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    AC Idle bump

    I saw a thread on this but nobody seemed to have a definitive answer in it. I have hooked the violet wire from the AC Switch (switched 12v) to the Violet/grey wire on the DME harness. Yet Idle does not change when the button is pressed. I have an early model car 3/1985 and the motor set up is a M52 , obd2. Anyone else with this setup have their idle bump working?


    #2
    Bump. I'm interested also before I finalize my wiring.

    '91 318is - OBD-II S52 swapped - E30 M3 5-lug - 5x120 BBS RC090 (E39 Style 5) - TCK D/A coilovers 550/700 [SOLD]
    '87 535i - Vacuum brake conversion [SOLD]
    '93 525iT - 5-speed swap - 320k and counting
    '09 328xi - 6-speed

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      #3
      Did you try forcing 12v to the ecu wire btw? Forgot to ask

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        #4
        Originally posted by 328ijunkie View Post
        Did you try forcing 12v to the ecu wire btw? Forgot to ask
        the wire from the switch is confirmed 12v, the compressor sounds weird and seems to be putting too much load on the motor though.

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          #5
          not possible to get to work. E36 climate computer sends coded signal to DME to turn on the compressor and bump the idle. Not possible to get it working on E30.
          Last edited by DesertBMW; 07-02-2014, 03:22 PM.

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            #6
            Originally posted by DesertBMW View Post
            E36 compressor requires PAG46 oil, the PAG oil is glycol based and will dilute with 134a and when the system is emptied some of the oil will be gone too. Probably low on oil.

            if you used ester oil the compressor will not last more than 2 years



            That is because the 413 ecu needs a signal from A/C pressure switch that is located on the filter dryer, at pin 65. The way that you have is, the ECU knows that you turn on the A/C system but it will not activate it's "IDLE UP" unless it knows that system is full. The ecu controls the compressor on E36.
            Could this be the case for me? I'm running OBD2 so non 413 ecu, so you're saying I need to run a wire from the low pressure switch to the violet / gray and it should trigger the idle bump?

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              #7
              ^ Doesnt work that way.
              Im still investigating. Basically that bk/gray wire runs from climate control unit. Through Pressure switches back to ECU to tell the ECU its okay to fire the compressor.

              Check Us out on Facebook
              Needing a harness adapter or wiring help? Check it out: also have 24v motor mounts, E30 M3 covers and E36 ECU mounts!
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                #8
                Note: 93 325 M50B25TU to an 88 E30 325is

                When the idle bump signal is passed back to the ECU, doesn't it go through X20 pin 5 (bk/gy) on the E36? On the E30, the low pressure signal comes from a black/red wire on the low pressure switch, around the front of the engine and down the left side harness into the C204 connector, then over to the C136 and on to the ECU at pin 40.

                I'm thinking that cutting the Bk/Rd wire near the firewall and then running it through an unused C101 pin, then into the X20 pin 5 should do it. Does that sound plausable?

                Tim
                Tim
                Indianapolis, IN, USA
                88 325is (M50)
                92 525iT (5 speed)
                98 328is
                2011 535is
                69 Fiat Spider
                68 Fiat Spider (122nd chassis built for the US)

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                  #9
                  i posted this in another thread, but i think it'll be better here..

                  my thinking is that on the e30, the a/c compressor 'on' signal comes from the c211 connector, which goes straight to the DME:




                  whereas on the e36, the DME receives an input from the pressure switch through x20pin5, which then goes to the ecu.




                  so i assume it would be correct to run the lead from c211 to an unused pin on the body-side c101, which will then correspond with the e36's x20pin5. if you're repinning the x20 wires into the c101 connector, it's just a matter of lining up pin-to-pin.

                  Originally posted by 88E30M50 View Post
                  Note: 93 325 M50B25TU to an 88 E30 325is

                  ...

                  Tim
                  hi uncle tim! eric here.
                  Last edited by evandael; 06-19-2012, 01:33 PM.

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                    #10
                    hate to bump up an old thread - but does anyone have a difinitive answer yet as to the work around of the plug and idle?
                    1988 325 "super ETA" - Hilde - M52B28 swapped...
                    1969 2002 - Griselda - 20VT AWP swap and full resto in progress...

                    sigpic

                    project blog - http://www.cynicalmotorsport.blogspot.com/

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                      #11
                      agreed. 1+ - definitely solution here?
                      (oo=[][]=oo)
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                        #12
                        Originally posted by Cynical 1 View Post
                        hate to bump up an old thread - but does anyone have a difinitive answer yet as to the work around of the plug and idle?
                        Originally posted by r4esh View Post
                        agreed. 1+ - definitely solution here?

                        I'm still looking as well, though I made this thread. It turned cold so there really wasn't a reason for using the AC. But now that it's about that time for the temps to start rising. I want to do this right.

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                          #13
                          indeed. i actually used mine briefly last week when we had the 70+ degree day...
                          1988 325 "super ETA" - Hilde - M52B28 swapped...
                          1969 2002 - Griselda - 20VT AWP swap and full resto in progress...

                          sigpic

                          project blog - http://www.cynicalmotorsport.blogspot.com/

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                            #14
                            Originally posted by Cynical 1 View Post
                            indeed. i actually used mine briefly last week when we had the 70+ degree day...
                            Without the idle bump sorted?

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                              #15
                              Originally posted by 325e10 View Post
                              Without the idle bump sorted?

                              correct. driving is fine, it's only when you come to a stop that it hunts for a few seconds and then evens out...

                              still like to know how to eliminate that though...
                              1988 325 "super ETA" - Hilde - M52B28 swapped...
                              1969 2002 - Griselda - 20VT AWP swap and full resto in progress...

                              sigpic

                              project blog - http://www.cynicalmotorsport.blogspot.com/

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