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  1. #1

    Default Tbi code 21 and 22 at the same time

    I have an 88 c1500 chevy with the 4.3l tbi. It has been excellent to me until recently.
    It started with random high idles. It wasnt constant. Every now and then id be at a light or something and it would suddenly rev up to around 1600-1800rpm. Id take off and notice that my 'shift' light would act funny. It would stay on when i wasnt in gear (its the 5 speed manual) and also stay on with my foot off of the gas while in gear. It didnt throw a code at all.
    Then it started throwing a code 21 at idle when it idled to high i checked the tps and it was working perfectly fine, around .48v to 5v or so, if i remember correctly and it was smooth increase and decrease.
    It drove fine for a few days.
    Then it started idling high much more ofter and stall while driving down the road in gear and i let off the gas. Thats when i got the code 22 as well as the code 21. Its stalling out now in gear whether or not im on the gas and idles high almost frequently. My check engine light goes on and off sporadically. Ive che ked the tps a few times now and still its where it should be.
    I have a feeling that its my ecu but i have now way to tell.
    Any ideas to what could be causing this?
    I rebuilt the throttle body about 3 months ago and replaced the old tps and ia. Along with new injector pod.
    Any help is much appreciated.
    Thanks
    Miguel

  2. #2

    Default

    Codes 21 and 22 mean your getting a reading that is to low voltage (code 22) and to high voltage (code 21) If you have a new TPS in it it could be a wiring issue or like you said a bad ECM. Do you get the code 12 reference code when you check for the lights? code 12 usually indicates that the ECM is normal and is what you should get for a code before any other ones. It's possible that your ecm is bad if your not getting the code 12. you may want to inspect the wiring harness portion for your TPS and make sure that there isn't a bad wire or plug. It's not very common to get both a high and low voltage reading like that if the TPS itself is bad. So it seems like it could be a resistance issue with the harness or ECM.
    1995 C1500 4.3L 2WD. JET TBI Spacer, JET stage 1 chip, 10mm Taylor custom wires, Pulstar Iridium Pulse Plugs.
    260k miles and still going strong...

  3. #3

    Default

    It did do the code 12 3 times like it should. I lowered the idle speed and it runs a whole pot better (i raised it abit before i rebuilt the tb). A guy mentioned that could be the problem as well. Im going to run the wires and check them this weekend.

  4. #4

    Default

    Well i ended up having to replace the fuel pump, ecu AND distributor because they all went bad at the same time.
    It drove beautiful for a day then i got the same code 21 and 22.
    The wiring was all good no voltage drops or anything at the ecu compared to the plug ln the sensor.
    Last thing i guess is to replace the tps again. Its less than 5 mo ths old. We will see what happens.

  5. #5
    Jr. Mechanic
    Join Date
    Apr 2013
    Location
    East Central Iowa
    Posts
    88

    Default

    One thing I have found is the coolant temp sensor can affect fuel delivery and idle quality and cause stalling. give it a check.

  6. #6

    Default

    It may also be possable that you have a slight intake or vacuume leak thats for some reason causing your computer to think its something to do with the TPS being bad.

    Just a thought..
    1995 C1500 4.3L 2WD. JET TBI Spacer, JET stage 1 chip, 10mm Taylor custom wires, Pulstar Iridium Pulse Plugs.
    260k miles and still going strong...

  7. #7

    Default

    Ive checked for vacuum leaks several times and theyre all good no leaks anywhere.
    I replaced the fuel pump, distributor and ecu.
    It ran fine for a few days then it quit working again.
    No spark or fuel. The pump is eorking because its gettimg to the throttle body. I figured it might have been the distributor so i replaced it again. Still nothing. I pulled the ecu and it had some burnt connections in the same place that my original ecu were burned at.
    I am at a loss to what this all could be...

  8. #8
    Jr. Mechanic
    Join Date
    Mar 2013
    Location
    adirondacks,n.y.
    Posts
    113

    Default

    try disconnecting the t.p.s. and test drive,see how it behaves,post back,so many sensers overide eachother,you might be looking in the wrong area

    - - - Updated - - -

    sorry,braincramp,are you right now ,no spark,but fuel?

  9. #9
    Jr. Mechanic
    Join Date
    Mar 2013
    Location
    adirondacks,n.y.
    Posts
    113

    Default

    im gonna need a translater for that one

  10. #10
    Jr. Apprentice
    Join Date
    Mar 2013
    Location
    Huntsville, alabama
    Posts
    18

    Default

    Translation: spam

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