HELP! System Running Too Lean and Fuel Trim Code.
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Joined: Jun 2022
Posts: 38
Likes: 10
From: Moraga, CA
I am curious as well but it looks like we are unlucky. I have a P0171 that appears randomly and then goes away eventually. It makes OBD read for smog in California difficult.
I have replaced oxygen sensors, spark plugs, and performed the troubleshooting procedure in there repair manual with no success in finding a problem. This includes checking EVAP, fuel pressure, and valve clearances.
I have replaced oxygen sensors, spark plugs, and performed the troubleshooting procedure in there repair manual with no success in finding a problem. This includes checking EVAP, fuel pressure, and valve clearances.
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Joined: Sep 2022
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From: McAllen
Sorry to revie al old thread, but ive been battling this same issue with P0170 and P0171 for the past few months and hasnt gone away.
Just wanting to see if there was a fix to this thread.
Ive replaced what OP has already mentioned. Im bummed out now
Just wanting to see if there was a fix to this thread.
Ive replaced what OP has already mentioned. Im bummed out now
Registered User
Joined: Jun 2022
Posts: 38
Likes: 10
From: Moraga, CA
Unfortunately I have not found a solution yet. I did everything the Honda manual tells me to check and everything was as it should be. I'll update here if I ever find out the solution. I just hope the check engine light stays away whenever I need a smog check.
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Joined: Sep 2022
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From: McAllen
Yea, I’ll update here as well.
so far I’ve replaced:
-fuel injectors with OEM
-fuel pressure regulator with OEM
-low mileage OEM fuel pump and sock/strainer
-valve adjustment
-spark plugs with ngk
- denso upstream and downstream Oxygen sensors.
-MAP has the zip tie on it
code still comes up.
so far I’ve replaced:
-fuel injectors with OEM
-fuel pressure regulator with OEM
-low mileage OEM fuel pump and sock/strainer
-valve adjustment
-spark plugs with ngk
- denso upstream and downstream Oxygen sensors.
-MAP has the zip tie on it
code still comes up.
Joined: Jul 2013
Posts: 5,736
Likes: 633
I really appreciate your assistance Deckoz as I've been literally stressing out so much trying to troubleshoot this before smog test :`( Knowing this is more towards fuel related, I too was suspecting the mentioned possibilities you've stated above.
- New injectors are "OEM" injectors as the stock injectors are from Kei-hin..or at least I hope they're OEM..
- New map sensor and tie wrap was bought from Honda directly
- New Primary o2 sensor is Denso 234-4124. Purchased this as it says it will fit the s2k. Possibly wrong o2?
- Stock FPR seems like its losing pressure when vacuum attached. When I unplug vac line from manifold, idle increases. Possible collapsed vac line or bad FPR?
- New injectors are "OEM" injectors as the stock injectors are from Kei-hin..or at least I hope they're OEM..
- New map sensor and tie wrap was bought from Honda directly
- New Primary o2 sensor is Denso 234-4124. Purchased this as it says it will fit the s2k. Possibly wrong o2?
- Stock FPR seems like its losing pressure when vacuum attached. When I unplug vac line from manifold, idle increases. Possible collapsed vac line or bad FPR?
Registered User
Joined: Jun 2022
Posts: 38
Likes: 10
From: Moraga, CA
Yea, I’ll update here as well.
so far I’ve replaced:
-fuel injectors with OEM
-fuel pressure regulator with OEM
-low mileage OEM fuel pump and sock/strainer
-valve adjustment
-spark plugs with ngk
- denso upstream and downstream Oxygen sensors.
-MAP has the zip tie on it
code still comes up.
so far I’ve replaced:
-fuel injectors with OEM
-fuel pressure regulator with OEM
-low mileage OEM fuel pump and sock/strainer
-valve adjustment
-spark plugs with ngk
- denso upstream and downstream Oxygen sensors.
-MAP has the zip tie on it
code still comes up.
Registered User
Joined: Sep 2022
Posts: 4
Likes: 0
From: McAllen
Saw that my LTFT AND STFT were all high, which I believe indicates it’s gotta be a leak of some sort somewhere.
I’ll get it smoke tested as well.
it’s been frustrating.
but I’ll also double check my work with the injectors. I don’t see any leaking from them, but I’ll try switch them out with the old and see if they’re bad. They were OEM new but I did notice the car perform worse after I changed the injectors.
I’ll get it smoke tested as well.
it’s been frustrating.
but I’ll also double check my work with the injectors. I don’t see any leaking from them, but I’ll try switch them out with the old and see if they’re bad. They were OEM new but I did notice the car perform worse after I changed the injectors.
Registered User
Joined: Jun 2022
Posts: 38
Likes: 10
From: Moraga, CA
The car runs fine and has no drivability issues. The check engine code simply comes and goes. If it were a relay issue, I imagine the problem would be more pronounced such as the car not running. But I am not a real mechanic, just a shade tree mechanic.
Registered User
Joined: Jul 2023
Posts: 203
Likes: 95
Got any data streams?
I'm just as shadetree as you, but I'll try to get a datastream from my car this weekend...
Kinda curious what the values are for
A/F sensor (1)
MAP sensor
A/F sensor heater
Short and Long term fuel trims
(also add some gas and see if long term fuel trims drop)
Ideally, if you have a graphing software, that'd be even better.
Also, could you take a look at the PCV system if that's sealing correctly? Maybe you've already replaced the valve, but these kinda go bad on AP1s.
I'm just as shadetree as you, but I'll try to get a datastream from my car this weekend...
Kinda curious what the values are for
A/F sensor (1)
MAP sensor
A/F sensor heater
Short and Long term fuel trims
(also add some gas and see if long term fuel trims drop)
Ideally, if you have a graphing software, that'd be even better.
Also, could you take a look at the PCV system if that's sealing correctly? Maybe you've already replaced the valve, but these kinda go bad on AP1s.
Last edited by bad_driver; Jun 17, 2024 at 05:51 PM.