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Topic Review (Newest First)

  • 12-09-2011, 04:24 PM

    Final Update (for the archive)

    This is the first winter in a very long while that I haven't had any cold-start problems with the BMW, so I'm going to jump to a few conclusions and leave them for the archive, in case anyone else has similar problems.
    First: It was the corroded FI lead that did it. (In the engine compartment; with increased resistance.) I think that BMW tacitly acknowledged this problem by changing the FI wiring in the next model year to eliminate the wires outside the plastic harness-bar; in any event, cutting out the corroded length of wiring at the #1 connector and patching in a new piece has completely eliminated the cold-start problem. (We still live at 8500', and have already had a couple of sub-zero nights [things used to get hinky below 20 degrees], so the contributing factors haven't changed.)
    Second: The warm-restart problem is probably leaky injectors. I've gotten a new set, had them cleaned and balanced and am waiting for warmer weather (and a new [used] FI wiring harness) to replace the FI system. If that clears up the other part of the problem, I'll update this record.
    I travel a lot on business and consequently drive a lot of much newer rental cars, but I'm always happy to get home to my nearly-25-year-old 325. Thanks again for your interest and all the help (especially Geez Tech).
  • 07-01-2011, 12:33 PM
    On this one, I think I place a higher value on the trick that lets me get AROUND the starting problem than on the solution itself: The fuel-pump-relay thing really works, but the FI-harness-corrosion was never absolutely PROVEN to be the cause of the problem.

    One reason for my reluctance to accept the possibility that I've found a cure: The car is running EXACTLY the way it was before, meaning that it catches instantly if the engine is restarted within, say, two minutes of having been run, but requires 5+ seconds of cranking if it's been sitting for longer than that. I'd though that that was caused by old, leaky injectors, and was getting around to replacing them, but having a fuel pressure gauge in the system for so long showed a VERY slow (several hours) leak-down rate.

    I'm still planning to get around to replacing the injectors.

    And I'm planning to come down tomorrow, pick up a pit pass, and give you a call. BUT: This is your vacation - any discussion of my car is forbidden!
    See you soon -
  • 07-01-2011, 12:37 AM
    The 40-42 is close enough, it may just be the gauge. It is possible the plugs may hae still been a little fuel fowled and your relay trick helped let it run long enough for the engine to heat up and clean the plugs some once driven, I will say your #1 injector wire was the culprit.
    We are in Richfield,UT tonight, in Denver tomorrow night. Check your PM's and give me a ring this weekend.
    Good job on seeing this through and getting it fixed.
  • 06-29-2011, 12:51 PM


    I generally like to close out these little interludes with a report on what I've learned, for the archive, and a hindsight-enhanced look at what I could have done to get the whole deal over with faster.
    This time, though, I'm at something of a loss: aside from the #3/#1 blunder, there's not a lot I would have done differently, and - full disclosure, here - I'm not entirely certain that I actually fixed anything. (The wires from the position sensor came off in my well-intentioned helper's hand, at the outset, so replacing that item was sort of a necessity; the replacement part in currently installed in the car, so its used e-Bay provenance wasn't part of the problem. The distributor cap DID have a crack, and I've [briefly] considered re-installing the damaged part to see if it was functional [maybe later.] The corroded wiring at the #1 FI connector was the most serious fault I uncovered, but repairing it didn't immediately result in the kind of cause-and-effect renewal that you like to see in these cases.)

    It's hard for me to see how the fuel pressure regulator could be a part of the problem, GT: It has consistently yielded 41-42 psi readings, and was purchased (new) a year ago. It's still in the car, and engine is now starting on demand, without removing the fuel pump relay. (The ECU sort of re-booting itself?)

    To me, the best thing to come out of this experience (aside from having the Bimmer back) is the three-step diagnostic trick (create fuel pressure, remove the fuel pump relay, crank the engine): If it starts and runs for a bit, the problem is almost certainly in the FI system.

    So: A sort of disappointingly inconclusive resolution, but - What the hey - a hell of an improvement.

    See y'all next year!
  • 06-29-2011, 01:59 AM
    Buuuttt you are saying have over 40 lbs of fuel pressure? It should be a 2.5 bar system which puts it around 35 to 38 lbs with the regulator acuum line disconnected. How far over is it the 40 lbs?
    I hate to think this is coming back to a "possible" fuel pressure regulator, didn't you do this last year? If so was it new, used or aftermarket?
  • 06-28-2011, 04:42 PM
    its Josh
    congrads on getting the bimmer running again.
  • 06-28-2011, 04:03 PM

    AwRIGHT!!! ROAD TRIP!!!!!!!!!!!!!!!

    The trick with the fuel pump relay works!
    Now, all I have to do to get a loaf of bread is 1) Turn on the Bimmer's key to build fuel pressure, 2) Jump out of the car and pull the fuel pump relay, 3) Climb back in and start the car, 4) Jump back out and re-install the relay while the engine's still running, and 5) Climb back behind the wheel and drive to the Safeway.
    And this is a HUGE improvement!!!!!!!!
    All things are now possible (at least as soon as I put the radiator back in.) And I've GOTTA be getting REALLY close to having a totally functional car again!
    YEEE HAAAH!!!!!!!!!
    Vaya con Dios, GT!
  • 06-28-2011, 11:09 AM
    The fuel pressure gauge has been hooked up all this time and consistently shows a good, solid 40+ psi.
    Check your PMs.
  • 06-27-2011, 11:25 PM
    Yes very close, is the fuel pressure gauge still hooked up at this point? If not them lets get that back on until this is resolved.
    You are correct on the residual fuel pressure, when you first turn the key on the system gets pressurized. If you are then removing the relay then it is running off of that fuel pressure.
    Lets get the gauge back on and see what the pressure is doing.

    On a side note to a previous question, no the injectors will not stop when you mashthe throttle during your initial noid test. But they shut off if the engine was at a higher RPM when running when you let off the gas pedal complately until it reaches a certain RPM.
    Leaving in two days.
  • 06-27-2011, 07:49 PM
    I pulled out the FI harness and re-tested it thoroughly, twisting the wires and wiggling the connectors. The thing is solid: the connections at #1 are ugly and home-made, but all the wiring is totally functional.

    How about this: Crank the engine for a second or two to build fuel pressure; pull the fuel pump relay; then crank the engine until it starts and have a helper put the relay back in?

    What could go wrong?

    Anybody want to volunteer for the 'helper' position? (Hell, the relay is on the opposite side of the engine from the oil filler cap!)
  • 06-27-2011, 01:53 PM

    Okay, we're getting somewhere . . .

    . . . I'm not sure where, but we're definitely moving forward.

    I thought I'd screwed up the repair on the FI wiring, so I took it apart again but found no problem. I reinstalled the harness, reconnected the C191, and this morning I got up the courage to try it again.
    First attempt: Nothing - it turns over on the starter, but doesn't catch at all.
    Second attempt (noid light in #1 injector connector [hence, #1 injector disabled]: Still doesn't fire, but it seems to 'want' to catch - definitely different from first try.
    Third try (#1 injector re-connected and fuel pump relay removed [I'm not really sure why I tried this]): After 10-15 seconds of cranking, THE ENGINE FIRES UP!!!!!!! It runs (smoothly, amazingly enough, after all I've put it through), with normal throttle response, for 15 seconds or so, then dies (as the residual fuel pressure is exhausted?)

    It seems to me that this would indicate that 1) the problem is definitely with the FI system; 2) the engine is being OVER-supplied with fuel; and 3) I've gotten really lucky and haven't damaged the engine with my #3/#1 blunder.

    Okay: What's gonna cause a mixture problem? (I should be pretty well set up to test for a solution - at this point I've got a spare ECU and several extra coolant temperature sensors.) ( And speaking of coolant: There isn't any. I've still got the radiator out for easier access to the front of the engine. What the hell is that going to do to the signal the sensor sends to the ECU, and to the ECU's mixture determinations?)

    DAMN, but it was a MAJOR relief to hear that engine running again. Now, if we can get it to run for more than 15 seconds at a time.

    Instruct me, O Master.
  • 06-26-2011, 01:36 PM
    "On the FPR, you have it out of the fuel rail?"
    I removed the 'Fuel Pump Relay', not the 'Fuel Pressure Regulator', to disable the fuel delivery system, just like you taught me. When I re-installed the relay, the engine wouldn't start again, but I've got some ideas about the problem: I'll do some more work and get back to you.
  • 06-25-2011, 10:43 PM
    Hmmm, that is still strange it backfired through the crankcase though but dont do my suggestions at this time with the wires being switched.
    On that note, stupid question here, is the coil wire on the correct terminal? Big :)
    The distributer cap has the wire positions on it by the terminals, they are hard to see but they are there.

    On the FPR, you have it out of the fuel rail? Why?
    When you put it back in did you also reinstall the fuel pump relay? Or id you leave the relay out and it wouldn't start?
    Do you have a electrical schematic? If not do you have a Fax at the house? If so PM me or e-mail me the nuimber and I'll send Monday.
    This has been fun, no worries and your not an idiot.
  • 06-25-2011, 09:52 PM
    The explosive misfire was caused by the accidental swapping of the leads to #1 and #3 at the distributor cap, probably at the time I replaced the cap.
    I don't wanna talk about it.

    (Much) later: The engine now starts and actually runs on starter fluid (with the fuel pump relay removed); with the FPR in place, however, it turns over without firing up. I think the FI wiring harness is still screwed up; I'll pull it back out and stress-check it in the morning.

    Jesus, GT, I'm so sorry. You've put SO much time into helping me, and I've been such an idiot.
  • 06-25-2011, 06:18 PM
    Well that is interesting, now the long shot.

    I have seen this once before. Lets just say you had a over richness issue that "may" now be resloved. While the "problem" was happening there was too much fuel going into the cylinders and it has washed the oil off the cylinders and is now in the crankcase. The piston rings never seal perfectly, so it is possible for the fuel vapors to be in the crankcase and the ignition system cam light them off in a case like this because there isn't any oil to help seal the rings against the cylinder walls. make sense?
    It is very odd but I have seen it happen but yours is an extreme with blowing off the oil cap.
    If this has happened then you dont have enough compression to help the engine to fire since the rings aren't sealing.
    Did you ever do a compression check?

    Just to be clear, the harness is now measuring properly after your repairs?

    here is my suggestion:
    1. Change the oil
    2. Remove all the spark plugs and try to squirt some oil down each cylinder. Not a whole bunch, just a few squirts.
    3. Crank the engine with the plugs removed, just a little bit.
    4. Reinstall the plugs and see if she lights up.
  • 06-25-2011, 01:53 PM

    Anybody got a spare oil filler cap?

    I got everything re-connected this morning and tried to get her started. It cranked for about 10 seconds without really sounding like it was gonna catch.
    Then a backfire blew the oil filler cap into the weeds.
    I got no idea where it is.

    FOUND the sumbich.
    At least 50 feet away, and 20 feet up an embankment.
    Thank God I was working alone and didn't have anyone peering at that side of the engine.

    GT: Yeah, the FI harness was completely disconnected when I got those readings, and I was referring to the 12 pins on the 6 injector connectors.
    After the debacle this morning I pulled the harness off again, and still get good readings (what you described) at every FI pin. (Readings with the injectors and the C191 connected are, as you implied, pretty ambiguous.)
    And mine has 1 719 520 on a white band (there're a lot of other numbers, too, mostly illegible.)

    I think I'm gonna take a break now, and let anybody who has any ideas about that explosion check in. Please feel free to share your own backfire stories, because I haven't ever seen anything like this before, and I have no idea what it means.
    Nothing good, I'll bet.
    On the bright side: Now we know for sure that we've got spark.
  • 06-25-2011, 12:00 AM
    "ALL 12 of the FI pins show continuity ONLY to pin #5 of the C191." ??

    The C191 is only 7 pins, how are you getting 12? Or are you counting the 2 pins at each injector? If so and you have the harness out and not connected to the injectors then this is bad.
    If the harness is connected and you have the plastic cover off the harness and you are back probing the wires at the injectors then this why you have continuity on 12 wires as you are getting readings through the injectors. make sense?

    Pin 5 is the 12v supply for all injectors, it has a solder joint splitting from one wire to 6 between the C191 and the injectors.
    Pin 6 of the C191 is the ground side for 1,3,5 injectors and Pin 7 is for 2,4,6 injectors. same deal, one wire into a solder joint that goes from one wire to 3 wires.
    The solder joints are probably under the plastic cover for the injectors, they have a rubber type cap on them.
    There may be a silver tag on the injector harness, see if it has these numbers "1 719 606". Report back.
  • 06-24-2011, 12:18 PM

    Okay, we've finally, FINALLY, found something wrong.

    I've pulled the wiring harness to the injectors, and the red/wt lead to #1 is brittle, with bare wire exposed in several places, all the way back into the harness. ALL 12 of the FI pins show continuity ONLY to pin #5 of the C191.
    While I'm gonna hold off on celebrating until the little guy fires up, it seems to me that this problem definitely fits the symptoms.
    More later.

    Later: I've cut the faulty wire back beyond the damage, but I'm still getting the all-roads lead-to-#5 readings, so there's probably a short hidden somewhere in the harness or the connector. I'm not finding the part in any of the Denver-area yards; does anyone have any suggestions? - or a FI wiring harness they're willing to part with?

    Later still: I spent the first couple hours of the afternoon trying to find another FI harness, and the next 30 minutes fixing the one I've got. But, like every other element in this puzzle, the harness is yielding its secrets grudgingly: The thing that got it working was the removal of the rubber top cover of the C191 connector. There was no sign of corrosion and no foreign bodies, and I didn't even tug on the exposed wires: But the next time I checked, I got the correct continuity readings. (I'll be keeping an eye on this.)

    So: I'm going to solder in some replacement pieces of wire and re-test the harness; then I'll wiggle the wires into position on the engine and re-test them; then I'll hook all the wires up and test again. If all goes well, I'll be turning the key sometime Saturday morning, then turning off the engine and putting all the rest of the pieces back on.

    'Wish me luck' doesn't cover it: Pray for me, dudes.
  • 06-23-2011, 09:23 PM
    Before you do too much hunting make sure you are doing your checks with the harness "and" injectors disconnected as you will get continuity through the other injectors to the other pins.
    If not done already pull the boot back on both sides of the C191 to make sure you dont have corrosion of some sort causing a short between the wires.

    7 days until our trip begins.
  • 06-23-2011, 12:08 PM
    I really, really like that exclamation point, GT! Lemme see what else I can find out, and I'll get back to you later today.

    Later: The multimeter says I've got continuity between the brown/white lead of the #1 injector connector and ALL of the following terminals of the C191: Center post and two contiguous terminals on the ring (probably #6 and #7); no connection is indicated on the other 4 terminals. (The same is true of the red/white injector lead: It shows a connection to the same three C191 pins.)

    This can't be what the guys in Germany intended: I'm going to try to hunt up another FI wiring harness, and I'll be back as soon as I've found one.

    I'd say Thank You, but I'm not entirely certain that we're out of the woods yet. But if this thing ever starts, I'm gonna be all over you, GT.
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