BMW 3 Series cutting out

Intermittent faults like that can be a nightmare to diagnose .Was going to suggest idle control valve / throttle body for engine cutting out but that shouldn't cause it at 70/80 mph .Usual suspects for misfire or flat spot can be engine coolant temp sensor , coil pack / coils , leads ( depending on year of car ) ,plugs etc. etc .But they normally show up on diagnostic check .Best I can suggest to help , hope you get it solved .

thanks your reply whittingehame. I have recently rplaced 2 coils which failed. The sym,ptons where entirely different - this problem is so frustrating because it does not show up on diagnostics. But thanks anyway n regards - so if there is still oneone out there.....

Few suggestions from BMW forum on same problem ,

14-02-2009, 10:35

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Location: Middlesex
Posts: 11,161

You need to read the codes using a BMW specific code reader, as other readers may not show the problem. From the sounds of the problem you are having, it could be the camshaft sensor, but don't disregard a split vacumn pipe or other air leaks in the vacumn system. Start checking the throttle boot hose, just after the MAF.

and


31-05-2010, 00:56
I had the same thing within hours of buying my car a few weeks ago. Issue with mine turned out to have been the crankshaft sensor. I'm told that the sensor can sometimes act a bit erratic causing cut-outs, etc, and then work fine. Mine was cutting out for a few hours, and then after a journey on a recovery truck ran sweet as the following morning. Diagnostic revealed crankshaft sensor was the problem so got it changed. Touch wood, she now seems fine.

and

Check the inlet pipework after the maf for any signs of wear .

Thanks all for your support - assuming its the crankshaft sensor is it dificult to get at and replace?

Many thanks

It isn't an easy job , best left to garage .See here ,

http://www.bimmerforums.co.uk/forum/f18/2002-318i-n42-crankshaft-sensor-t61462/


2002 318i N42 crankshaft sensor.

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I am due to change my crankshaft sensor tomorrow due to the usual cutting out every now and then etc that is associated with a failing crankshaft sensor.
My question is this.
Has anyone changed one on the N42 and can give me a few pointers of what im up against. I.e what tools i may need and what to take off to get to it.
I have a good socket set and a set of torx sockets so im fairly well preppared.

Please dont confuse this with the easy to get to get to sensor on the M43 etc as i know the inlet manifold definately has to come off to gain access.
Cheers in advance.


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#2 09-10-2010, 00:33
crespo
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Make of Car: BMW
Model of Car: 318i se
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Found this post while searching the net. I thought i would post it here incase anyone else is going to attempt it.


It is a fairly long job, took me several hours but being careful helps. You need a torque wrench, a set of common sockets and spanners, a set of 1/4" drive sockets, a set of hex bits, and a set of small-size torx bits or keys. A lot of stuff comes off, so have a clean bench to put it all down on. You really need to have a good manual such as TIS or the Haynes manual, I have both and they were both useful. You have to get under the car so need ramps too. First clean the top of the engine well to remove dust etc to avoid it going down into the injector holes and the intake ports. Depressurise the fuel tank to avoid spraying petrol around when you disconnect the fuel pipe. Also disconnect the battery!
Generally a straight-forward job with a few awkward bits.

The whole intake manifold has to come off. Take off all of the air intake assembly and all of the stuff above the rear of the motor, which is the micron filter housing - looks daunting but is fairly simple. The hardest part I found to be removing one of the screws which hold the intake manifold on to the manifold support bracket, because my car has air conditioning (maybe you don't need it in your part of the world) and the compressor gets in the way. There are two screws, the one at the back is easy since you can see it from under the car but need a very long socket extension to get the torx bit up to the screw. To get it back in later use a magnetic bit holder or tape it on with sticky tape. The front one is a b*gger with the aircon compressor restricting access from below, so you have to do it from above and there is almost no room below the screw to get the torx bit in and turn it. It helps to have very small hands and my neighbour's daughter was a big help! When replacing it I used a hex head bolt, since it was a lot easier to tighten from above, and would be easier to remove in future. If you don't have air it should be easy from under the car I think. Also, remove or at least loosen the dipstick tube to allow the manifold to come off and go back on more easily - the TIS manual does not show this.

The fuel injectors were a bit sticky but came off with gentle leverage with a screwdriver. The connectors are fiddly, and the Jesus clips holding them on can fly away! The manifold lifts off vertically but was sticky too. Check the port seals and replace if any suspicion about condition.

Replacing the crank sensor itself is easy (a bit of an anticlimax), just above the starter motor, the screw is Loctited in so needs a bit of a twist to undo.

Clean the surface around the head ports with a bit of kerosene if it is even slightly dirty. Don't wipe stuff into the ports.

Replacing the manifold, take extra care to have the port seals securely in place in the manifold or you will have to do it all over again. ie they can fall out as you put the manifold on. But they do hang on in the manifold pretty well if you put them in carefully. If they don't then get new ones. Getting the manifold back on is almost impossible if you don't loosen the dipstick tube. You have to put the manifold back on while holding the oil separator assembly on below it - it has to slot into place into guides on the underside of the manifold assembly, but it just seemed to slide into place easily when I did it. The TIS manifold says you need special tools to do this (Haynes does not), and I was worried about this but it was easy. Using both hands at front and back and holding up the separator to the manifold seemed to do the trick. Torque the nuts etc down.

Keep the injectors clean when replacing them, use a very small amount of silicone grease to lubricate the O-rings.

Replace the screws under the manifold support (see above for advice). After that it is easy. I was a bit nervous while doing all this because I kept imagining that it would never go again and I would have to tow it down to the BMW experts, but it went first twist of the key.

My car has been fine since I did this, which is about 1000 km or so by now.

Good luck with it.


The Following User Says Thank You to crespo For This Useful Post:
eforty6 (09-10-2010)

My thanks to ALL who have contributed - Had a good search for air leaks?vacuum pipes only thing found is small rubber hose 4/5mm x 50mm leading into maf unit (before maf) this hose was perished and have now replaced it but has made no differnce to cutting out (2 times)So i shall book the BMW in to garage for Monday and hopefully that will resolve the issue - Once again thanks all you have been very helful
R

i been having this prob wiv my bmw i changed the idle control valve but no diff , then had new mass air flow sensor now she runs like new with no cutting out or erratic idle

i been having this prob wiv my bmw i changed the idle control valve but no diff , then had new mass air flow sensor now she runs like new with no cutting out or erratic idle , dont buy a after market one tho they only last about a month

Have you had a look at this similar problem:

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