Problem with High idle and Air Conditioning

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  • bimmerphile
    No R3VLimiter
    • Oct 2003
    • 3495
    #1

    Problem with High idle and Air Conditioning

    89 325i, M20B25 Engine with 173 ECU + JC chip.

    Normal driving - idle ~750rpm
    A/C on - idle ~1000-1500rpm

    When I make a shift, or go into neutral, the revs hang at around 1500 before they drop out all the way to idle as well.

    thus far I have:

    Loosened micro-adjustment screw. This fixed the problem temporarily, however as soon as I turned on the A/C the revs jumped back up to 1500 before settling out at 1000 again.
    cleaned the icv each time i fart around with this thing, it seems to fix it for about 5 minutes. also, I swapped it with an ICV from another 325i, to no avail.
    ran BG-44k through the engine (carbon deposit/fuel system cleaner)
    I couldn't find any vacuum leaks.
    I swapped the ECU to see if that makes a difference, and it didn't

    Perhaps the temp sensor is to blame?

    thoughts/ideas?

    Again, this only happens with the A/C on.
    My mountains are better than yours.
    Tags: None
    • bimmerphile
      No R3VLimiter
      • Oct 2003
      • 3495
      #2
      how bout a bump. no longer happens with jsut the A/C, and with the A/C on new idle is almost 2k rpms.
      My mountains are better than yours.

        Comment

        • EtaSport
          R3VLimited
          • Oct 2003
          • 2853
          #3
          Our 528e did this after we got it. It is auto, lots of miles. When in gear it was perfectly fine, but put it in park or neutral and the rpms skyrocketed. We got by just shutting it off in drive. Then the AC started acting up. Running R134 now, and the idle surged in gear and out.

          Check for any vacuum leaks, make sure your TPS is set right, and make sure the throttle butterfly is closing all the way. You can check the connections of all the important stuff, but I think what solved our problem was the ICM. The only thing is I dont think there is an ICM on the 325i, and if there is im not sure where it is. I looked for it on ETK and didnt find it. Vacuum leaks are big, variances in fuel pressure are big, and that ICV is just plain weird. The m20 is such a hard motor to diagnose. Hope maybe something helps out.
          Old and improved:

            Comment

            • Jand3rson
              Banned
              • Oct 2003
              • 37587
              #4
              Kris, I didn't know you got another E30.

                Comment

                • Court M3
                  R3V OG
                  • Jan 2004
                  • 6713
                  #5
                  Yeah show pics of the new E30!
                  Continuous For Sale Thread
                  323i s50

                    Comment

                    • bimmerphile
                      No R3VLimiter
                      • Oct 2003
                      • 3495
                      #6
                      Thanks for the replies. I may just take this one into the mechanic and have them deal with it.



                      Pics will come. School is sucking a lot of time away right now, and that's the priority.
                      My mountains are better than yours.

                        Comment

                        • e30evolution
                          West Werks
                          • Oct 2003
                          • 1888
                          #7
                          when you turn on the a/c the computer make it idle faster to compensate for the extra load.

                          http://www.westwerksauto.com

                            Comment

                            • bimmerphile
                              No R3VLimiter
                              • Oct 2003
                              • 3495
                              #8
                              Originally posted by e30evolution
                              when you turn on the a/c the computer make it idle faster to compensate for the extra load.
                              I understand that. So I switched ECU's, and it was unchanged.

                              where does the ECU get that information?
                              My mountains are better than yours.

                                Comment

                                • e30evolution
                                  West Werks
                                  • Oct 2003
                                  • 1888
                                  #9
                                  i dont know if there is an actual problem..... just how things are. there is a temperature sensing bulb on the evaporator that tells the computer when it is getting too cold, and one of the condensor to tell when it is getting to hot. basically letting the clutch cycle on and off when necessary. only 1500? there is no problem, just how it is

                                  http://www.westwerksauto.com

                                    Comment

                                    • bimmerphile
                                      No R3VLimiter
                                      • Oct 2003
                                      • 3495
                                      #10
                                      Originally posted by e30evolution
                                      i dont know if there is an actual problem..... just how things are. there is a temperature sensing bulb on the evaporator that tells the computer when it is getting too cold, and one of the condensor to tell when it is getting to hot. basically letting the clutch cycle on and off when necessary. only 1500? there is no problem, just how it is
                                      1500-2000. peaks at 2200-2400.

                                      Never has happened before, but winter's coming, so I suppose it's not that big of a deal for long.
                                      My mountains are better than yours.

                                        Comment

                                        • Mystikal
                                          Moderator
                                          Wheel Fitment Expert
                                          • Nov 2003
                                          • 9602
                                          #11
                                          Originally posted by e30evolution
                                          only 1500? there is no problem, just how it is
                                          If your car idles at 1500 with the A/C on you have problems.

                                            Comment

                                            • bimmerphile
                                              No R3VLimiter
                                              • Oct 2003
                                              • 3495
                                              #12
                                              Originally posted by Mystikal
                                              Originally posted by e30evolution
                                              only 1500? there is no problem, just how it is
                                              If your car idles at 1500 with the A/C on you have problems.

                                              Now it's at around 2000.

                                              ^bump for the tech advice.
                                              My mountains are better than yours.

                                                Comment

                                                • bimmerphile
                                                  No R3VLimiter
                                                  • Oct 2003
                                                  • 3495
                                                  #13
                                                  new ideas?
                                                  My mountains are better than yours.

                                                    Comment

                                                    • hotghias
                                                      Advanced Member
                                                      • Jan 2004
                                                      • 148
                                                      #14
                                                      sorry i can't help... but at least your engine keeps running when your ac is on.... unless my car is pretty well warmed up it stalls whenever i put the clutch in to shift

                                                        Comment

                                                        • bddog
                                                          Grease Monkey
                                                          • Feb 2004
                                                          • 351
                                                          #15
                                                          The Idle Control Module controls the idle- not the ECU. It is located next to the ECU under the dash on top of the glove box. Black for early models, Green for later ones. If you replace it Green is the color you want. They are supposed to last better---- Steve

                                                            Comment

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