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2003, 2.0 318CI dying when idling - Aocal
Hi all

When my car is cold I sometimes have erratic engine idling followed by Engine stall. If I identify this intermittent problem before it happens I can apply some revs and stop it happening. But this isn't a solution as I actually need my right foot to brake sometimes!

The car had a similar problem last year which was eventually narrowed down to a Cam Sensor problem, I think this is totally different though.

I have had this problem for abour 6 weeks now, it seems to happen at least once a fortnight and only before the engine us up to temperature. Today I realised that I can reproduce the problem on demand. When the engine is cold and idling, if I dab the accelerator and remove my foot instantly rather than smoothly it enters this failure state. The engine goes into a state where it sounds rough as hell and eventually dies.

Any ideas? There are no fault codes in the system!

2003, 2.0 318CI dying when idling - Aocal
2003, 2.0 318CI dying when idling - Screwloose

Was that a cam sensor or a cam actuator that was changed? Is this the N42 B20A unit?

Might be worth cleaning and re-setting the throttle plate. An air leak through a split breather is a possibility; but I'd have expected a fuel-trim code.
2003, 2.0 318CI dying when idling - Aocal
Hi Screwloose,

It was definitely the cam sensor that was changed. That cured the problems I had previously.

Yep, it's the N42 Engine (Not sure about the B20A bit though?)

Yes, it's surprising I have no fault codes as when it dies it isn't pretty. The engine ends up in such a state the whole car is shaking! I would have thought a sensor somewhere would detect such unpleasantries!
2003, 2.0 318CI dying when idling - Screwloose

The misfire detection will see it; but it may need to persist for a certain period before it will flag a code and switch off the injector to the affected cylinder. [If it's just one.]

The fact that it doesn't attempt to increase the idle would indicate either a software glitch, or the fact that it's already at it's limit. Hence the clagged throttle housing suggestion.

Can your reader see manufacturer codes, or just EOBD?
2003, 2.0 318CI dying when idling - Aocal

Fault code reader is Just OBD, it's an E-Bay job! It does work though as it did detect the cam sensor fault.

If I am missing a load of BMW specific fault codes would the Engine Light come on and stay on, telling me to take it to a garage?

It's due an Inspection II in April. I'm not going Main Dealer this time, i've found a BMW Specialist. I'll get them to check i've got the latest Software
2003, 2.0 318CI dying when idling - Screwloose

It's quite noticable of late how EOBD codes have become sidelined to the extent that it's now an oddity to get a P0xxx code on many systems. Manufacturer-specific codes may not put the light on.
2003, 2.0 318CI dying when idling - Aocal
Someone else has suggested VANOS or MAF sensor? Anyone agree or disagree?
2003, 2.0 318CI dying when idling - Screwloose

Could well be the VANOS system - hence my question about cam sensor or actuator.

MAF is also a possibility.
2003, 2.0 318CI dying when idling - Aocal
I'm pretty sure it's the MAF Sensor!

Started the engine from cold and it was dying every time (I've developed a technique of killing it with the short sharp jabs on the throttle) Pulled the plug on the MAF Sensor and it didn't sound right but wouldn't stall. Plugged it back in and it was stalling again!

Does anyone know if it's an easy job to swap the MAF Sensor over?
2003, 2.0 318CI dying when idling - jbif
Does anyone know if it's an easy job to swap the MAF Sensor over?

I rate it as very easy. Try cleaning it first. See these threads
You can find many other illustrated instructions for different versions of BMW on similar forums.

It could also be the Idle Control Unit/valve if your car has one. Or the CAM sensor, or the Crank sensor(s), or the O2 sensors, or ...

Edited by jbif on 29/02/2008 at 18:33

2003, 2.0 318CI dying when idling - Daemon Taylor

I had a bad case of rough idle on my bmw 318 ci. Had it in the garage 3 times and each time they told me they had done something different. O2 sensor, vacuum hoses, crankcase breather pipe. None of them fixed it. I changed the vanos solenoids after doing a bit of homework, cured. Like a different car. And yes, I have changed garage.

2003, 2.0 318CI dying when idling - Phedor
I have a 2001 330i that has run once in 5 weeks. Every once in a while after I bought it in January (I live outside Detroit), the RPMs would bounce and it would shut off sometimes. Now it just won't stay on after it starts. The fuel pump/filter are both in good working order. Then I did some research about VANOS seals. I replaced them, and the car still stalls. I believe what happens is the faulty seals (look into these if you haven't already) cause other parts of the engine to break down more easily. They may just be the root of the problem. Does anyone have any suggestions for me? I'm thinking about replacing the intake camshaft position sensor. It could be so many things, but I'm really hoping that's what it is.
2003, 2.0 318CI dying when idling - Screwloose

If changing the seals made no difference; then maybe widen the testing a little. How long does it run for after starting?

Have you read the fault-codes or had the live-data examined - something is changing between running and stopping. What's the fuel pressure like? Is the cyclone breather split and leaking air into the inlet?
2003, 2.0 318CI dying when idling - Phedor
It runs for as short a time as it can. If I step on the throttle, it'll stay on but really wants to shut off as soon as the rpms drop. There are no fault codes from an OBDII from autozone, but the Service Engine Soon light had been coming on and off for a couple months. As for any cracks, I have noticed none. When the car miraculously started a few weeks ago on a sunny day, I took it out for a drive and it was great. I'm definitely leaning towards camshaft sensor issues. It sounds like similar problems to what Aocal has been experiencing. If I unplug it and try to start, will this change anything?
2003, 2.0 318CI dying when idling - Screwloose

OBD-II readers are now virtually useless - nearly all the useful codes will be in the manufacturer-specific section it can't access.

So it will stay running, but will not idle? That's massively lean or a huge air leak. Does running it with the MAF disconnected make a difference and set a code?
2003, 2.0 318CI dying when idling - Aocal
Hi Phedor

Did you fix your problem? Mine is at the garage today for an Inspection II, he said while the car was in bits it's easier to check some other stuff, he mentioned air leaks. I'll update tomorrow if mine is fixed and if so what the problem was. I'm not to optimistic though.

It's been a while since you posted but in answer to your question, I have unplugged cam sensors, MAF sensor etc, this puts the default value into the ECU, if this fixes your problem then obviously the sensor you have unplugged at the time is to blame.
2003, 2.0 318CI dying when idling - Aocal
Well, good news at last!

My car had the Inspection II at the BMW Specialists and they said that they did all the usual diagnostics but nothing came up (same as BMW had stated on the last 9 or 10 occasions).

However, since the service the problem has disappeared. So, an Inspection I didn't cure the problem, then the Oil Service didn't cure the problem but and Inspection II has removed the problem? So whoever knows what the difference is between an Inspection I & II holds the answer to the problem :-)

He did say my air filter was filthy, that's probably due to a lot of time spent on the motorway.

It was obviously something pretty basic, clogged fuel/air filter or dodgy spark plug or something. Shame BMW couldn't fix it over 12mths of hell. I've actually benefited from the BMW warranty running out and then going off to an independant. At least I haven't conked out pulling out on a lorry since.
2003, 2.0 318CI dying when idling - Aocal
Grrrrrr!! After a few months of pleasant motoring and begining to have my faith in BMW restored it has started happening again! Pulled out of work last night and had virtually no power.
It was really cold last night (Yeah I know it's August) it was 14 degs C.

Does anyone know of /recommend a DIY style 'plug in' I can get off E-Bay or somewhere that I can plug in, reproduce the fault, then analyse the data later to see why i've got no power at these intervals?

I've got an OBD II fault code reader but without a fault code that's a bit useless.


2003, 2.0 318CI dying when idling - Dr.J

I drive a E46 318i and my car had similar problems - It stalled when cold and had no power until the engine temp came up to normal. I took it to BMW specialist and he replaced the thermostat which solved the problem on the stalling but the car still had no power when pulling away... They then removed the catalytic converter - which becomes blocked over time and increases pressure on the wrong side of the engine. This also didn't help much for the power loss and flat spots. The BMW specialist recommended replacing the Air Mass Meter to correct the problem - also no fault code because the meter hadn't failed completely. However, when I took the car to have the air mass meter replaced, by another mechanic, he discovered that a pipe, branching from the air hose after it has passed through the air mass meter housing has slipped off. Before we replaced the air mass meter, which is quiet expensive, he replaced the pipe and I took the car for a spin - it was fixed! The car had masses of power, so much so that the traction control came on when I powered through a corner!

So, I recommend that you inspect every air hose, as this is apparently a place where any weak spot (such as a loose pipe, tear etc.) can escalate into massive power loss and engine failure.

Good luck!

2003, 2.0 318CI dying when idling - Aocal
Hi Dr.J

Thanks for your message. I wish i'd logged in earlier because I'm now going through the process of buying a new car. I've had almost 2 yrs of cutting out and the car has spent weeks in BMW dealerships and specialists but no one could fix it.

I'll have a look for loose pipes before I hand it over - just out of curiosity!

2003, 2.0 318CI dying when idling - dwjb
Hi Phedor,

I have a similar rough idle problem on my 328ci (1999). Generally, immediately after starting it's ok and then after the cold-cycle completes - the revs drop rhythmically (almost dying) and it jumps back into life revving to about 1500 then settles - this repeats.

I also read the forums and decided to replace the VANOS seals. This hasn't fixed the problem. I was also considering next replacing the camshaft position sensor. When it's rough idling, unplugging the camshaft sensor does settle it down, but then I wonder whether the ECU just goes into a 'defaults' setting if and when any critical sensor is unplugged.

Did you replace the CPS - did it do the trick?


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