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3800 Series III Limp Mode issue 08 Buick Lacrosse

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  • #516247
    Vlad2Vlad2
    Participant

      So I got the suspension on my buick all back together and took it out for a run. Now it has a new problem.

      When it is in traffic, and the engine is hot it goes into limp mode, it bucks and I have zero throttle response. It will give me a little throttle here and there, just enough to get it off the road. When this happens, it throws 2 codes (cheap code reader, best investment ever), It throws P0068 and U0107 (when this happened the first time I got code P2108 but changing the battery stopped that code).

      Here is what I know so far:

      1. The engine has to be hot for it to occur, I was driving to a friends and it was fine, I got gas and drive 1/8th mile and it started in traffic, pulled off and turned it off, let it sit and it fired right up and was fine. Got to the friends, chilled for 10 min and went out to eat, started it and it went right to limp mode. Came back after dinner (they drove), it was fine.

      2. I disconnected the MAF sensor and it still started right into limp mode (so I don’t think it is the MAF).

      This car is drive-by-wire, so could it be something with the throttle body or Throttle Positioning Sensor?

      This is a puzzle and I don’t want to start throwing sensors at it, any ideas on this would be great.

      Thanks!

    Viewing 10 replies - 1 through 10 (of 10 total)
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    • #516265
      college mancollege man
      Moderator
        #516267
        Vlad2Vlad2
        Participant

          Thanks College man, but I have read those already. I am not sure which part I should start at is I guess what I am asking.

          P0068 BUICK
          – Air leak between the MAF sensor and throttle body – checked this and it is fine
          – Dirty Throttle body or Mass Air Flow (MAF) sensor – cleaned it when I swapped the battery last weekend with CRC MAF cleaner
          – Throttle Position (TP) sensor not seated properly – need to check this
          – Faulty Throttle Position (TP) sensor – need to check
          – Faulty Mass Air Flow (MAF) sensor – pulled this and started it and it was doing the same thing, so this isn’t it.

          U0107 BUICK
          – Faulty Throttle Actuator Control (TAC) module – this seems to have many parts to it, just not one module, I could be wrong (I am a network sec. admin, not a mechanic 🙂 )
          – Throttle Actuator Control (TAC) module harness is open or shorted this is fine
          – Throttle Actuator Control (TAC) module circuit poor electrical connection (loose or broken wires) this is fine.

          I guess after breaking this down, a faulty Throttle Position sensor could be the case?

          Read more: http://engine-codes.com/u0107_buick.html#ixzz2QvHePS00

          Read more: http://engine-codes.com/p0068_buick.html#ixzz2QvHNk2a8

          #516284
          Vlad2Vlad2
          Participant

            after further digging, I think its the throttle body as this has the TPS built on it and interacts with the TAC (which comprises of the Throttle Body, the TAC itself and the Accelerator Position Sensor).

            The question is, do I buy a new one on amazon for 180, or go used on Ebay for 70…

            #516821
            Vlad2Vlad2
            Participant

              Easy way to decide if you should get a new MAF sensor first.. drop it off the concrete floor and snap off part of the electrical plug..

              amazon and 2 days later, I’ll know if it was the maf.. lol….

              #516938
              JimJim
              Participant

                these codes all point to the throttle body. as long as MAP, MAF, and the air intake system are good it is a faulty throttle body. how many miles are on this car? the year is under the powertrain warranty for the 10years, and as long as you are under 1k miles this is free at your GM dealer. These throttle bodies can be pricey so i would do that. hope this helps.

                #517072
                Vlad2Vlad2
                Participant

                  Derby, I have 97,000 on it, almost 98,000. I got it as a certified used car. I’ll call the dealer tomorrow if that is the case.. I’ll have to drive it in heavy traffic to get it to code again, but that shouldn’t a problem.

                  thanks, for reference, I found the throttle body on amazon for 180.00 for the AC Delco part, everywhere else was much more. (I try to post all my findings while work on these things).

                  #517119
                  college mancollege man
                  Moderator

                    keep us posted. 😉

                    #518091
                    Vlad2Vlad2
                    Participant

                      It wasn’t the MAF sensor, we’ll see what a new throttle body does on tuesday…

                      #518809
                      Vlad2Vlad2
                      Participant

                        derbycrazy, good call, it was the throttle body / TPS. I got the new one yesterday and tossed it in and it is running great. It hasn’t run this well in a long time. For some reason it is quieter at idle and seems to have more power.

                        #518832
                        college mancollege man
                        Moderator

                          Glad to hear that it worked out.Thanks for the update.

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