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    325i running rough on startup

    I've been having a problem on start up with my 325ix.

    Last week I made short spirited drive with my brother. I let it idle when opening the garage and when coming back to the car, coolant was overflowing from the overflow tank. (Temp needle was just about the 3/4 mark).
    I've had coolant spilling before after shutting it off and letting it sit. I think I might have filled it a bit too much.

    When I now start the engine, it's running pretty rough. When I give it some slight gas (1500-2000rpm) a few times, it idles perfect like it did before. If I don't give it some gas at start up and just start driving, the car bogs down a little, it's like it's running on 5 cilinders. After a maybe 50-125meters it runs fine.

    Could this be the symptoms of a blown headgasket? There isn't any white smoke puffing out of the exhaust + oil and coolant still look good.
    I don't have a compression tester but I do want to get one soon.

    Other thing that I think it could be it stuck injectors? Leaving the pistons wet at start up, causing it to be too rich and making it running rough? Giving it some gas burns the excessive fuel away?

    What do you guys think? Any other suggestions on what it could be?
    1990 325iX Touring - November 2018 R3V Car Of The Month

    1980 Volkswagen Golf mk1 1.1
    1974 BMW 2002 Touring

    Instagram

    #2
    I would pull the spark plugs and see if they tell you anything. Then a compression test.
    2004 525i Manual - 1985 325E Coupe Manual

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      #3
      Originally posted by tomstin View Post
      I would pull the spark plugs and see if they tell you anything. Then a compression test.
      As you mentioned, I pulled the sprakplugs today. They all look pretty much the same.

      1


      2


      3


      4


      5


      6, this one might have some more deposits than the other ones but nothing to extrme
      1990 325iX Touring - November 2018 R3V Car Of The Month

      1980 Volkswagen Golf mk1 1.1
      1974 BMW 2002 Touring

      Instagram

      Comment


        #4
        Compression test it.
        john@m20guru.com
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        Transaction feedback: Here, here and here. Thanks :D

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          #5
          Change the coolant temp sensor. This sensor helps the ECU set the correct fuel mixture for your engine when it is cold until the O2 sensor warms up to operating temps.
          Last edited by RobDog; 07-25-2018, 07:31 PM.

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            #6
            Originally posted by RobDog View Post
            Change the coolant temp sensor. This sensor helps the ECU set the correct fuel mixture for your engine when it is cold until the O2 sensor warms up to operating temps.
            This one has been replaced only 150-200kms ago. I expect these don't go bad that early.?
            Last edited by D.Martijn; 07-31-2018, 02:57 AM.
            1990 325iX Touring - November 2018 R3V Car Of The Month

            1980 Volkswagen Golf mk1 1.1
            1974 BMW 2002 Touring

            Instagram

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              #7
              Finally got the time to test my compression. (I borrowed a tester from a friend but I couldn't tighten it enough)

              I measured the blue temp sensor that's fitted now and an old one I had laying around. Both were around 20°C and got 2.3kohm. I found a datasheet on the Bosch website which stated 2.5komh at 20°C I don't think that's going to be to problem.

              Datasheet here:


              After getting my new tester, these are the results I got (These measurements are with the engine cold)

              1. 12.25bar - 175psi
              2. 12.25/12.5bar - 175-180psi
              3. 12.5bar - 180psi
              4. 12.75bar - 182.5psi
              5. 13bar - 185psi
              6. 12.5bar - 180psi

              Looks good to me?

              When removing the sparkplugs I did notice that the 5 & 6th cylinder are running a bit more rich? This was after starting the engine and letting it run a minute or 5. Could it be that the injectors are leaking on the 5th and 6th cylinder? Causing it to run lumpy on startup, clearing the excessive petrol by revving it slightly?

              Left to right (4 - 5 - 6)
              1990 325iX Touring - November 2018 R3V Car Of The Month

              1980 Volkswagen Golf mk1 1.1
              1974 BMW 2002 Touring

              Instagram

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                #8
                Looks like you might be leaking oil into #5&6, maybe a little in #4. Oil passing through the valve stem seals will not only make the plugs darker, it will cause higher compression readings as the oil seals the rings....
                john@m20guru.com
                Links:
                Transaction feedback: Here, here and here. Thanks :D

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                  #9
                  Originally posted by ForcedFirebird View Post
                  Looks like you might be leaking oil into #5&6, maybe a little in #4. Oil passing through the valve stem seals will not only make the plugs darker, it will cause higher compression readings as the oil seals the rings....
                  Seems to be running pretty rough for leaking only some oil through the seals though? When driving the car the exhaust smoke isn't blue or I don't notice the engine oil dropping..
                  1990 325iX Touring - November 2018 R3V Car Of The Month

                  1980 Volkswagen Golf mk1 1.1
                  1974 BMW 2002 Touring

                  Instagram

                  Comment


                    #10
                    Wasn't exactly diagnosing the rough running issue - that's tough enough to do in real life lol. I was more explaining the color on the plugs.

                    Do you have the round c109 connector under the intake manifold that powers your injectors/CTS's? That's a common problem spot for rough running.
                    john@m20guru.com
                    Links:
                    Transaction feedback: Here, here and here. Thanks :D

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                      #11
                      Originally posted by ForcedFirebird View Post
                      Wasn't exactly diagnosing the rough running issue - that's tough enough to do in real life lol. I was more explaining the color on the plugs.

                      Do you have the round c109 connector under the intake manifold that powers your injectors/CTS's? That's a common problem spot for rough running.
                      Ah, sorry I misunderstood.

                      I'm not sure, I haven't checked that connector. what I did notice is when I shut it off after letting it idling a a bit until the problem is gone and start it up after a few minutes I don't seem to have the problem.

                      So I'm currently thinking it might be the fuel injectors leaking..?
                      1990 325iX Touring - November 2018 R3V Car Of The Month

                      1980 Volkswagen Golf mk1 1.1
                      1974 BMW 2002 Touring

                      Instagram

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