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Thread: OBD Code P1171- what does it mean?

  1. #1
    Join Date
    Apr 2004
    Location
    Wake Forest, NC
    Posts
    53

    Default OBD Code P1171- what does it mean?

    I just pulled a P1171. The conversion chart says: Long Term Fuel Trim.

    I have no idea what that is or where to start looking for the problem. Any suggestions would be greatly appreciated.

    Also, I about a third of the way through a 1500 mile trip, can I wait to get home before repairing.

    Thanks,
    Joel
    2000 V70 XC, 2003 Nissan 350Z, 1996 Saab 900S

  2. #2
    Join Date
    Nov 2004
    Posts
    180

    Default P1171

    Quote Originally Posted by ncst8wuf
    I just pulled a P1171. The conversion chart says: Long Term Fuel Trim.

    I have no idea what that is or where to start looking for the problem. Any suggestions would be greatly appreciated.

    Also, I about a third of the way through a 1500 mile trip, can I wait to get home before repairing.

    Thanks,
    Joel
    Here is what alldata says,

    Condition
    The control module receives information from the heated oxygen sensor (HO2S) about the fuel/air mixture when idling at both the lower and upper part-load range - If the fuel/air mixture deviates from [lambda]=1 the short-term fuel trim will compensate for this by adjusting injection time so that [lambda]=1 is achieved. When the short-term fuel trim makes an adjustment, the integrator median must be adjusted by the long-term trim. Diagnostic trouble code (DTC) ECM-261A will be stored when the long-term trim must be adjusted to maximum in the lower part of the load area.

    Condition
    none

    Possible source

    Upper limit:

    * intake air leakage
    * exhaust system air leakage
    * low fuel pressure

    Lower limit:

    * intake air leakage
    * high fuel pressure
    * leaking injectors
    * defective mass air flow (MAF) sensor
    * contaminated engine oil
    * oil level too high

    Condition

    * none

  3. #3
    Join Date
    Apr 2004
    Location
    Wake Forest, NC
    Posts
    53

    Default

    Don,

    Thanks for the information.

    My CEL has been coming on and off over the past week or so. I assume this is the error code triggering the light. Which one of the symptoms stated would cause this fluctuation?

    If it was some sort of air leakage, how can I trouble shoot?

    Thanks again,
    Joel
    2000 V70 XC, 2003 Nissan 350Z, 1996 Saab 900S

  4. #4
    Join Date
    Nov 2004
    Posts
    180

    Default Don't know

    Quote Originally Posted by ncst8wuf
    Don,

    If it was some sort of air leakage, how can I trouble shoot?

    Thanks again,
    Joel
    All I know is what I read in the file.
    But chack hose clamps, listen for a hiss, wiggle some hoses.
    Last year my '89 was running very badly. The mechanic found a dime size hole in the hose between the air mass meter and the turbo. It was on the underside so I could not see it.

    Don

  5. #5
    Join Date
    Nov 2012
    Location
    New Mexico
    Posts
    2

    Default Dirty Intake??

    Quote Originally Posted by ncst8wuf View Post
    I just pulled a P1171. The conversion chart says: Long Term Fuel Trim.

    I have no idea what that is or where to start looking for the problem. Any suggestions would be greatly appreciated.

    Also, I about a third of the way through a 1500 mile trip, can I wait to get home before repairing.

    Thanks,
    Joel
    Hi Joel,

    Our senior has given you a great technical answer. If I could simplify, Yes, you can most probably make it home. When you get there, (providing the above items check out) you may want to do some type of induction system cleaning. Long term fuel trim (depending on altitude where you are) is a way of measuring a dirty intake system. I'm in New Mexico and at an elevation of around 5,000 ft. above sea level. Simply put, if you use a OBD scan tool that can read live data, check long term fuel trim and any reading above 2.0% positive, you have a dirty intake system. After a cleaning, your long term fuel trim of (LTFT) should be 0.00% or in the negative. Whatever service you go with, keep in mind that some milage (approximately 20 miles or so) will need to be driven in order to be sure that the chemicals from the service have been consumed before an accurate new LTFT reading can be achieved.
    If you would like a suggestion, BG products has a 3 part cleaning service that is quite effective. It consists of 2 cans induction cleaner (part #206)fogged into the engine as the air flows.This requires a specail tool. and 1 can 44k (part #208) to pour into fuel tank. In order to find a service professional near you that offers this service, You can go to BGfindashop.com, enter in your zip code and look for shops,Dealerships,etc. that have fuel products listed.

    Whatever service you end up using, remember, you can check to results of their effectiveness by the LTFT results. The larger the reducion in LTFT, the more the system was cleaned.
    Hope this was helpful.
    SB

  6. #6
    Join Date
    Apr 2003
    Location
    Devon PA
    Posts
    9,484

    Default

    You do realize this thread is from 2005 and I would guess he has made it home already in SEVEN YEARS or has sold the XC by now.....
    As for your BG, a simple $10 Seafoam will do the same and works quite well on Volvos..
    Shameful post
    Email: jrl1194(at)aol.com
    If the subject is car purchase related please use jrl1194(at)gmail.com
    2006 XC70 White/Black 58K miles, new daily driver
    2000 V70R wife's. Won't sell, now 120K miles and still perfect
    1994 Lincoln Continental. In concours condition with low miles.

  7. #7
    Join Date
    Nov 2012
    Location
    New Mexico
    Posts
    2

    Default

    Shameful Post??
    I'm new to this site and I'm not sure how my suggestions were "shameful" when I was merely trying to help with a different approach I might add you didn't include with Seafoam or any other product. If this is how you respond to suggestions from new members I really can't imagine the member base being very large. And you won't need to worry your judgemental self about hearing from me again. BTW, If it was so old for discussion, why was it available to read? And How do you know (if indeed the XC was sold) the person that bought it wouldn't benefit from my suggestion? You just keep with your "one-product-fits-all" Good luck with that. The proof is in the LTFT.

  8. #8
    Join Date
    Apr 2003
    Location
    Devon PA
    Posts
    9,484

    Default

    One product fits all, who said so?
    (BG products are overpriced for one thing) and he didn't ask for a product to clean the MAF or anything else.
    All this poster did from eons ago was to ask what to do.
    PO1171 is usually a bad MAF
    Cleaning THESE MAFS usually does more harm than good. When the go, they go.
    Up to 98 they're easier to clean but the ones for the ME7 engines not so much.
    Last edited by JRL; 11-26-2012 at 01:02 PM.
    Email: jrl1194(at)aol.com
    If the subject is car purchase related please use jrl1194(at)gmail.com
    2006 XC70 White/Black 58K miles, new daily driver
    2000 V70R wife's. Won't sell, now 120K miles and still perfect
    1994 Lincoln Continental. In concours condition with low miles.

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