Car stalling on cold start

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igeak691

Member
2003 BMW Z4 3.0i m54 112k miles.

Months back I would notice very very slight hesitation while rolling away in first or second gear after a cold start but didn't think much of it. Then one day I was with the wife driving off and we heard this clicking which was followed by me pressing in the clutch and listening, eventually the idle jumped around and the car stalled. Now, on any cold start, the engine will start up with no problem but after 10-20 seconds will become to idle very erratically. This erratic idle (which shakes the car quite a bit while its bouncing up and down briefly), before stalling, is always accompanied by a series of clicking noises, not like relays but at first I thought it sounded like the differential grinding, which I can hear between the two seats underneath the car. It may be coming from transmission, differential, or fuel tank.. but I don't think it is the transmission or differential because the car will still have problems in neutral. Symptoms have gotten progressively worse, and now on a cold start it will definitely happen. And now it takes a number of restarted before it doesn't stall.

I will get a video in the morning, hopefully the audio will pick up the clicking that occurs.

I have cleaned the IAC valve but that didn't do anything. I've thought about VANOS seals but it still doesn't explain why its always clicking underneath the car before the engine idle goes and stalls. I've thought about a fuel filter or fuel pump, which is my best guess right now but I don't wanna go down there and swap it out only to find out it wasn't the issue. What could possibly be causing that clicking before the stall?

Also, no check engine lights have come up.. nothing pending either..
 
Also forgot to add no amount of giving it gas will stop it from happening. Sometimes I tried holding the idle higher which didn't work. Tried driving away and hopefully being in gear would work but that didn't help either cause the car would start jerking very erratically like I was stepping on the gas and taking my foot off very quickly. Eventually no matter how much I press on the gas the car will stall.
 
Obviously try to get a code reader to see what fault codes there are, also check the air intake for vacum leaks there is a rubber boot on the throttle body which can split. Also try disconnecting the disa valve to see if the clicking noise stops many videos on YouTube show how
 
Like I said no check engine lights and nothing pending either. I checked air intake for leaks, and DISA looks in good condition along with IACV. The clicking is coming from the direction of the rear differential, so I don't think its the DISA clicking.
 
Sorry missed you had read the codes in your first post could it be the fuel pump I believe it is located in the tank you can easily check if its the disa just unplug it
 
I am leaning towards the fuel pump too or fuel filter, maybe a combination.. I plan on replacing both but I am just wondering what the clicking noise may be. You can hear it right around the 1:36 mark and around 2:00. The first time it happens it clicks a lot before stalling then it stalls quicker and quicker.

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To me the clicking sounds like the exhaust rattling/banging against something as the engines shakes and stalls. Very weird problem though :(
 
To me the clicking sounds like the exhaust rattling/banging against something as the engines shakes and stalls. Very weird problem though :(
 
Cars very smooth even with the clicking noises it isn't like a banging sound but right now I'm at a loss so I'll believe anything as long as it makes sense. I'm hoping it's the fuel pump and filter because it's likely need changing already at this mileage and I'm hoping it will also fix the fuel sender as long as it's the right one that's messed up on my car and not the left. Full tank still says 1/2 is annoying.
 
Sounds very similar to mine when it had a problem with the camshaft eccentric sensor (the sensor controls the variable camshaft timing). The clicking, popping and banging you hear is likely to be misfires and unburnt fuel igniting in the exhaust. A quick google of 'BMW eccentric shaft problem' will tell you even more....

The exact codes I had were P1017 and P1030. I understand you can get problems with the sensor or the motor, but problems with the shaft itself are quite rare.
 
Ah, thanks. That clicking noise was the oddest factor but certainly can be explained by slight misfires and unburnt fuel. Though I always thought that would be loud pops and bangs like when people do it on purpose. How would I go about tracing it without any codes to chase after? And would a problem like that only show up on cold starts with no symptoms after a couple of starts? Guess that means I'm also chasing down coils, camshaft position sensor, vanos, and a whole bunch of other possibilities..
 
Once everything is warm things tend to loosen up a bit - mine popped and banged like an old lawn mower until it was warm then was perfectly happy. Other than taking the whole thing apart, I don't know any other way than to read the codes. An OBDII reader is pretty cheap from amazon etc - you don't need a fancy one - ours is cheap and cheerful and helps in simple diagnosis even on Porsches...
 
I have an OBDII reader but it's not showing any faults. Here are two more videos from different angles, it's definitely something in the engine area like you said.. never heard those knocks in the car but it was pretty dramatic and unnerving. The first vid with the exhaust is the first startup. The second vid is the second startup. Definitely don't wanna keep starting it up now unless I've got it figured out.. sounds very scary.

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Would any engine have those knocking sounds when the revs drop so low before stalling? No matter how much gas I give when the revs drop, it doesn't help. Even when I keep the revs up at 2k rpm, eventually the rpms drop and then its like my throttle input doesn't make any difference to its course of action.
 
I would check air parth, maf, coils, plugs and then the fuel system including sender and rail pressure. I think you should be able to read off rail pressure using diagnostic software and perhaps throttle position too.

A visual inspection of the above would be a good start, connections etc and then failing that is get it to a garage for a more thorough investigation.
 
Agree with Marc-j.

It's something to do with the engine being starved of something - could be fuel, air, or 'ignition'. It's not firing on all of its cylinders... Hence - check anything to do with that - coils, fuel system, spark plugs, any other electronic gubbins that control any of the above.

It sounds just like mine did - it would start, then as it warmed up a bit, it'd cough and splutter, and if you could keep it going with tiny careful throttle inputs, it would eventually warm up completely and run ok. Ultimately it wouldn't even start smoothly - the final straw was when it sounded like an old tractor and needed nannying to get going...
 
A further clue to the fact it's not firing correctly is the unburnt/smokiness coming out of the exhaust. Not a happy engine.... and yes, it will rattle and shake horribly because there are ignitions going on at the wrong time, and most probably in the wrong place (in the exhaust system...). Not something to keep doing - unburnt fuel on the catalytic converter and lambda sensors could kill them (queue lots of cash to fix...) :(
 
Further update.. today, I tried looking at the injectors and fuel rail, check some vacuum hoses. Didn't really find much but car did same thing on first start, then it started and idled fine on the second start. It is pretty warm today compared to other days.. but I went driving, and cruising in fifth gear the car started to die again, like I was giving it gas but it was still dying. Eventually I pulled off to the side and when I let in the clutch the car died like it would've if I was at a stand still. Anyway, after a few startups it didn't happen again, and I also put some chevron fuel system cleaner in the tank. I'll be doing another bottle with the next fillup. What's surprising to me is that it happens when the car is "warm" now too. I think perhaps fuel filter related? Car gets starved of fuel intermittently I'm guessing, which leads to the misfires and knocking and stalling. Hoping the fuel cleaner will take care of it. If it does or doesn't I guess I still need to swap the fuel pump/filter assembly? Still very confused, but saw another thread on a forum (http://forum.e46fanatics.com/showthread.php?t=705131&page=4) very similar and it was fixed with a fuel filter.
 
If you can, get it to a garage to take a look. They might charge £100 to fault find but they'll have the right gear to get to the bottom of the issue and save you replacing something you don't need to. If you want to have a go yourself some more, get it on a BMW dis or inpa to get the codes off and read the vitals from the modules. Fuel pressure, air fuel ratio, mass air flow, injector status
 
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