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Discussion Starter #1
as the title says, every now and again the car will stall as i take off from a stop.
once the car stalls, after i get it going again the power delivery is really weak, and doesnt even "kick-down" when i put the foot down.
any ideas as to what this could be?

note: it only happens maybe once a week. other than that, the car drives normally?
any advice would be appreciated
 

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as the title says, every now and again the car will stall as i take off from a stop.
once the car stalls, after i get it going again the power delivery is really weak, and doesnt even "kick-down" when i put the foot down.
any ideas as to what this could be?

note: it only happens maybe once a week. other than that, the car drives normally?
any advice would be appreciated
Definitely have some sort of problem in your fuel delivery/engine...sorry for the poor reply I'm very tired right now.

As for the kick-down, it can't engage when you're in 1st gear. What gear would it drop to? This may be the problem, I know when I first had my car I would kick it down and it would feel like it was gonna stall. (never did though)
 

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Discussion Starter #4
Definitely have some sort of problem in your fuel delivery/engine...sorry for the poor reply I'm very tired right now.

As for the kick-down, it can't engage when you're in 1st gear. What gear would it drop to? This may be the problem, I know when I first had my car I would kick it down and it would feel like it was gonna stall. (never did though)
travelling at about 60km/h, car would be in 3rd id say. it usually kicks down, but when this problem is occuring, it just revs out till it hits 6k where it will change. also the acceleration feels as though the gas is only half depressed..
 

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as the title says, every now and again the car will stall as i take off from a stop.
once the car stalls, after i get it going again the power delivery is really weak, and doesnt even "kick-down" when i put the foot down.
any ideas as to what this could be?

note: it only happens maybe once a week. other than that, the car drives normally?
any advice would be appreciated
How long has this been going on? I'm thinking if it's been a while, then maybe not fuel pump. I know they often fail intermittently before they fail, but they fail. Not saying it isn't; just saying what I think!

Fuel filters can get so ignored because they're hidden. If you haven't changed it in say 4 years, or ever, I'd consider that.

Bad gas if just a recent thing...clogged injectors if you never use Techron.

And then, consider what I was 'really' thinking...air leak. A crack that opens up under throttle...your fuel/air mix would be the same as if you had low fuel supply (pump,filter, injectors), just you have more air than the car knows about.

Good flashlight (you have the xl50 at Australian Home Depots? ), inspection mirror...specifically inspect the elbow on the lower intake boot, though it could be a leak anywhere after the maf.

Good luck...hope this helps!

Doug
 

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You can check the fuel pressure from the valve under the left hand engine cover...sitting in car.

Check this, but I think it should be around 50 psi.

Actually, that makes me think of the fuel pressure regulator. On later models than mine, it's built into the fuel filter and I think the vac hose that controls it comes from the F tube off the upper intake boot. Check that line for a crack or weak/dicey connection...the F tubes crack a lot it seems!

You're looking for a 'bicycle/tire valve' sticking up where I said. You put a pressure gauge on it.

As far as testing fuel pump for function...not so sure. Usually the test is listening to hear the pump. You obviously have a pump that's working (maybe somewhat only).

I'm still 'feeling' fuel filter/largish intake leak. Search fpr and see if that's associated with your symptoms.

Also, use advanced/title search and enter your symptoms as keywords...maybe 'stalling' and 'throttle'?
 

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Discussion Starter #9
over the weekend ill have to have a proper look thru it.
does anybody have any pics of what im looking at? first bmw so pretty new here.

just now, my dad took it out for a drive and all was normal again?
btw, im under the impression that its when the engine is started warm. this always seems to happen after i turn it off after a drive, start it back up again within half hour and then it seems to hapen. any thoughts
 

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Is the SERVICE ENGINE SOON light on, or does it come on at times other than when the key is set to RUN, but the engine is not running -- that is, is the SES light on while the engine is running?
 

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EXACT same thing is happening with me. when ever i pull off now im hesitant to think it might stall. so i already have it in steptronic so i can downshift to 1st if i need to.

like you said though. if i try to put the gas petal to the floor the engine does nothing. just continues the same way it was before i tried to go faster. i gotta down shift when i get on the highway just so i can get up in speed in time....

everyone said the exact same thing to me when i posted bout this.

checked fuel pump and any tars in the air intake.

nothing.....

now im lookin toward the vanos valve. but idk 100% if that could even be it. but i hear u lose alot of power in the lower RPMs when they start going bad.

next im going for new fuel injectors and spark plugs seeing i havent changed them since i bought the car.

hope we both find an answer
 

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Discussion Starter #15
no ses light at all, no unusual lights whatsoever. i have a faulty engine oil sensor, so the light comes on for the first 30 secs of start up but goes away after that.
car is currently at the mechanic, getting scanned for codes. hopefully this gives something of use.
 

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Discussion Starter #16
EXACT same thing is happening with me. when ever i pull off now im hesitant to think it might stall. so i already have it in steptronic so i can downshift to 1st if i need to.

like you said though. if i try to put the gas petal to the floor the engine does nothing. just continues the same way it was before i tried to go faster. i gotta down shift when i get on the highway just so i can get up in speed in time....

everyone said the exact same thing to me when i posted bout this.

checked fuel pump and any tars in the air intake.

nothing.....

now im lookin toward the vanos valve. but idk 100% if that could even be it. but i hear u lose alot of power in the lower RPMs when they start going bad.

next im going for new fuel injectors and spark plugs seeing i havent changed them since i bought the car.

hope we both find an answer
sounds pretty similar if not identical to my situation.
does this happen all the time for you though? mine is on off maybe once a week
 

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After your car stalls, in gear, your transmission is likely going into safety mode, until the car determines it is safe to exit safety mode.

Diagnosis and suggested repair tips:
-Get your BMW specific codes read, record them, clear codes.
-Drive car, attempt to recreate conditions.
-Check codes again, see what has returned.

I suggest paying attention to codes indicating failed engine position sensors, misfiring, and fuel trim values. Fuel trim can indicate vacuum leaks, causing lean condition and misfires. Failed sensors can disrupt injection and ignition firing, also causing misfires.

From hear either replace indicated faulty sensor or locate vacuum leak and replace leaking hose.
 

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Discussion Starter #18
After your car stalls, in gear, your transmission is likely going into safety mode, until the car determines it is safe to exit safety mode.
would safety mode then have any effect on the car stalling thereafter? it seems that when this is occuring, it usually WILL continue to shudder and stall if i dont accelerate quick enough
 

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I had the exact same symptoms a few years ago and it ended up being the intake camshaft position sensor. About a year later the exhaust camshaft position sensor went bad as well. I believe it is very common on e46's and should be throwing an SES code. If that is your situation there are a ton of DIY's on this and is a very easy fix. Sensors are about $100 each (1 intake, 1 exhaust) and only buy OEM on these. I have seen plenty of posts about replacing with Febi's or non-OEM and only to have it fail after a few thousand miles
 

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I had the exact same symptoms a few years ago and it ended up being the intake camshaft position sensor. About a year later the exhaust camshaft position sensor went bad as well. I believe it is very common on e46's and should be throwing an SES code. If that is your situation there are a ton of DIY's on this and is a very easy fix. Sensors are about $100 each (1 intake, 1 exhaust) and only buy OEM on these. I have seen plenty of posts about replacing with Febi's or non-OEM and only to have it fail after a few thousand miles
I bought mine from OEMBimmerParts.com for $77 after express shipping. I didn't buy "BMW Brand", but I bought the "OEM", which they say is the exact same thing as the "BMW Brand" without the BMW logo. :dunno:
 
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