Code:P0171 need some help

[dumpedseegeesix]

Hows it going everyone?? I own a 2000 accord v6 and having some trouble with the car..the check engine light seems to keep coming on for the same code.. when i got the car i replace the timing belt water pump and the tensioner .. after that the car started to trow a code for 2nd gear selonoid and for o2 sensor first bank.. so i replaced those 2 sensors and didnt have any problems with the car for about 2 weeks.. then the problem with the p0171 happened its a lean code.. I replaced the spark plugs and coil packs and also the fuel presure regulator and also changed the gas i put in.. the car was good for about a week then it came back up for the same code but when i changed my gas the light went off on its own..then it happened again yesterday the light was on now it went back off today..Its kind of annoying with the light coming on and off at its own so if anyone has had this same problem please help me out..any ideas would be help full.. and all parts are changed with OEM honda dealer parts

 

[dumpedseegeesix]

someone said to change the 2nd o2 that could be a problem too but i checked it on the machine and its working just fine

 

[001Stunna]

If its coming on and going off on its own i would wait until it comes on and stays on. P0171 would call for the upstream o2 sensor to be changed if its acting lazy. If you do change the upstream sensor use only either OEM or Denso#234-4727 or NGK/NTK#24582 .

Check the front o2 by looking at its graph when holding the rpms at ~3000rpm in neutral or park. It should move up/down constantly and never hang either up or down. If the o2 sensor is working fine then check if the evap purge control valve is holding vacuum from the intake side. If the evap purge control valve checks out then other things to check would be valve clearances, and possibly bad fuel injectors even though the latter 2 are most likely not the issue.

I know the 4cyl accords did have a TSB issued out to change the fuel pressure regulator and re-route the vacuum lines and I see you've changed the FPR already anyways.

To start with easy things first though, throw a can of fuel injector cleaner in your tank (STP, Seafoam, BG44k, Gumout Regane all work fine)...and monitor it.

 

[UTIaccord]

use a multimeter to check the resistance on the reference (voltage supply) and the ground wire, could be a good sensor with bad readings from high resistance in the circuitry

 

[UTIaccord]

also if u have access to a scan tool or someone who has one, check ur air to fuel ratio and the long term/ short term fuel trim

afr should be around 14.7:1

fuel trims should both be near 0

 

[001Stunna]

also if u have access to a scan tool or someone who has one, check ur air to fuel ratio and the long term/ short term fuel trim

afr should be around 14.7:1

fuel trims should both be near 0

LTFT is actually perfectly normal to be in the -8/+8 range...for it to be at 0 would actually be unrealistic as no engine/ecu works that perfectly. STFT should be the one that's not making great movements to further change the LTFT. If STFT and LTFT together are more then +/- 15/20 you've got something weird happening.

A scantool will not tell you actual afr ratios. He'll need a wideband uego sensor and a gauge for that.

 

[dumpedseegeesix]

If its coming on and going off on its own i would wait until it comes on and stays on. P0171 would call for the upstream o2 sensor to be changed if its acting lazy. If you do change the upstream sensor use only either OEM or Denso#234-4727 or NGK/NTK#24582 .

Check the front o2 by looking at its graph when holding the rpms at ~3000rpm in neutral or park. It should move up/down constantly and never hang either up or down. If the o2 sensor is working fine then check if the evap purge control valve is holding vacuum from the intake side. If the evap purge control valve checks out then other things to check would be valve clearances, and possibly bad fuel injectors even though the latter 2 are most likely not the issue.

I know the 4cyl accords did have a TSB issued out to change the fuel pressure regulator and re-route the vacuum lines and I see you've changed the FPR already anyways.

To start with easy things first though, throw a can of fuel injector cleaner in your tank (STP, Seafoam, BG44k, Gumout Regane all work fine)...and monitor it.

thanxz alot man i picked up some fuel injector cleaner (stp) and gonna see how it does.. im about to reset the cel now hope this fixes it but i will also look into the other things you both said when i go to the shop again.. thank you

 

[619rcr]

When you did the timing belt, was it yourself or a shop? Was the timing chked with a timing light? If its off enough, could cause lean code. Just something else to chk. Other causes for lean, vacuum leak, low fuel pressure or clogged injectors, map sensor reading incorrect.

If you have the capabilities some things to look for on a good scan tool are: Fuel trim & the time in msec the injectors are open and compare to specs. BTW A fuel trim reading in % would only be seen when reading in OBD2 generic protocol. Honda specific protocol does not show %. + or - 10% is about norm range for long and short. Long term is more of a trend of whats happening. If you are constantly lean you will see a postive #. STFT is constantly adjusting to whats happening now. When you get to about +20 on LTFT thats about the max the computer can adjust to max out the fuel injectors.