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E30 starting problems

Discussion in 'E30 (1984-1993)' started by tgor, Aug 12, 2008.

    tgor guest

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    I am having trouble getting my E30 started. I recently purchased the car and had it towed home. Since then I have drained the bad fuel and replaced the fuel filter. The car will start but immediately dies. I do know that I am getting voltage at the cold start injector and assume that it is working because it does start. I am currently thinking that injectors are not getting the signal to fire and was wanting to get an idea if anyone else has had a similar problem. This engine has the Motronic system. Does anyone know what kind of voltage I should be reading at the individual injectors? and is there a more accessible place to check voltages without removing the manifold?
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    mooseheadm5

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    If the car sat for a long time and the fuel turned to varnish, it could have stuck the injectors. You obviously have spark, which means you have crank pulse. The way I do it is to have someone fog the intake with carb cleaner to keep the car running while I tap on the injectors with a socket extension to free them up. It must be done while running because the computer is pulsing them. If you want to test for injection pulse, you can access the #1 injector plug without pulling the intake.

    tgor guest

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    Thanks. I'll try that before pulling the intake. Sounds like it ought to work.

    So you do think I am getting a pulse to the injectors based on the spark plugs firing? To be honest I am not real familiar with electronic fuel injectors. I friend of mine is going to let me borrow his 'noid light' which would tell me if I am getting a signal.

    hefferonjm guest

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    You could get out the trusted auto stethescope and place it on top of the injector to listen for the injector opening. It should make a clicking sound. If you don't have one Northern Tool sells them for about $15 or in a pinch a long screwdriver will work, just not as well.

    Old gas can kill a fuel pump pretty quick as well. It may be able to pump enough to get gas up to the rail, but if its too weak to provide the pressure or volume needed the engine won't be able to run. A fuel pressure and volume test would be a good idea to give you a heads up on the condition of the pump. Pressure should be 3.0 bar +- 0.05 which is about 44 psi +- 1, volume should be 0.875 ltr/30 seconds. ( as per bentley) I hope this helps.
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    mooseheadm5

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    The noid light will tell you if you are getting injection pulse. The fact that you have spark tells me the ECU is on (good main relay and not blocked by the code module) and that the ECU is getting crank pulse. Let us know what turns up.

    tgor guest

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    Thanks for the heads up I will check the fuel pressure. It was seized when I got it and runs a little noisy right now. I went ahead and pulled the manifold anyway figuring it needed cleaned up along with the injectors.

    Thanks for the info on the ECU I know what they do but was unsure of the rules they follow doing it.

    Anyway cleaning up the manifold, injectors, and throttle body now and picking up a intake manifold gasket on Monday. Hoping to have some good quality under the hood time this week and have her running by the weekend.
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    Jenny Morgan

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    More information

    What year and model? E or I early late... it all matters.

    Have you checked the fusible link in the trunk off the battery? What condition is the connector under the intake manifold? How about the timing sensors?:cool:
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    mooseheadm5

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    Thanks for pointing all that stuff out (love your column, by the way.) It is often hard to tell if someone can take every possibility at once and process it, or if they need to be talked through. I like to break non-start issues down to fuel, spark, and compression. If it has spark and fuel pressure (which this might as it starts and then dies, and he did mention the cold start injector and Motronic, so I assume it is a 325e before 88) then it seems that there may not be injection pulse or if there is the injectors are stuck (or other possibilities- see below.) If no pulse, I would assume that the fusible link is OK because it tries to start and that link usually only takes down the main relay. So, I believe by reading that it has spark (but that is a guess by reading) and therefore has ECU function.

    So, the following are possibilities:
    1) the fuel pump is not providing adequate fuel
    fuel pump is not running after it is done cranking (ECU problem)
    2) ECU is not telling the injectors to turn on (ECU problem if there is spark, sensor problem if not)
    3) the injectors are not getting the signal to open (bad wiring because there is no connector under the intake on an early 325e)
    4) the injectors are not being opened because they are stuck
    5) the timing reference sensor (not the TDC sensor) is bad causing the car to start and die - if so, it would not run on carb cleaner
    6) the air flow meter is unplugged or the wiring is bad

    Testing for injection pulse will cover 2, 3, and 4 (if it runs on carb cleaner). Fuel pressure test will cover 1 (especially if done while running on carb cleaner.) Running it on carb cleaner covers 5 and possibly 6. Good luck. Please let us know how it is going.

    tgor guest

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    I was cleaning the injectors and noticed that they were stuck. After cleaning them and putting the intake all back together I found that this fixed the problem. I had other difficulties to get it running just right like the mass air flow sensor stuck open at some point and the small connectors on the back of valve cover had lost their retaining clips and come apart.

    Anyway I got it running pretty good. However when I hit the throttle (somewhat aggressively) it seems to hesitate near the point of stalling before revving up. Once past the idle point I don't seem to have this problem.

    Right now I got the fuel pressure regulator apart because I ripped the rubber O-ring during assembly.

    Thanks for your help.

    BTW its a 84' 325e 5-speed 2-door
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    Jenny Morgan

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    next...

    Have you pulled any plugs? How old is the fuel filter?

    tgor guest

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    I have not pulled the plugs but I replaced the fuel filter when I drained the bad gas. Also I replaced the intake manifold gaskets. There does not seem to be a miss at idle and seems to run smooth once it starts to accelerate. It seems to hesitate during acceleration but once above about 1500 rpm it's right on target and will increase revs upon my demand. The hesitation I am getting does not vibrate as one would expect with a miss or bad spark but one that seems to be caused by to much or to little air.
    As I type I am wondering if I am getting an erratic signal from the mass air flow meter.
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    Jenny Morgan

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    plugs?

    I ask because I have seen more than one M20 that had worn to death plugs that hesitated on accel then smoothed out... Gotta know where the basics are at.
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    mooseheadm5

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    I love being right :)
    Anyhow, check the plugs first, then the cap and rotor. The hesitation may also be caused by a sticky air flow meter flapper door. If your binds in any way, start by cleaning it out and working the door back and forth by hand. If it is sticky near the idle point, it may not meter properly. Glad you got it fixed. If you don't know when the timing belt was changed, change it now. I only use tensioners from the dealer. I got my latest E30 for $200 because the previous owner didn't want to spend money on the timing belt. Quite a deal, too. Has a glass sunroof and a maplight rear view mirror. Come to think of it, that is the second one I got for $200 because of a snapped timing belt. The first was the donor for the head I ported and all the electronics I needed to convert my 325e to a 327i. See my point, though?

    tgor guest

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    I should be getting the new seal for the fuel pressure regulator tomorrow and will go ahead and check the spark plugs. Its a simple inspection that will only take about 30min. I'll check the mass air flow sensor as well sounds very probable that could be the issue.

    Thanks for the heads up on the timing belt sometimes we need to be reminded to do a little preventive work to prevent disasters. I got lucky twice on a sheared timing belt for two other vehicles and don't wish to try my luck on a third.

    tgor guest

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    Got the new seal installed and loosened up the MAF sensor. This has fixed the hesitation problem. It runs like a top now :D
    I am getting the flashing light in the center of dash called the "Active check control" and was wanting to know if anyone knows of a trick to figure out which code its throwing?:confused:
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    granthr

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    It always flashes upon start up to get you to put your foot on the brake pedal so it can check your brake lights. If it continues to flash look up at the info center at the top of the windshield. An LED should be lit to tell you what need attention. Then just press the check button to get the dash light to stop flashing.

    GR

    tgor guest

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    Cool thanks for the info I wasn't sure if was connected to the engine as in emissions or temp sensors. All I'll need to do is add washer fluid then. I like those types of 'repairs':)
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    granthr

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    The check control panel can go haywire as it gets older, giving false warnings. Sometimes it is just a matter of cleaning the contacts in your rear taillights and making sure you have quality euro bulbs back there. So don't always trust it, be sure to check vital fluids manually!

    GR

    peter corey taylor guest

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    I would run a few bottles of injector cleaner or sea foam through it before doing anything else just to make sure the system was clean. Since the injectors were stuck, there is no telling what else is gunked up.

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