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    #1

    m30 down on power

    So I've suspectd for a while, and it was confirmed this weekend by His Holiness Pope Crivellone, that my m30 is down on power.

    When I bought the motor in 2010 out of a running, driving 535i it had been well-maintained by an enthusiast and was in great shape. In fact when I pulled the intake manifold to paint it I honestly thought the head had been rebuilt (I confirmed with the PO, it hadn't)

    But lately I'm noticing that it's just not pulling like it should. It idles fine and I've recently replaced the TPS after finding it was not sending the proper WOT signal. But still I don't seem to be making the power I should. So I figure I'll tear in to it and do the cap, rotor, plugs and water pump... should I do the wires too? I think the motor has about 150k on it at this point and I'm sure they're original.

    Anything else I should check? Oh and I should probably mention it has the Miller WAR/MAF setup on a stock Miller tune for 91 octane and stock rev limiter.
    Tags: None
    #2
    Add a turbo?

    Maybe you are just used to the power? If i was in your shoes i would hook a wide band 02 sensor up and check AFRs. A trip to the dyno will also confirm power/AFR levels accurately.
    Lorin


    Originally posted by slammin.e28
    The M30 is God's engine.

    Comment

      #3
      Last time I drove mine I felt like it was down on power. This was confirmed when I was giving a friend a ride and jumped on it. It pulled decent, but when I hit about 5k it really got going. Even my friend jokingly said "vtec kicked in" haha.

      I know the plug wire closest to the firewall has no retention to the plug, so I'm thinking that is the culprit.
      1991 335is in progress

      Comment

        #4
        Have you checked your compression and/or fuel pressure? How's your clutch holding up? Perhaps your coil's getting tired?

        Just some ideas, would be tough to pinpoint anything without seeing it in person.

        I miss the old BMW

        Comment

          #5
          This is a little embarrassing, But the backstop for my gas pedal slowly backed out over the course of 3-4 months, and I wasn't getting full WOT with the pedal. I was so relieved when I discovered the problem.

          Easy to check, open hood, stand up with the door open, reach your leg inside depress the pedal and make sure you're getting WOT.
          Originally posted by Matt-B
          hey does anyone know anyone who gets upset and makes electronics?

          Comment

            #6
            Haha, reminds me of the time my Mom told me her e34 had a high idle. Didn't find any vac leaks, just the floor mat jammed into the accelerator...

            I miss the old BMW

            Comment

              #7
              I'l check the compression and fuel pressure when I tear in to it for a tune-up. The clutch was nearly new OEM e28 M5 when i put it in, and it still grabs fine. The coil was sued though so I suppose that could be suspect. Any way to test those?

              Comment

                #8

                1. With the ignition (OFF) remove the coil high tension lead.
                2. Remove the leads from the coil and measure the resistance at terminals 1 and 15.
                  1. Resistance should be 0.5 ohms (+10%). Replace as necessary.
                3. Measure the resistance at terminals 15 and 4 (center tower).
                Resistance should be 6k Ohms (+10%). Replace as necessary.


                1. Check coil insulation plate for signs of hair line cracks, or burning. Replace as necessary.
                2. Check tightness of plug (S), if pressed out, replace the ignition coil.

                I miss the old BMW

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