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At a wit's end: 327i conversion

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    #1

    At a wit's end: 327i conversion

    Hello all. I wanted to pick your brain as to why I may be having issues with a recent "build" I did. The car is a 1987 325. It has a the 2.7L eta engine to begin with and I went ahead and did the infamous 327i conversion: 325i cylinder head, intake manifold, etc. and all supporting modifications. To the best of my knowledge I didn't skip over anything and did it all correctly.

    Now the problem: it turns over and idles just fine. Hurray! However, when I give it gas, it revs up to around 1,500-2,000 rpm and then stutters (often just stalls and dies). I've been reading for a couple weeks about possible issues and I've tried to rule out everything.

    These are the bits I believe not to be a problem because I tested with spare parts, or tested with a multimeter and found to be within specifications, or cleaned and adjusted to specification:
    - spark plug wires and spark plugs
    - AFM, throttle body, and ICV
    - injectors
    - ECU
    - crank sensor
    - oxygen sensor
    - timing adjustment (collectively idled for more than 25 minutes, so I went ahead and did the 2nd set of adjustments, too)

    This list may be missing some other parts I tested, but no matter -- I'll take any suggestions and if I haven't tested it, I will. I'm just so close to getting it spot on that it's driving me crazy!

    Thank you in advance.
    Tags: None
    #2
    you used the 325i FPR and injectors right? Swapped over FULL 325i harness and all electronics correct?

    Comment

      #3
      what 2.5 head are you using? early and late require different plugs and DO make a huge difference to running of the car. early require the shorter plugs and late the longer ones.

      have you checked for air leaks? the oring under the oil drain tube under the manifold? the manifold gaskets? are the tappets set correctly? not too tight?

      have you checked for fault codes? what dme are running motronic 1.3?

      have you checked the gap to the crank sensor in relation to the teeth? is the reference lug damaged? or are the speed sensor and refernce sensor back to front?

      i had this very issue on a car. turned out the flyhweel had been replaced and the reference lug wasnt right. ment under part throttle map when the lug came around it righted to restart its ignition sequence in the wrong timing.

      Comment

        #4
        Originally posted by e30trooper View Post
        you used the 325i FPR and injectors right? Swapped over FULL 325i harness and all electronics correct?
        Yes, sir. Using a 1989 325i fuel rail and FPR. Tried with 13#, 14#, and 19# injectors, too.

        Complete swap to a 1989 325i Motronic 1.3 harness and all associated electronics.

        Originally posted by e30leigh View Post
        what 2.5 head are you using? early and late require different plugs and DO make a huge difference to running of the car. early require the shorter plugs and late the longer ones.
        1989 325i head, casting is 885. I've tried Bosch Platinum +4 (funky unadjustable plugs) as well as cheapo AutoZone brand plugs. Thoughts?

        Originally posted by e30leigh View Post
        have you checked for air leaks? the oring under the oil drain tube under the manifold? the manifold gaskets? are the tappets set correctly? not too tight?
        Gaskets are solid. Spent a bit of time listening and didn't notice any leaks. I will double check what you mentioned.

        Originally posted by e30leigh View Post
        have you checked for fault codes? what dme are running motronic 1.3?
        Yes, Motronic 1.3 with a 173 DME. I've tested with two 173 DME's, though I can't rule out both being faulty. No check engine light.

        Originally posted by e30leigh View Post
        have you checked the gap to the crank sensor in relation to the teeth? is the reference lug damaged? or are the speed sensor and refernce sensor back to front?

        i had this very issue on a car. turned out the flyhweel had been replaced and the reference lug wasnt right. ment under part throttle map when the lug came around it righted to restart its ignition sequence in the wrong timing.
        Crank pulley is lined up and double-checked. I don't understand what you mean about the sensors and reference lug -- if you could elaborate I will investigate.

        Comment

          #5
          I think e30leigh is talking about the sensors in the bellhousing. On the eta they use a reference pin on the flywheel to determine crank position because it has the smooth crank dampener. The 1.3 system does not.

          I just swapped from a motronic 1.0 to 1.3 and the 1.3 system uses a different CPS and CID sensor instead of the two in the gearbox. One consists of the toothed dampener and the other goes off cylinder 6 spark plug wire.

          To complete the 1.0 to 1.3 swap you need to install the toothed 60-2 crank dampener and associated bracket/cps. You also connect the 325i wiring harness which has the Cylinder Identification (CID) sensor. These two replace the bellhousing sensors from the 1.0 system.

          Did you swap those?
          318iS Track Rat :nice: www.drive4corners.com
          '86 325iX 3.1 Stroker Turbo '86 S38B36 325

          No one makes this car anymore. The government won't allow them, normal people won't buy them. So it's up to us: the freaks, the weirdos, the informed. To buy them, to appreciate them, and most importantly, to drive them.

          Comment

            #6
            Sounds like AFM to me! When I did the conversion it started and idled but I went to drive and couldn't go past 1,5k; I forgot to plug it in, hah. you may need to adjust the afm (and make sure you're running an afm from the i)

            Comment

              #7
              Originally posted by downforce22 View Post
              To complete the 1.0 to 1.3 swap you need to install the toothed 60-2 crank dampener and associated bracket/cps. You also connect the 325i wiring harness which has the Cylinder Identification (CID) sensor. These two replace the bellhousing sensors from the 1.0 system.

              Did you swap those?
              Awesome explanation -- much appreciated. Yes, those are swapped and set up correctly :up:

              Originally posted by squidmaster View Post
              Sounds like AFM to me! When I did the conversion it started and idled but I went to drive and couldn't go past 1,5k; I forgot to plug it in, hah. you may need to adjust the afm (and make sure you're running an afm from the i)
              Yes, it's a good AFM from an 'i' but I will quadruple check, just so I don't look like a moron in a month finding out it really is and issue with the AFM.

              Comment

                #8
                Have you checked the rail fuel pressure?
                The car makes it possible, but the driver makes it happen.
                Jim Levie, Huntsville, AL

                Comment

                  #9
                  open the little black box on the afm (use a blade to slice through the adhesive)
                  there's a phillips head screw that's recessed in the center of the wound spring. you can loosen that a little and adjust the head that goes onto the carbon. I believe toward the front of the car is rich and the rear is lean but I could have it backwards.

                  just remember to unplug the afm before adjusting--there's a bit of open metal in there.

                  Comment

                    #10
                    Originally posted by jlevie View Post
                    Have you checked the rail fuel pressure?
                    AH!!!! now what fuel system are you running? the single in tank high pressure pump. or the double low pressure lift pump with external high pressure pump?

                    i have also experianced where the high pressure died on the double system leaving the low pressure lift pump which can supply enough fuel for idle and very low revs. but left the car leaning out and stalling with anything more then that.

                    fuel pressure and flow gauges will show that. minimum requirements are 2l per minute and 40psi at idle. anything above that is great. below that are you have your problem. make sure you have both flow and pressure gauges. one without the other is useless as a bad pump can still supply pressure but not enough flow and visa versa.
                    Last edited by e30leigh; 10-21-2012, 09:09 PM.

                    Comment

                      #11
                      and bosch w8LDC i believe is the part number you need for your car. there should be 2.5/2.7 stamped above exhaust port 2 to double check its late model over the 885 casting on the intake side.

                      Comment

                        #12
                        didn't only m42's get the double pump?

                        he has a single pump.

                        Comment

                          #13
                          nope. my fl m40 has double, as does my 320i fl m20 yet my friends fl 325i has single.

                          Comment

                            #14
                            easy to check without getting under the car. if its double then the filter is under the brake master. if its not there its a single pump

                            Comment

                              #15
                              okay so only 325 and m3 got single pump then?

                              Comment

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