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Thread: 325i will not hold idle/Not Start

  1. #1
    Join Date
    Dec 2018
    Location
    Germany
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    338
    My Cars
    1990 E30 325i 4 Door

    325i will not hold idle/Not Start

    Hey guys,

    for the last few days, i have been testing the while ignition and fuel system according to the Bentley manual, in order to sort out the no start/hard start/low idle issues.

    Coil, cap and rotor are brand new, as well as spark plugs. Despite that everything is within spec according to the manual and the multimeter readings.

    Checked impulse/crankshaft sensor, got 500 Ohms, again within specs.

    TPS is brand new and adjusted according to manual (was my first suspected issue), both coolant switch and sensors (blue and brown plugs on thermostat housing) are new, and tested within specs.

    Injectors read a solid 15.7-16 Ohms across the board.

    I removed the fuel pump relay and jumped the pins, pump comes on. Without the relays and pins jumped the issue is still there, as with the relay plugged in.

    What i tried is removing the FPR vaccum line to the intake, the car fired up and idled. Despite 600-700 rpms COLD idle, it idled.

    I placed my finger on the intake vacuum port (where the FPR hose connects) the car died. Placed my hand on the FPR vacuum hose, no effect. Does this mean that the FPR is bad? New one from BMW is €187 with a 5 day order time, which means i can not return it if i do not need it. Online Bosch ones are going for a silly €225, i can get a PIERBURG brand for €65 or so. But i would like to run this with you guys first, i believe i tested everything except fuel pressure itself, i do not have any sort of gauge to hook up and local hardware stores do not have them (must order online and will take 3-5 days, great right?).

    Would like to hear your thoughts, i am leaning towards either FPR or AFM, i need to remove it and test the AFM properly for resistance (and the flap). But i used to get some sudden "cut outs" when partial or WOT last week (tacho did not drop to 0, which further pushes me towards fueling issue).

  2. #2
    Join Date
    Dec 2005
    Location
    corpus christi, texas
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    No e30s, again :(
    I would check the fuel pressure first

    - - - Updated - - -

    you can do an easy check of the fpr by putting the hose in your mouth and sucking on it and putting your tongue on the end. if it holds tight and doesn't lose a seal then the diaphragm is good in the fpr and its 99% still good. if you suck on the hose and get gas or it loses suction against your tongue, the diaphragm is bad and it needs to be replaced.

    those are pretty resilient though. I have had only one end up being bad over all the 15 years of e30s I have had
    No e30s again.

  3. #3
    Join Date
    Dec 2018
    Location
    Germany
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    My Cars
    1990 E30 325i 4 Door
    Okay, i will give that a try thank you, will report shortly.

  4. #4
    Join Date
    Dec 2018
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    Germany
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    My Cars
    1990 E30 325i 4 Door
    FPR is holding vaccum, no gas but small fuel vapour smell/taste (which is normal i guess).

    Only thing left now to check is the AFM and the flap, as well as the sensor on the spark plug wires for resistance.

    With the exception of actually having a gauge to measure fuel pressure, those two (AFM and plug sensor) are the only two items left to check. That and the DME itself.

  5. #5
    Join Date
    Dec 2005
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    corpus christi, texas
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    No e30s, again :(
    anyone near you that can let you test out your dme on their car? and your afm on their car? that's the easiest tests. if the parts work on theirs then its gotta be a wiring issue
    No e30s again.

  6. #6
    Join Date
    Dec 2018
    Location
    Germany
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    My Cars
    1990 E30 325i 4 Door
    I'm the only E30 in my town sadly.

    I shall be testing the AFM tomorrow, need to remove the front box that holds the filter to access the flap.

  7. #7
    Join Date
    Dec 2005
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    corpus christi, texas
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    No e30s, again :(
    why? you can check the resistance of the wiper through the pins.... oh nevermind, I know why, so you can move the flap. I got it
    No e30s again.

  8. #8
    Join Date
    Dec 2018
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    Germany
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    1990 E30 325i 4 Door
    You are correct, i can access the flap from "behind" where the intake boot is, but i figured to remove it and seperate the filter box for more accurate testing.

  9. #9
    Join Date
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    No e30s, again :(
    Yes sir
    No e30s again.

  10. #10
    Join Date
    Dec 2018
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    Germany
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    1990 E30 325i 4 Door
    AFM checks out fine, so does the air temperature sensor. Flap/Door moves freely without an issue.

    I am starting to run out of ideas of what to test or replace now, it cranks, fires up and dies.

  11. #11
    Join Date
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    No e30s, again :(
    So now it starts but dies as soon As it fires up? But with the fuel prussure line disconnected and open to atmosphere, it will idle?
    No e30s again.

  12. #12
    Join Date
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    1990 E30 325i 4 Door
    If i disconnect the FPR vaccum line, the car will idle and a few moments later it dies.

  13. #13
    Join Date
    Dec 2005
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    No e30s, again :(
    Thats weird. How is your idle control valve
    No e30s again.

  14. #14
    Join Date
    Dec 2018
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    Germany
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    1990 E30 325i 4 Door
    Got a new one, even switching back to the original makes no difference.

  15. #15
    Join Date
    Dec 2018
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    Germany
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    1990 E30 325i 4 Door
    Got some new cooling hoses from dealership, as well as a new main relay (white one) and a Bosch fuel pump relay (orange).

    Even if nothing happens, spare relays are nice to have.

    Also received new Bosch plug wires (which include a new impulse sensor and coil cap), i was thrilled since while removing the old wires, the coil wire was "hanging by a thread" and i thought that was the cause. Sadly, after the swap it made no difference, car still cranks, starts and dies right away.

    Will swap the relays and hope for the best, other than that i can pull the injectors and check them mechanically using a 12v battery for their operation.

  16. #16
    Join Date
    Oct 2016
    Location
    Los Angeles, CA
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    24
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    BMW 325i 1989
    hmmm, are there any stomp codes that appear? Battery also reading strong right? I had this problem and it was my cap and rotor. But you replaced yours.

    It's starts, which mean sparks are happening for awhile, then it dies. So something is cutting out the fuel, or electrical to the spark. The pulse sensor on coil 6 wire, is that connected to the correct input? I know there's 2 input thats go to the ECU same exact plugs right next to each other, I think one is for the crank position sensor, maybe those got swapped? I remember my car not starting when they got swapped.

    Or it could be either huge air leak, or gas issue. If you could get a fuel pressure gauge test and hook it up between the fuel rail and fuel filter, that would help eliminate fuel pump/fuel pump filter or clogged fuel filter.

    What happens if you pump on the gas and try to keep it idle, does it struggle? or just dies?
    Was this car working before?

  17. #17
    Join Date
    Dec 2018
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    Germany
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    1990 E30 325i 4 Door
    I can not start a stomp code on my car, for some reason.

    I replaced the cylinder head gasket 3 weeks ago, due to a crappy job from the PO's workshop. So i ended up getting a new timing belt kit, tensioner, all front engine seals, tensioner spring, tensioner pin, all new aux belts for a/c, steering, alternator, new ICV, new O2 sensor, new cap, rotor, coil, plugs, wires, new thermostat and seal, water pump, new crank bolt and washer, new intake gaskets and TB gaskets, new exhaust gaskets, crush rings, etc. Basically everything that came off when removing the head was replaced.

    Car ran great, till a couple of days laster at WOT i got a "engine cut off" experience. The tacho did NOT drop to 0 but the temperature gauge bounced a bit. I did replace the fuel injector o-rings and filters from an ebay kit i found. That maybe the cause, since the filters were red and the OE i removed were light yellow.

    All oils, fluids, filters etc were replaced. I also replaced the clutch in Jan, resealed the transmission, new guibo piece and redid the suspension (H&R springs and Bilstein HD sport dampers). The workshop that previously worked in this car did a horrible job in...well everything so i ended up re-doing everything the PO did.

    The PO replaced the FPR and the fuel pump a year or so before i picked up the car. Maybe the CPS is faults despite reading 500 ohms resistance or the injectors are clogged from those filters that came with the kit. I may remove the filters and run the car and see if it makes a difference?

  18. #18
    Join Date
    Dec 2018
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    1990 E30 325i 4 Door
    I replaced both main relay (white) and fuel pump relay (orange), as a cheap insurance. No change, now i am leaning towards a faulty CPS or FPR.

  19. #19
    Join Date
    Oct 2016
    Location
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    BMW 325i 1989
    If it worked before with the CPS and FPR, but it stopped working after adding the filter to those injectors, I'd try removing those filters first cause it wouldn't cost you anything. But if it worked with those injector filters, then it shouldn't be those filters, and since the FPR was recently changed, it shouldn't be the FPR. I really feel like the FPR is unlikely to fail, unless it was really abused with some bad gas or something or just a cheap FPR, but then again you never know. I'd say which ever you did last before the problem occurred undo that first. Then I would say check CPS next.

    One way to check that FPR is if you remove the vacuum line, do you have gas coming out? shouldn't have any gas coming out, or anything wet at all.
    Also make sure your C191 plug isn't corroded or any dirt or water is in it.

    Do you smell ALOT of gas at the exhaust when you try to start it? or smell nothing. Try taking out a spark plug out and seeing if it's wet or if you smell gas.

    I really hope you figure this out, I'd like to know too.

  20. #20
    Join Date
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    Had a chat with the PO yesterday, the FPR is a Bosch one and so is the fuel pump, both replaced at the same time in october 2018.

    I have pulled the FPR vacuum line, small fuel vapor odor but nothing too bad, using my mouth as a quick vacuum test it holds vacuum and nothing comes out.

    No real odd smells when cranking honestly, i shall be pulling those injector filters shortly.

  21. #21
    Join Date
    May 2007
    Location
    Maryland
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    89 325iX
    I have the same issue with my iX after I did a ticking belt and a bunch of seals and gaskets. Hopefully you figure out your problem.

  22. #22
    Join Date
    Dec 2018
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    Thank you, i hope so as well. So far it is either injectors, FPR or CPS.

    Tomorrow i shall be receiving a CPS, will swap that out first. If she still does not start, then i shall investigate the injectors and remove the filters.

  23. #23
    Join Date
    Dec 2018
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    Germany
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    My Cars
    1990 E30 325i 4 Door
    Replaced the CPS, the car cranks over and fires up much faster, but it struggled and died for a second never to start again.

    So now it is surely fuel related, either FPR, Fuel Pump or clogged injectors. I wish i had a gauge to measure fuel pressure on the feed and return to isolate what is the cause. I can pick one up from Amazon or Ebay for €25 i guess before spending €80 on a FPR or €100 on a Bosch pump?

    I shall be taking the injectors off tomorrow, weather is horrible (live in an apartment and car is parked outside).

  24. #24
    Join Date
    Dec 2012
    Location
    Grandview, MO
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    493
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    1989 Bmw325IC
    The auto parts store here will loan you a pressure guage. Don't know about there in Germany. Also you need the necessary components to tap into your fuel pressure line - usually a T, hose and clamps.

  25. #25
    Join Date
    Dec 2018
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    No one locally has that tool.

    I shall take out the injectors tomorrow, test one at a time for their function using the 12v battery and remove the filters.

    If that fails, i shall look into an Amazon or Ebay fuel pressure kit.

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