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Z3 1.9 (M44) startling engine stalls while driving

Discussion in 'E36/7 Z3 (1996-2002)' started by Teddy, Jun 22, 2008.

    Teddy guest

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    Here's my dilemma:
    Basically, I experience abrupt stalling w/o consistent or advance clues. Some have suggested my car has an "old/poor" gas problem that has messed up the fuel pump, filter, etc. etc. It also acts electrical - like someone unplugged the engine and everything ceased. It was very startling when it first occured. This 1.9 engine, 1998 Z3 has been perfect for over 8 years. Like others I've read about, it too has never been driven in wet weather. 22K on odometer, everything near mint.
    The car was parked in Oct. of '07 just like every other year. I had approx a quarter tank of gas; no Stabil or other product used (unfortunately). First time out in May, stall problem occurs; both while driving and stopping. Now, car will backfire (CEL comes on) and quits (unless revved) on start-up; easy driving (all speeds); and during accelleration between shifts. But then again, there are small trips with no problems. MPG is presently at 26.3 @ 70 mph - seems ok but should be better?.?. To date, ran two treatments of Techron with two gas refills. Also, used one small bottle of dry gas agent. Cleaned plugs (little brownish/dusty color, with some carbon around top of threads. Also clipped a few vacuum/rubber hoses at tips (top side only). Unscrewed some connectors to check for oxidation (very slight if any). I'm cautious about clearner -but intend to do. I did change fuel filter - noted much less restriction as I blew through new and old. Also changed o-ring on camshaft position sensor (oil leak has stopped).
    If the car does not rapidly drop/stall-out on starts, I am able to drive for about 8-10 minutes before the problem becomes evident. Recently saw some carbon spatters in tail pipe (has always impressively clean). Rubber gasket around locking gas cap is lightly wet w/gas. This thread is current (7/17/08). I have posted individual threads on forum as part of my DIY efforts. Thanks for tips. All suggestions will continue to be welcomed. I will share the end of my journey. I believe in prayer - send one my way if so inclined.

    J B Lansing guest

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    teddy,
    When the problem occurs, does the engine just quit; or lose power (the revving and shifting comment sounds like the latter). Have you taken it to a BMW shop? They can usually run a diagnosis and see the history of any engine problems.
    J B

    Teddy guest

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    J B,
    When the car was taken from storage this spring, it started right up and drove fine for a few minutes. Suddenly it quit (more than loss of power) as I was accelerating in 2nd or 3rd; then smoothed out; then quit, it also needed revving a stop light -(I took it home and parked - not a enjoyable drive).
    Since the new gas, the addition of Techron, and a long freeway drive, the "quit" symptom has not happened again.
    Latest= car backfires and stalls on start-up. I'm changing fuel filter soon. If problem continues, I'll see a tech. I do, however, enjoy the info swap before I do anything (car or home).
    Thanks,
    Ted - Rochester

    J B Lansing guest

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    Hmm.... I just had similar symptoms with my sons old Jetta that had sat for a couple of weeks. Turned out a mouse had built a nest on top of his air Cleaner! A long shot but might be worth a look
    J B

    Teddy guest

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    Didn't see a mouse. But I did look (lol).
    Today, 7/18/08, after driving for about 15 minutes of mixed driving, I had one episode of stalling. I pulled into plaza and shut car off. I spent about 45 minutes shopping. When I started the car back up, the car "did-its-thing". I mildly (4-5K rpm) revved the engine each time it started to quit (5-6 times), then drove it home problem free.
    HERE ARE SOME FORUM TIPS TO DATE:
    -backfires mean unused fuel in hot exhaust (mine backfires cold or hot)
    -poor fuel due to 5 months of storage may have messed with fuel pump
    -quit pampering the car; it was meant to be driven hard
    -camshaft position sensor (I changed o-ring but it looks like the leak is back---may be on to something)
    -use techron and burn top tier fuel
    -some say I should burn correct octane (89 for my car); others say 93 oct. such as Shell V-power. One member said he drives 80 miles each day and found he got 2-3 more mpg with 93 Shell. Seemed like reliable info since he tests it frequently with diff fuels. I will try anything but I'm not sure I want to be posting a free commercial.
    -need codes, need codes, need codes, .........
    -fuel filter (changed it with Bosch ?.?.?.)
    -idle control valve was problem on early M44's
    -I have only read one thread (diff forum) where a member said after months of investigations on his Bimmer, lots of diagnostics, lots of $$, he corrected a rough idle problem after cleaning the pins and receptical on a air flow meter. (wouldn't that be nice)
    -gas cap problems can effect driveability (dealer said it would throw a CEL but not affect performance)
    I'LL KEEP YOU UPDATED. Please respond if something comes to mind

    InsomniAlex guest

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    My Z3 had some stalling issues also, but no backfires. I'd drive a bit, then it would just die. I'd be able to start her up again, but there would be a noticible loss of power. It ended up being the camshaft position sensor. I had that fixed, no more problems - at least not with the stalling.

    J B Lansing guest

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    I think you fail to realize the power of BMW's computer diagnostics. As an example, when my 2000, 2.8 was plugged in they could tell I had an intermittent seat belt connection and that I had pressed the brake and accelerator at the same time on three different occasions. (I would like to say I was practicing Heal/toe, but it was just my big feet). The point is they will see intermittent problems even if the car is running perfectly when you bring it in. The system is VERY sophisticated. Check your local CCA chapter's news letter. The Boston chapter runs free tech sessions at local BMW dealers where you get a tech for an hour to go over your car ask questions and plug in.
    J B

    Teddy guest

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    JB
    You are right. I respect the capability of diagnostics and have surrendered to this step. I've appreciated your input on other posts. I'm using this forum to learn. It's just me. I have also read numerous threads that go something like this, "code read o2 sensor; changed part; ok for week; CEL back on..." I see this a lot (not just o2 sensors) and some folks have spent some serious bucks and problem still exists. If it makes any sense to anyone, I just don't like taking a car to be repaired without background. The first BMW mechanic I called said it may be fuel pump due to storage/fuel. When I learned the cost, I felt compelled to try additives and watch for patterns, asked q's, and then read forums. Dealers are simply outrageous for repairs. I stopped a guy driving a Z3 and asked if he had any probs. He said he did see a CEL (no performance probs), took it to the dealer, they changed a sensor, it costs $800. Basically, I am scam-leery. If a mechanic replaced a $20 fuel filter or $200 pump (huge labor costs), I wouldn't know the difference unless I stood there and watched.
    Regarding the local chapter route, that sounds great (something like a forum w/o the scanner). How do I reach a local chapter? I live in Rochester, Mich (S.E. Mich). Can you send me a internet address?
    Thanks, Ted
    PS: Thinking about this another way, if I would have taken this car in at first symtoms, I wouldn't have had the opportunity to meet some very considerate BMWcca members. This is all car talk to me (social and technical) and I escape with car tinkering - much like the golfer follows a little white ball.

    Teddy guest

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    Alex,
    Who read your code for cms? How much did it cost? Did you observe the work or do it yourself? I heard the upper intake has to be removed on a 1.9 - gets a little more complicated than just two connections.
    Sorry for all the q's, but did your stall happen while starting, stopping, and driving (even while cruising down the highway)? Was the driving smooth at times?
    Ted
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    mooseheadm5

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    Very unlikely your problem is caused by the fuel pump. Find an independent shop with an Autologic. They can scan it just as well as the dealer. To replace the cam position sensor, I believe that you need to remove the upper intake (very easy and the gasket is reusable.) There are 2 11mm nuts (I think, maybe 12mm) that hold the front and back to brackets. You do not need to remove them entirely, the brackets are slotted. Then there are 3 fasteners where the upper and lower intake meet. Usually stalling at idle is caused by a vacuum leak or a faulty injection component, such as air mass meter, idle valve, etc. If you scan the car, it will usually tell you what ails it, but do not fall for it if it tells you oxygen sensor. That usually just means that the mixture is off due to a vacuum leak or bad air mass or some such problem. To find out if there are any codes, take it to Auto Zone or Advance and they will tell you what the OBD2 codes are. To find out if there is a vacuum leak, you can spray carb cleaner at various parts of the engine while it is running. Pay attention to the intake boot, the idle valve hoses (these are prone to rotting away) and the breather valve which is in the firewall side of where the intakes are bolted together. If the car is running at idle and the idle picks up at any time while you are spraying, you need to try to narrow down the source of the leak. BTW, do this at your own risk, because if you spray it into the alternator you may accidentally ignite it. I bear no liability. Buy a Bentley manual and learn to fix it yourself or don't complain about mechanics. Find a good independent that you can trust. Stop storing your car and drive it. Letting a car sit is about the worst thing you can do. Between fuel going bad, mice eating your wires, sticking fuel injectors, mildew, etc, just drive it once every couple weeks or so. Post in the correct forum and don't split up your posts when they deal with the same problem. I have only read this thread and do not have time to search out your other ones. It makes it difficult for us to help you. Also, not to sound like a jerk, but I work two jobs, one if which is getting paid to fix BMWs and will reply to posts when I have time if I feel like it. You do not need to email me to coerce me to respond. Now get the car scanned for codes and do a vacuum leak test and report back. I will be notified when you post.

    Teddy guest

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    Thanks much Paul. I will stick with this thread. As a noob, I didn't know any better.
    Also, I wasn't aware that BMW mechanics responded - - sorry if you were offended in any way. By the way, I think you were recommended. Otherwise, I would not have emailed.
    Leaks and codes it is..

    Ted
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    mooseheadm5

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    That's OK. Gotta set the limits sometime. Anyhow, do the tests and report back.

    incredibletulks guest

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    We own a 97 z3 brought from Atlanta to Eagle, CO. After a week of daily driving (200 mile approx) Check Engine light came on & it started running roughly. Could the change in altitude (we are at 6400 feet) be a factor? Could pulling the battery ground wire & resetting the computer help? Any suggestions would be greatly appreciated.
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    mooseheadm5

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    It is possible that the change in altitude has caused a problem. The car has "adapted" to run at a lower altitude. Make sure you have your radio code and go ahead and unhook the battery with the key out of the ignition so you do not cause EWS problems. Wait for a while, hook it up again and it may readapt. If it does not, you need to investigate why the check engine light is on, because it could be literally hundreds of reasons.

    incredibletulks guest

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    Thanks a lot. If it doesn't work, we will take it to a local shop for further investigation. Our Membership Dues have already paid for themselves...Thanks again.

    incredibletulks guest

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    Thanks again, Paul. Pulled the battery cable, and everything seems to be back to normal, with no CEL.

    pathines guest

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    Glad you cleared that up. I have a Scantool that helps a lot with basic diagnostics, the Equus 3130 model. Not nearly as thorough as the AutoLogic (which my local independent has), but affordable.

    incredibletulks guest

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    We ended up having to replace a bad injector. A scan tool is on my shopping list. Thanks for the feedback.

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