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Can somebody please help me diagnose this?

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    #1

    Can somebody please help me diagnose this?

    Update below. I've determined this surfaces when it's raining out.

    Hello everyone. I drive an 89 325i and it has intermittently started acting funny.
    Here are the symptoms I've noticed: (my heavily inexperienced guess is fuel pump)
    1) Sometimes when I accelerate the power feels inconsistent, almost like it's getting fuel then not getting fuel, repeatedly, throughout the rev. At first I thought it was my clutch slipping, but I'm 95% that's still good. I can downshift from 3rd to 2nd and it grips no problem. This appears to be most reproducible after the car's been sitting for a while and I try to accelerate quickly as soon as I turn it on. It goes away after a minute or two. The first time I noticed it was after a 200mile highway trip. I got into town and when i slowed to 2nd gear trying to accelerate wasn't really happening. The tach stays where you'd expect it for the speed, again why I don't think it's the clutch.
    2) The car has always taken a few cranks to turn on, maybe a second at most (since i bought the car 2000 miles ago, anyway). Now seemingly randomly it will sometimes take 5-10 seconds of cranking before it'll finally fire up. I think it's related to how cold it gets out at night, but then again some cold mornings it'll fire right up.

    So like I said my hunch is the fuel pump, but this is my first project car and I definitely don't have any mechanic/automotive experience.

    Thanks for any help!!

    Brian
    Last edited by peller; 01-14-2007, 08:23 PM.
    Tags: None
    #2
    There's another thread where this is being discussed. I have the same problem, and I think (and so do others) that it's either of three things: the crankshaft position sensor, the distributor/rotor and ignition wires, or the fuel pump.

    What I'm going to do is get a new CP sensor and distributor and rotor. Those parts aren't that expensive, and may just solve the problem. If it doesn't, I'll probably get a new fuel pump and replace the ignition wires later. Does your fuel pump whine or make any noise, like the sound of an angry beehive? If it does, then your fuel pump is probably taking a shit.

    Good luck. Hope that helps.
    1988 325ic Automatic

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      #3
      To add a little more, it could be a vacuum leak, but I doubt it. I replaced a couple of hoses in the intake system and the fuel pressure regulator, both of which weren't expensive. It might be worth it to replace the FP regulator (because it can cause symptoms of a failing fuel pump), but I'd also look at your hoses to see if there are any noticable cracks in the rubber. You can spray carb cleaner on your hoses while the car is running; if you notice a pitch change, you have a vacuum leak.
      1988 325ic Automatic

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        #4
        I had a similar problem and I tried the obvious (water in the fuel, leaking vaccuum hoses, checking for cracks in the rubber assembly tube that connects to the throttle body) and the only thing that remedied the issue was replacing the computer. A new computer was too cost prohibitive for me at the time so I ended up searching every junkyard around the US. My mechanic advised me to keep the VIN handy during my search because if I could find one from a car that was close to mine on the assembly line there was a good chance that it would work for me. After two attempts, I was able to get one that worked. Ever since I got my car going again, I still have my doubts as to whether replacing the computer fixed the problem or if I just had a loose or broken wire going to the ECM.

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          #5
          Originally posted by Jscotty View Post
          I had a similar problem and I tried the obvious (water in the fuel, leaking vaccuum hoses, checking for cracks in the rubber assembly tube that connects to the throttle body) and the only thing that remedied the issue was replacing the computer. A new computer was too cost prohibitive for me at the time so I ended up searching every junkyard around the US. My mechanic advised me to keep the VIN handy during my search because if I could find one from a car that was close to mine on the assembly line there was a good chance that it would work for me. After two attempts, I was able to get one that worked. Ever since I got my car going again, I still have my doubts as to whether replacing the computer fixed the problem or if I just had a loose or broken wire going to the ECM.
          That's really weird. I hope it doesn't come to that.
          1988 325ic Automatic

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            #6
            Thanks for the tips guys. I haven't had a chance to check anything out just yet but I'll report back when I do.

            325iCabrio: I found that thread you were referring to, some good info in there, thanks.

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              #7
              UPDATE: Looks like the problem surfaces when it rains and the engine bay gets wet from below. After about 100 miles of driving in the rain the car started to chug with inconsistent power. I also noticed the gas milage gets shot to shit. I would describe the sound coming from the engine as a helicopter, maybe like the pistons are firing at untimed intervals? The car idled like fuck after that too, around 600rpms when it's normally about 900.

              I should mention that my exhaust is wasted at the muffler right now, but I've got a new IE catback waiting to be installed whenever it dries up and i can get under the car. Is it possible that this could be messing with the O2 sensor? I kinda doubt it but what do i know.
              I did notice one small crack in the 90 degree rubber piece where that bosch intake thingy is after the filter.

              I'll have to check in the morning after it dries up to see if the problem decided to linger.
              Thanks guys.

              Comment

                #8
                the crack in the intake boot is part of you problem. I would look into a new a cap, rotor, wires an plugs. Also the AFM it self.
                Originally posted by Fusion
                If a car is the epitome of freedom, than an electric car is house arrest with your wife titty fucking your next door neighbor.
                The American Republic will endure until the day Congress discovers that it can bribe the public with the public's money. -Alexis de Tocqueville


                The Desire to Save Humanity is Always a False Front for the Urge to Rule it- H. L. Mencken

                Necessity is the plea for every infringement of human freedom. It is the argument of tyrants.
                William Pitt-

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                  #9
                  I had a similar problem and the circuit board on the inside of the AFM had a small crack in it that was causing the AFM to read that the throttle was closed when it was in fact wide open. This was causing my lean condition.


                  Nick

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                    #10
                    Could also be cracked plug wires, if they are cracked and it is wet you will send your plugs to ground instead of sparking. If you have the car on use a misting spray bottle and spray the wires. If you do it with low light and you see blue electricity then it is your plug wires. This condition only happens when it rains or if you live in an area with high humidity.

                    Comment

                      #11
                      Oh wow. I missed this thread. I am having the same exacly problems, except you described them better.

                      Now that i think of it, it usually happens a lot more when the weather is bad (raining/snowing).


                      http://www.r3vlimited.com/board/showthread.php?t=80827


                      I'll post an update when i figure out my problem

                      Comment

                        #12
                        wow, its like my car read this thread and decided to do this to me today. I know that it better not be wires/plugs/rotor/distributor because I did them all less than 6k ago. It was bogging, bucking, and barely running, so I parked it and took another car to work today. My dad got home, unplugged the MAF, blew on it, plugged it back in & started the car. He said the CEL came on at first, but them the car got all better and acted completely fine...

                        Looks like I'll be making a fuel filter purchase soon

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                          #13
                          So last night it was bitter cold and the car had been sitting outside in 5 degree weather for about 5 hours since I'd last used it. I turned the ignition, it started up, and literally ran like fuck. It reminded me of an old beat up truck, sounding like it was trying oh so hard to run but just couldn't keep going. The car then proceeded to stall on me. When I tried to start it up again it wouldn't start until i pumped the gas a lot. From what I've read this indicates that the engine isn't getting nearly enough air, correct? How would I go about testing the air flow meter?

                          Once I got it started again I figured I'd rev the engine and kept it around 3k for maybe 10 seconds, just to warm it up. The car then proceeded to idle at 2k rpms (no joke, it just chilled there). I could drive it fine at this point, power was strong/consistent - everything felt normal except the high idle. After about 2 miles of stop/go city driving it proceeded to idle like normal and continued to run perfectly fine.

                          After I get out of class I'm going to search around for more vacuum leaks and check the ignition wires with that misting trick. Is it bad to patch the crack in the rubber piece after the air flow meter with something like PC7? I only see the one crack and I'm feeling rather frugal right now :D.

                          Brian

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                            #14
                            I've also had the problem where the car would start but it sounded so bad (like an old ass truck) and I had to keep pumping gas for it to stay on. It then proceeded to stop after driving a while. That happened once or twice a few months ago and nothing since. weird!

                            Comment

                              #15
                              It sound's like a few of us are having the same problem. Im almost dead set on it being fuel pump/filter/ or injectors. Im still not positive its not the AFM.

                              Nick, what did you end up doing to fix the problem with your AFM? I might buy a new fuel filter today and see if that helps...

                              -Paul

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