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bad gas mileage MAF? IAC?

Discussion in '1st Gen. Tacomas (1995-2004)' started by drf1, Apr 2, 2022.

  1. Apr 2, 2022 at 10:31 AM
    #1
    drf1

    drf1 [OP] Member

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    I have been reading through all these threads on maintenance, I'm sure this has been discussed many many times. just figured it would be easier for me to post my own thread. hoping all the real mechanics will see it. SO i have 1999 taco tacoma, has 350,000k. head gasket blew out. Had it repaired. they put in a new radiator also and new fuel filter. my problem is the truck now idles at 1100 rpm and has 15 MPG. I drive the truck from Arizona to FL. got 25 mpg at 70 mph. now im at 15 mpg. I did remove the air idle controller and cleaned the throttle body. but I'm not really a mechanic, so i don't know how to test stuff. some things i read on here are not EZ to understand. AIC i understand as air idle controller. MAF? and there was one other thing you all mention alot, but i don't know the abbreviation... i did buy a scanner but the truck has no codes. the scanner does live data but im not sure what im reading...I did have to buy a new battery, so it was unhooked for 2 days....if anyone can help me find the best links to read i would be very grateful. any questions i can answer.
     
  2. Apr 2, 2022 at 10:44 AM
    #2
    KdF

    KdF Old Rednek Type

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    East-ByGod-TEXAS!
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    I got 14 last fill up, and it sits for a while between fillups. I believe it's the gas. Too much ethanol. I have NEVER gotten 25 mpg in my truck. 18 tops.
     
    straightawaykid likes this.
  3. Apr 2, 2022 at 10:50 AM
    #3
    Wsidr1

    Wsidr1 Well-Known Member

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    MAF= mass air flow sensor. Its in the air intake tube between your air filter and the throttle body. It has a two wire connector coming off it.

    It senses how much air is entering and modulates the fuel volume. It has a tiny wire filament that can get dust and dirt on it and cause the resistance value to change, thereby giving the computer bad data.

    If you take it out (very easy to do), it is fragile. And, only spray clean it with MAF Sensor Cleaner. Do not use any other spray,m and definitely don't touch the wire inside.
     
    drf1[QUOTED][OP] likes this.
  4. Apr 2, 2022 at 10:51 AM
    #4
    Wsidr1

    Wsidr1 Well-Known Member

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    BTW any auto parts store sells MAF cleaner.
     
  5. Apr 2, 2022 at 10:54 AM
    #5
    Wsidr1

    Wsidr1 Well-Known Member

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    upload_2022-4-2_12-54-3.jpg

    This is for a 2000 model, but they are all in the same location.
     
    drf1[OP] likes this.
  6. Apr 2, 2022 at 3:32 PM
    #6
    drf1

    drf1 [OP] Member

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    OK GREAT i will have a look for that MAF, this tocoma is 4 cyl. 2.7 thats why i should get 20-25. isn't there another sensor that also controls air/fuel mixture? i thought i read about 3 separate ones. or what else should i be looking to clean.
     
  7. Apr 2, 2022 at 3:36 PM
    #7
    drf1

    drf1 [OP] Member

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    where can i download that manual?
     
  8. Apr 4, 2022 at 6:07 AM
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    Wsidr1

    Wsidr1 Well-Known Member

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    I sent you a link in a PM. File size is too large to upload to this site.
     
  9. Apr 4, 2022 at 6:19 AM
    #9
    CrippledOldMan

    CrippledOldMan Well-Known Member

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    I just changed my plugs and wires on a 03 DC V6. so far it's made a huge improvement in my mpg. when was the last time you installed new plugs and wires. I did this after cleaning my MAF and the Throttle Body. After disconnecting the battery, the truck will have to relearn your driving habits. Might take a tank of gas to return to normal. Just my 2 cents worth.
     
    drf1[OP] likes this.
  10. Apr 4, 2022 at 6:19 AM
    #10
    96BlueTacos

    96BlueTacos トヨダ

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    fwiw, my V6 automatic supercharged 2001 gets like 20-21 mpg, 190,000 miles (I can push 25-26 mpg on the highway drives from Denver to boulder)

    my V6 Manual non-charged 1996 gets like 17.5 now 383,000 miles, I used to get 19 mpg and if I tried really hard with driving habits, I used to get 20. Gas blends change seasonally and can definitely loose you some mileage.

    I always hear the 4 cyls are even better with gas so, 15 mpg sounds like you have definitely something that is not tuned up.
     
  11. Apr 4, 2022 at 6:30 AM
    #11
    Black DOG Lila

    Black DOG Lila Well-Known Member

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    Stock. EZ pass.Dump pass.Inspection sticker.Convict printed lic.plates.FG cap.
    Your 1999 2.7L doesn't have an air/fuel sensor, those came later.
    You have 2- O2 sensors.
     
  12. Jun 10, 2022 at 12:39 PM
    #12
    brians356

    brians356 Active Member

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    Let's start at the other end: How often should wires (not plugs) be changed? I have an '03 and almost certainly the OEM SP wires.

    (My Xtra cab 2.7 5-dp 4x4 gets about 19-20 mpg around town, and up to 24.7 on long highway trips ... depending on weather, altitude, and terrain.)
    -
     
  13. Jun 10, 2022 at 2:50 PM
    #13
    jbrandt

    jbrandt Made you look

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    @drf1 How long has it been since you had the battery reconnected?

    All the emissions readiness sensors get reset and need to be re-calibrated (usually requires a specific set of driving conditions). All things equal, that could account for a loss in efficiency.

    Use your scanner to check for emissions readiness to at least rule that out...

    Also be honest with what driving you are comparing. A 1000+ mile all highway road trip is a lot different from a commute. You need to verify over multiple tanks and apples to apples.
     

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