[r11co]

Hi folks. I'm hoping some of the great brains here can shed a light on the problem I am having with my 2005 registered N52 330i E90.

The car has 54,000 miles on it and I've had it for about two and a half months. The symptoms started 3 weeks ago when on one occasion the car briefly cut out and lost power at motorway speed (a bit scary!) I coasted the car towards the hard shoulder when it suddenly burst into life again. No warning lights or alerts appeared on the dash when this happened.

I was a bit concerned, but a few more days driving showed no further problems. Then maybe a day or so later the engine lost power briefly at slow speed but again burst back into life.

Then last weekend I was doing some work on the car that meant I had the doors and bootlid open for a while, and afterwards when I went to start it up the battery didn't have enough juice to turn the engine over. All sorts of warnings then flashed up (DSC inoperative, Tyre pressure initialisation etc) which I put down to lack of charge.

I gave the battery a decent charge and the car started, but since then the car has behaved thus - it will run and drive normally for 10 to 15 minutes and then the power delivery will become jerky and eventually the engine cuts out. Try to start the car and it will fire and then immediately cut out. Try to start it again and the starter spins and it doesn't fire (at this stage I am assuming that the immobiliser has kicked in).

Remove and replace key and the engine will once again fire and then immediately shut down.

Leave the car for 10 to 15 minutes and then engine will start and run normally but drive a mile or so and the jerkiness and eventual cutting out returns. Leave the car to cool for an hour or two and you are back at the 10-15 minutes driving time.

As a precaution I have since fitted a new battery (same Ah and CCA as original, and the car has no IBS monitoring so no issues regarding coding in a new battery AFAIK) as I was suspicious of the condition of the original battery when I got the car anyway (nearly 8 years old and survivor of 2 very cold winters), but this has made no difference to the symptoms described.

One other job that has been done to the car since I got it is that the fuel tank breather pipe has been replaced (the original was the unmodified type that leaks eventually due to rubbing against bodywork). The problem has only been apparent since that job was done, but I am doubtful that it is related (unless maybe it is a fuel feed problem, but that doesn't explain why only when warm).

Just after I got the first 'hiccup' with the car I ordered an INPA cable which unfortunately has not arrived yet, so at this stage I cannot comment on any fault codes, but if someone recognises the symptoms and can make some suggestions I'd be very grateful as I don't want to start randomly and expensively swapping bits.

Many thanks in advance folks!

[wallsmk2]

crankshaft sensor?

a read of the codes will probably tell you

[r11co]

Originally Posted by wallsmk2

crankshaft sensor?

Thanks for the quick response

Do you really think that would be related to warm running issues?

[wallsmk2]

Originally Posted by r11co

Thanks for the quick response

Do you really think that would be related to warm running issues?

seems to be the symptoms - engine dropping revs, cutting out, not charging the battery. I'll bet my dog on it

[r11co]

Originally Posted by wallsmk2

...not charging the battery.

I'm pretty sure the battery is charging fine - the low charge was cause by me having the doors open and the internal lights on for several hours I suspect.

[wallsmk2]

the sensors can be affected by temperature so could be. Read the codes to shed some light on it.

[r11co]

OK, so I don't have access to INPA yet, but I plugged in my ELM327 interface and used Scantool to read out engine ECU fault codes - there are none logged!

OBDFacile read the transmission module and again no faults logged?!

Any suggestions?

[r11co]

OK folks - finally got an INPA setup working. Fault code produced is P1383.

Incidentally, symptoms have now deteriorated to the car firing for a fraction of a second and then cutting out. Attempt to restart just spins the starter with no firing (I suspect that ignition supply is being cut by the ECU following the fault - remove key and replace and you get a fraction of engine firing again).

"2E77 Ignition Voltage Supply, P1383 Ignition Monitoring Malfunction"

Not very helpful unfortunately. Any ideas folks?

[Jat]

Long shot, but have you ever replaced the battery? I had issues with power cuts, and also steering lock symptoms, and it all came down to the Intelligent Battery Sensor that is fitted to the power supply from the battery. It did however show on diagnostics.

[doughboy]

AFAIK you do have to code in new batteries.

If the tank breather is defective a then a partial vaccum in the tank will starve the engine of fuel.

Take the filler cap off, is there a suction noise when you do so?

[r11co]

Thanks for the replies!

Firstly - the car isn't fitted with the IBS system (at least it isn't present on the battery terminal).

Secondly - I have been suspicious of the fuel system but I've managed to run fuel pump tests using INPA and they have come up OK!?

Edit - just tried starting the car with the fuel cap off, and then back on again. No vacuum in tank, and no difference.

[r11co]

Just a feed back on this problem, which turned out to be a water damaged DME unit (engine ECU). The bottom inch of the DME had been sitting in a bath of water which had gathered as a result of the drains for the plenum under the windscreen being blocked. Despite the DME being inside another plastic box which is supposed to protect it from moisture the water actually got in through the drain hole at the bottom of the box.

The water damage explains the strange behaviour and lack of meaningful error codes.

The bad news is I was facing a bill approaching £1500 for a new DME and programming. The good news is that I managed to get a used one set up for the car thanks to Jason at BW Chiptuning who transferred the data from my unit that had been for a swim over to a replacement - all done by post! Jason is a great guy - helpful on the 'phone and extremely knowledgeable, and he admitted this was his first attempt at transferring details of an MSV70 DME, but it was a 100% success and after 6 weeks of of head scratching the car is back on the road.

Credit also to Owen Ferry Automotive of Paisley who diagnosed the problem in the first place and was very tolerant of my determination to avoid having to fit a new DME to the car!

The money saved will be spending money for our summer holiday!