checked, visually anyways, the rest of the intake system and seems to be lookin good- so now I am cleaning up my pcv (likely will order a new one considering the extremely modest price tag, just hate to wait anylonger, Maybe I do a Smoke test while i wait.


Carpe.....what's new on this interesting problem you are having with this vehicle?

i have oem pcv valve, and hose (cleaver bastards made a half SAE 3/8 x 15mm, half metric hose) in transit from amazon, as well as an exact fitment air/fuel ratio sensor... typically your upstream o2 sensor and just about one of the hardest to find specifically for this year and trim (i went with the denso 234 9049, yes i have cali emissions too) all will arrive friday and the moment of truth will follow. In the meantime i've cleaned up engine, replaced the missing bolt on the back side of my air filter housing and put some sort of contact butter on all my pertinent electrical connections; and now we wait. Anything you can think of that i missed... i have my readings (just before this second round of repairs were started) on the fuel trims and now - oxygen sensors @idle and @2000 rpm both sensors DID fluctuate or, cycle, constantly and also appeared lazy. I only ordered the harder to find afr sensor for now as the downstream would be no issue to obtain later if the need become apparent. Moving on (filthy crankcase looks as bad inside as the valve does outside) i'll add these pictures later. PCV hose was in pretty rough shape split with a wide gash under valve nipple, and the air box (missing back side bolt) wide open. i think this all played a role in lean system... i have fuel trims somewhere if anyone can use that to diagnose a bit more. also while checking all fuses i couldn't help but notice removing efi 1 - caused a very loud electrical buzzing or whining to immediately stop.. upon further inspection i have noticed same injector seems loose ( no e-clips i can see above or below, not sure what it usually has- this may all be normal and id be known the wiser.) and lastly - When i pulled the plastic cap off the top of the fuel pulsation dampener i kid you not that screw was hanging by a thread or two... i have a gut feeling this things got a specific torque setting, i would appreciate any tips or pointers here as well

I've got some more pictures to add and also received all the parts i ordered, just this morning + a new obd2 bluetooth scan tool. TBH repairs did not yield desired results... could I have possibly over tightened the fuel pulsation dampener, essentially cutting off my fuel supply to rail/ efi's. I hope so or maybe car needs to run a full cycle. however I'm tired and slightly disappointed... I'll fill you in later today. Never give up... never surrender.


What engine is in this vehicle?


A 2008 is the 2.4 4 cylinder. I think it is the 4 banger


That 2.4L is a known oil burner which will cause many of the issues you are experiencing. Fouling the AFR sensors is one of the effects of excessive oil consumption. Did you ever receive a notice from Toyota concerning this issue? GOOGLE...Toyota..excessive oil consumption. Get back with resilts.


Another idea. Excessive OC could plug the CAT...catalytic converter...causing starting and drive ability issues.

1 people found this helpful.

My car has a 2AZ-FE 2.4L 4cyl engine. I have heard of the oil consumption issues, and my car was brought in to Toyota, in response to the Technical Service Bulletin they issued about OC problem, in order for them to change the pistons. They claim the piston assembly was modified to minimize oil consumption, and "burning 1 quart per 1,200 miles of operation" is SOP. Right... anyways. Here are some pictures. The car is still running/idling rough, and when pressing lightly on the gas pedal it begins to stall out and die, but if the pedal is pressed in quick, rapid successions, it juices up to life. Causes?

Also here's a pic of the fuel dampener I mentioned earlier, feeling like I'm not getting enough fuel, is it possibly overtightened or am I good here?

I was under the impression the previous/ original owner (who I happen to know) had changed out the catalytic converter, or had the cat replaced when he had the oil consumption TSB addressed. This however was incorrect information and the car , w/ over 200500 miles now has the original sorry-ass-CAT on it and is no doubt "shot-to-shit". no cat replacement ever took place, in fact the service bulletin was hardly an engine rebuild at that... the story goes something like this... They picked the car up from the dealership after they swapped the undersized pistons and rings out for some new ones (if I'm not mistaken I read this somewhere that they were replaced with pistons that should have been stock in the first place sizing up a half mm larger than the wee pistons that rolled out of production) and almost immediately after returning home noticed the car to be smoking something or another and they proceeded to do what any self-respecting, dissatisfied customer would do... complained to management! This confrontation was commonplace to Toyota management around this time I AM SURE they received a few hundred thousand of these a week and anyways Mr. Management was quick to dish out a free valve job and a small handful of gaskets.. oh wait no gaskets. hm. Problem solved?


Wow..... interesting history. Regarding the fuel system pulsation dampner. I have never tampered with that screw. My guess it might adjust the tension on a spring inside the device. I would be inclined to install a fuel pressure gauge in the fuel delivery line and check pressures against specs. The CAT can be checked with another low pressure gauge in the pre CAT o2 sensor hole.PSI before the CAT should be less than 3 psi. I would also pull the spark plugs for inspection to if they are gas or oil fould. Keep us up to date on this interesting vehicle.

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