Air/Fuel Learning 1 help
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This is a discussion on Air/Fuel Learning 1 help within the Tuning: Electronic Engine Management forums, part of the Tech & Modifying & General Repairs category; So a few weeks back I noticed my a/f learning 1 has been about -9 lately when cruising. in the ...

  1. #1
    Registered User tesla317's Avatar
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    Air/Fuel Learning 1 help

    So a few weeks back I noticed my a/f learning 1 has been about -9 lately when cruising. in the past it's always been within 0 and -2. When under load it is around -5 but still drops to -9 when cruising.

    I'm afraid it may be running lean. I haven't done anything different to the intake system, my car is a 2010 WRX, Cobb stage 2. Also, the only thing that happen a few months back was it threw a code when I was getting it coming up a mountain, it said turbo solenoid. I reflashed map and has been fine, the only thing noticeable is the A/F learning 1 is different.

    Any help or insight would be appreciated.

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    Car is "old" 5 years of air going through it. Get some mass air flow cleaner on the MAF sensor and see what happens, also check the air filter. This will be the two easiest things to do. I have also seen the turbo solenoid code and it is usually a mistake within the car to throw the code. If it goes away and stays away, check codes with AP then you are fine. -5 under load is just within the acceptable range, -9 however at cruise is not. Acceptable with cruise is + / - 8%. If the two above "fixes" do not work, I would start looking into a boost leak somewhere, and make sure all of your hoses are tight. You are at stage 2 so you have an upgraded air filter, make sure it has not become loose throughout all of the connections. Check the intercooler piping, and as always check the BPV (which is horrible on these cars).

    If these do not fix the problem do some data logs in 3rd gear 2500-redline. You can post them on here and/or send them to Cobb and they may be able to give you more insight. Usually Cobb tells you to bring it to a protuner though because they do not have the car in front of them and do not want to be responsible for you doing something that a company told you to do without having the car in front of them.

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    Registered User tesla317's Avatar
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    No I have the stock filter which is recommended for Cobb's map. I checked the filter is fairly new, and I cleaned the MAF sensor last year. I still will anyways. I'll do a pull and post it tomorrow. I checked my hoses, everything seems secure. To be honest I'm not exactly sure how to check for a boost leak. I do reach full target boost by the way.

    oh and during idle it is -11.72 :/ when I coast in gear it is -1. Under acceleration -7. Light throttle cruising -10.
    Last edited by tesla317; 02-15-2015 at 02:05 PM.

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    Registered User nsibanez's Avatar
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    So it's taking fuel away meaning you're running rich?
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    Master Baiter EJ257's Avatar
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    Have you replaced front O2 sensor?


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  7. #6
    Registered User tesla317's Avatar
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    I assume that's what it means, but it's not running hot that I know of...if it would if it was running lean.

    No I haven't changed the front O2 sensor. Is it somewhat easy to get to?

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    Those numbers are low should taper down to 11.7 not already be there. Take a data log, and to check for s boost leak we will be able to look at TD boost error. And yes you are running rich.
    Last edited by ryager; 02-16-2015 at 01:00 PM.

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    Registered User nsibanez's Avatar
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    The front o2 sensor is very very easy. Jack the car up, take off the left front wheel, move the plastic shield out of the way and it's right there in the header. Takes all of 5 minutes
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    Master Baiter EJ257's Avatar
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    Your issue could be a few things:
    1) Leak.
    2) Bad/dirty MAF sensor. You just cleaned it, but if you have a local that you can swap MAFs with for an hour or so, you could easily rule that out.
    3) Failing O2 sensor. I don't know how many miles are on the car, but the front O2 sensor could be "off" without necessarily throwing a code.
    4) Change in fuel blend. Depending on your location, you could face summer/winter blends of fuel.
    5) Bad MAF scaling.
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    Registered User tesla317's Avatar
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    My car has about 39,000 miles on it. I'll clean the MAF when the weather permits. And I have been using the same fuel from the same place, but I'll fill up somewhere else to rule that out as well.

    As of right now will it harm the engine? Most of the time when in gear is -7 and below, just the idle and light cruising that get above -8. I plan on figuring this out asap, but it may take a few weeks due to work schedule and the current weather.

    Thanks guys

  12. #11
    Master Baiter EJ257's Avatar
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    Quote Originally Posted by tesla317
    My car has about 39,000 miles on it. I'll clean the MAF when the weather permits. And I have been using the same fuel from the same place, but I'll fill up somewhere else to rule that out as well.

    As of right now will it harm the engine? Most of the time when in gear is -7 and below, just the idle and light cruising that get above -8. I plan on figuring this out asap, but it may take a few weeks due to work schedule and the current weather.

    Thanks guys
    Your AFR Learning isn't pegged, so it's forever changing (that's a good thing). Datalogs are the only way to determine if it's harmful or not.

    Same gas, same station...doesn't really matter when they are only providing you what they are getting from their supplier. Again, depending on your location, the summer/winter blend could vary drastically (E85 in my area is often ~E70 in the winter).
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    If you live in a cold environment, and no I am not joking, check the exhaust and make sure it is not clogged. Smell for exhaust when you are driving around and see if snow is getting into your exhaust and clogging it, which will in turn make your car run rich. This is one of the easiest things I can think of doing first, that and MAF cleaning along with making sure the intake is clean. Then you have to start checking o2 sensor and fuel injectors.

  14. #13
    Registered User tesla317's Avatar
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    So I decided to fill up at a different station who advertises no ethanol. Then I cleaned my MAF sensor, and at it seemed to improve significantly.

    Idle -5

    Cruising -1.5

    Coasting in gear 0

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    Those numbers are within the adequate range

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