Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

OBD 2 Computer Code Updated

Discussion in 'The Garage' started by ChevyHuny, Oct 10, 2002.

  1. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
    I was wondering if anyone could give me your thoughts on a computer code for my 96 pickup.

    First let me tell you what the problem was.

    When I would start my truck it would sometimes have no problems starting. One quick click and it turned on great. Other times I will turn it on and after it turns over it does a up and down revving thing. It would go above 1thousand back down to almost dieing and back up again. Like it is fighting with itself. Then it will level off and idle.

    Now when I put it in drive and push on the gas it chugs and clugs and it takes forever for it to get up to speed. To get it up hill from a slow speed (under 10MPH) I have to shift it into first. I can get up the hill but just barely in drive.

    So I'm on the road and I put it into drive and its doing its lovely chug clug help me I cant do this thing. BUT Once it gets above 10 MPH it acts like totally different truck. It is beautiful, runs like a charm has great pickup and go and its perfect. I was surprised actually. I didn't realize how much power a vortec has compared to my old truck. /forums/images/graemlins/eek.gif

    So I ran the codes on it and I get ONE code. Its
    P0102 : Power Train, Generic, Fuel and Air metering. Look in the book and it says: Generic Mass or Volume Air Flow Circuit Low Input
    Also my three monitors do not stop flashing like they are supposed to. O OH E = Oxygen sensor, Oxygen heat sensor and EGR.

    I have not looked in the book yet to see what the proper drive cycle is for my truck. I just tested it off, idle , and driving. Same codes and same monitors flashing.

    I have of course made sure everything on my engine is in working order. Everything is plugged in. New Cap and rotor, plug wires (i returned and bought another set just in case) plugs EGR valve, everything. It is timed right all the stuff you would normally check.

    So just wondering if anyone had any thoughts. I plan on going around and testing all of my sensors. Finding out the proper drive cycle and so forth still. Any thoughts anyways?
     
  2. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

    Joined:
    Dec 24, 2000
    Posts:
    2,690
    Likes Received:
    0
    Location:
    Bakersfield, CA
    Re: OBD 2 Computer Code

    Well, you mentioned o2 sensor. On my 96, I have an SES light currently on and the code I got was for my bank 2 #1 o2 sensor. But, I have no driveability problems like you. I wouldn't think your startup problem would be o2 sensor related. Anyway, guess I really didn't help too much... /forums/images/graemlins/crazy.gif
     
  3. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
    Re: OBD 2 Computer Code

    Yes it does, I thank you for your thoughts /forums/images/graemlins/smile.gif .It could be a combination of things so I am making a list and knocking them down. Ill add the O2 sensor to the list. /forums/images/graemlins/ears.gif
     
  4. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    P0102:
    Mass Air-Flow Sensor low.

    Given the trucks history, check the connection.
    Is it bad? Poor contacts? Spliced? Ect.
     
  5. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    </font><blockquote><font class="small">In reply to:</font><hr />
    I have an SES light currently on and the code I got was for my bank 2 #1 (Pre-cat) o2 sensor. But, I have no driveability problems

    [/ QUOTE ]

    Chances are, that that O2 sensor is worn/lazy. But it should be properly diagnosed first.

    Heres the catch, all the o2 sensors have worn evenly, it just-so happens that "bank 2, sensor 1" was the first to fall out of spec. If that sensor is replaced, it (a new sensor) might throw the "graded-curve" out of sync', then tossing the other or some of the other O2 sensor flags up.

    Do not be suprized to find another code flagged after the orignal code was repaird. (in this case)
     
  6. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

    Joined:
    Dec 24, 2000
    Posts:
    2,690
    Likes Received:
    0
    Location:
    Bakersfield, CA
    Re: OBD 2 Computer Code

    Grrr, why did you have to go and tell me that /forums/images/graemlins/crazy.gif. I was going to go buy a new sensor tomorrow for it, it's throwing my fuel delivery on that bank way off and making it run extremely rich. So it's possible I will need to replace all 4 90 dollar sensors? /forums/images/graemlins/shocked.gif
     
  7. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    Re: OBD 2 Computer Code

    I agree with Twizted. Sounds like a Mass air flow sensor problem to me. I would check there first.

    /forums/images/graemlins/smile.gifBe sure to put your Tin Foil cap on before doing any more tests /forums/images/graemlins/laugh.gif
     
  8. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    </font><blockquote><font class="small">In reply to:</font><hr />
    So it's possible I will need to replace all 4 90 dollar sensors?

    [/ QUOTE ]

    Nah, possible but not very likely.
    One or two, maybe. But I have found they rarly need all four replced.

    Just don't be suprized to find another code pop up, sooner or later. It might not "pop another code" at all - who knows.

    Usualy, I map-out the sensor out-puts and reccomend replaceing the two "lazy" ones. I've had pretty good luck with that procedure.

    If you do not have the ability to see and "map" the O2 sensor out-puts, just replace the one you know is bad.


    By The Way:
    I do not recomend "replaceing parts" without the proper diagnistics completed first, But this is the internet, and my reply is "a best guess" based on what has been said.
    Take it for what it's worth.
     
  9. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    </font><blockquote><font class="small">In reply to:</font><hr />
    Be sure to put your Tin Foil cap on before doing any more tests

    [/ QUOTE ]

    Step one: Dissconnect Neg. Battery Cable.
    Step Two: Obtain Static-Electrisity Eliminator Cap (SEEC) and install (useing manufatures reccomendations)
    Step Three: Contiunue dignostic proccedures as per published service manuals
     
  10. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
    Re: OBD 2 Computer Code

    </font><blockquote><font class="small">In reply to:</font><hr />
    I agree with Twizted. Sounds like a Mass air flow sensor problem to me. I would check there first.


    [/ QUOTE ]
    Could that also cause the monitors to continue to flash. (In the book it says they need to stop flashing or there is a problem).

    </font><blockquote><font class="small">In reply to:</font><hr />
    Be sure to put your Tin Foil cap on before doing any more tests

    [/ QUOTE ]

    See there is a another problem. Where does one find a high quality hat such as that. I do not think I could afford anything as good as the one Twiz has.
     
  11. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    Monitors? The SES light?
     
  12. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
  13. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
    Re: OBD 2 Computer Code

    I don't know if they are the same as the light you are talking about.

    I guess my vehicle supports only 3 of the monitors but they are not supposed to be flashing as flashing "indicates that the vehicle supports the associated Monitor, but the Monitor has not yet run its diagnostic testing".

    Why it is doing that puzzles me. Maybe I am not running the drive cycle right? Or maybe due to the bad sensor (which the code indicates) it is unable to run its drive cycle and those monitors are unable to run their diagnostic tests?
     
  14. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    Ahhh, looks like your talking about setting the I.M. flags.
    "Monitor" might be genneric trem that they use to discrib the same thing.
    Are you tring to get a emissions test done? Is that why you are doing "drive cycles"?

    </font><blockquote><font class="small">In reply to:</font><hr />
    maybe due to the bad sensor (which the code indicates) it is unable to run its drive cycle and those monitors are unable to run their diagnostic tests?

    [/ QUOTE ]

    BINGO!!
     
  15. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
    Re: OBD 2 Computer Code

    Well the reason why I am running the computer codes is becuase of the way it is driving. If I drive around the way it is now I will get into a accident. If I needed to get out of someones way forget it. When I take off from a stop it takes forver to get up to 10mph. So I ran the codes and that is what it gave me.

    I have never used a computer scanner before. I am definatly not good at this kind of stuff so I am just making a guess at what it could be by what it gave me. I have not tried to run emissions yet or register it becuase of the way it runs.

    I will try to find something that can help me splain drive cycles. Again I am not good with this sort of stuff lol. I am a newbie.

    I think I will try to test that sensor. It is funny becuase the mass air flow sensor is a square sensor that just sits on the intake air box. I never thought that silly thing would make my truck run like it does. OH and I wil make sure to wear my hat before I do anything. /forums/images/graemlins/ears.gif
     
  16. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
    Re: OBD 2 Computer Code

    I figured it out /forums/images/graemlins/ooo.gif

    My monitors are flashing because they are unable to complete their diagnostic tests. I thought it was because of the mass air flow sensor but its not. They flash because I have not put my truck through the proper OBD II drive cycle. I guess flashing does not mean a fail in a sensor but just that the monitor has not completed its test (again because I have not put it through the proper drive cycle). If I have a failer in a sensor that the monitor is testing it will stop flashing (indicating it has completed its test) and give me the code for that said sensor. DUH MANDY /forums/images/graemlins/rolleyes.gif

    So it tells me to look in my service manual for the proper OBD II drive cycle. Not a warm up cycle, not a TRIP Dive cycle but a OBD II drive cycle. So I look in my book and it talks about my code reader but nothing about how to do a proper drive cycle.

    It is all very simple if I would just do my homework like I should /forums/images/graemlins/tongue.gif . LOL So now I have to find what the proper OBD II drive cycle is for my specific truck. Then I can run the codes and get a proper diagnostics for the whole thing.
     
  17. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    Well, you have succeed in completely confuseing me. (which isn't very hard to do, lemme' tall ya' /forums/images/graemlins/wink.gif)

    If it's a OBD drive cycle you want than a OBD drive cycle you shall get.


    1 - Start the truck, dead-cold. Early in the morning is best.
    The intake air temp, and engine coolant temp must be with in about 20 degrees of each other. Let the engine idle in park, until it reaches opperating temps (about 180 deg.)
    This will/should set the HO2 flag (oxygen sensor heater) and the AIR flag, if so equipped. It will also check for miss-fires during this portion, as-well as through-out the remainder of the Drive Cycle.

    2 - Excelorate up to 50 MPH (less than 60, but over 45). DO NOT applie more than 3/4 throttle while excelorating. Maintain this speed for aproxmitaly 1 to 3 miles, with minmal throttle adjustement.
    This may set the EVAP flag, and will also pre-heat the converter, prepareing it for the next self-test.

    3 - Decell to a stop, with minmal brake application. Use the engine to slow you down. Come to a full stop and stay "parked" for aprox. 1 to 3 min. DO NOT put the transmission in park, keep it in Drive with the brakes appied.
    This will complete the Converter self test.

    4 - Excelorate up to about 40 MPH. Again, useing no-more than 3/4 throttle input and maintain this speed for about a mile (shouldn't take that long, tho').
    This will/should set the O2 sensor flags.

    5 - Decell to a stop, useing minamal brake application. Stay at a stop for a about as long as a stop-light takes to turn green, then excellorate to about 40.
    This may set the EGR flag, if it has not all-ready been set. It will also give the vehical a seccond chance to run the O2 sensor self-test.

    6 - Excell/Cruise/Decell, from aprox 30 to 40 and back to 30, useing minamal throttle input and brake application to change the vehical speeds. This may set the EGR flag, if it has not been set, as-well as O2 sensor flag, if it has not been set yet.

    I have addopted the above Drive Cycle to fit my local area, and it will set ALL six of the possible OBDII self-tests, if all six are required. Except:
    - Sometimes the EVAP test will not run, sometimes "free-way" speeds are not quite long enough to run the EVAP system Self-Test. Not a big deal as meny vehicals now have a "forced" EVAP system test.
    - If a OBDII Self-Test catigory is "border-line", the computer may take longer to detirmin if the system passes/fails the test. For example, if a O2 sensors out-put was slow to react. The computer may run the test, but was unable to detirmin if it "passed or failed" and therefore require another Drive-Cycle.
    - If the SES (service Engine Soon) light is on.

    By the way, a OBD drive cycle will not "fix" anything, if thats where you are going with this. ?
     
  18. ChevyHuny

    ChevyHuny 1/2 ton status

    Joined:
    Aug 17, 2001
    Posts:
    2,279
    Likes Received:
    0
    Location:
    Washington State
    Re: OBD 2 Computer Code

    </font><blockquote><font class="small">In reply to:</font><hr />
    I have addopted the above Drive Cycle to fit my local area, and it will set ALL six of the possible OBDII self-tests, if all six are required.


    [/ QUOTE ]

    If by "self tests" you mean the Monitors OBD II has 11. Not all vehicles have 11. Like mine only has 3 of them. I

    Ill type the definition it gives me for Monitors and you tell me if its what you are talking about. Sorry I am not too good at this stuff lol. So you tell me if these monitors are the same as "self tests" Okay?

    The diagnositic program inside the on board computer contains several poicedures and diagnostic strategies. Each procedure or diagnostic strategy is designed to monitor the operation of and run tests on specific emissions related componant to ensure the the system is operating correctly. On OBD II systems these procedures and diagnostic strategies are called MONITORS. A maximum of 11 monitors are utilized in OBD II systems. Not all vehicles use all 11 monitors. My truck only uses 3 of them.
    Read about them here

    Now this is where my flashing monitor problem I have been telling you about comes in.

    When a monitors Trip Drive Cycle is performed properly the monitor icon on the code reader will change from FLASHING to a SOLID condition indicating that the monitor has run and completed its diagnostic testing.
    Mine are flashing, therefore I need to run the proper drive cycle in order for them to do thier self tests.

    It seems that after 96 all vehicles can only use a OBD II Scanner which from what I have read so far has allot more self tests with emission then the previous vehicles.

    I hope that clears it up.
    The OBD II CODE READER website has a little info but if you download the manual it is easier to understand.
    I did not read the manual fully so I got very confused. Duh me lol.


    </font><blockquote><font class="small">In reply to:</font><hr />
    By the way, a OBD drive cycle will not "fix" anything, if thats where you are going with this. ?


    [/ QUOTE ]

    Oh I know /forums/images/graemlins/smile.gif

    I will try your drive cycle and see if it allows my monitors to complete thier test . Thank you so much for typing all of that out for me. I have been unable to find the proper drive cycle I need to run. The book just tells me to look in my service manual. I did that and it is not in there so I will use what you gave me. Thank you soooooo much. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
     
  19. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    I see... We are talking about the samething.
    That Code Scaner operates differently than the Tech2 I use.
    It would appear as though they tried to combine a DTC list and the I/M monitors list (or "Flags") on one screan or as one operation. (kind of an odd way to do it, but it'll work, I guess)

    There might be 11 monitors, but some of those don't exsist currently. As I have never seen a "A.C. system preformance" monitor, or a "fuel system" monitor. Both of which will/can have their own DTCs, but as of yet.. are not part of the OBDII system performance tests.

    O.K, now that we are on the same page:
    The OBDII monitors are designed to complete their self-tests during normal driveing, and they will continue to complete self-tests, even if the moniters are all-ready set.
    A OBDII drive cycle can help "kick-start" the procces. It is usefull if the Codes have been cleared after repairs, and someone wants to check the preformance of a system, or for setting up the Monitors for Emissions testing.

    Now,
    What is it you are tring to do? Why are you tring to get all of the monitors to trip? Is there a problem?
    Is the SES (Service Engine Soon) light on now?
    If so, What is the DTC?
     
  20. Twiz

    Twiz 1/2 ton status

    Joined:
    Mar 8, 2001
    Posts:
    3,729
    Likes Received:
    0
    Location:
    Clearfield Ut.
    Re: OBD 2 Computer Code

    I reared the post, (disregard the above reply)

    It looks like you are still stuck with the same P0102 code, the Mass Air-Flow sensor problem.

    Have you checked the conections? Is the wireing spliced?


    Hold on a sec and I'll see if I can find a diagnostic trouble shooting tree for that code.
     

Share This Page