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JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Monday 20th June 2011 quote quote all
I have a 2003 facelift 318i e46, when pulling out of a junction in first gear the car sometimes bogs down and I have no power, the revs won't rise at all and I virtually stop.
Sometimes it then jerks and then I get reduced power and can move on. Other times I have to turn the ignition on and off to get moving again.

It only happens in the morning when the car is cold and happens about half a mile from my house - I always know at which junction it will happen and it's the first point where I have to stop and then pull off in first gear. Any ideas what it could be, the car is well serviced with the last one being done two months ago by a local specialist.

I think this engine is multitronic (what ever that is) which my specialist says causes an increase in power above 3k revs and he did say they can be a bit lack lustre below this but something with my car is very wrong.

Any ideas what it could be? Thanks in advance

Barreti

5,597 posts

123 months

[news] 
Monday 20th June 2011 quote quote all
I had a y2000 E46 320 2.2 which had a similar sounding thing to yours, only mine was completely random and not just when it was cold.
I had it at BMW and BMW specialists, who either couldn't find a fault or replaced crank sensors (I think there are 2) as 'suspect' parts.

The problem was never found though and I sold the car because it drove me nuts and I thought it was only a matter of time before I had a serious accident because it wouldn't pull away from a junction without warning.

I did discover though that removing the key and restarting would most often 'cure' the problem.

JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Monday 20th June 2011 quote quote all
Thanks for the reply, having an accident is what worries me most. in the morning rush hour I could do with knowing that I can make a brisk exit from a junction without stopping across the lane like I did this morning!

aizvara

1,718 posts

53 months

[news] 
Monday 20th June 2011 quote quote all
I've a 325i, but had similarish problems early on in ownership - not so pronounced as your example, though. It felt more like a significant lack of power on occasion, rather than actually leaving me stranded.

I tried cleaning the MAF which did seem to help, it was also suggested to me that it was the traction control, and I may have simply got better at pulling away without triggering that (the tyres were pretty dire when I bought the car). Your case doesn't sound like traction, but I guess you could try disabling DSC just for testing.

JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Monday 20th June 2011 quote quote all
The traction control never activates and its's definately more of a power issue than loss of traction.

This morning I literally pulled out of a junction and had no power, I floored the throttle and the revs didnt move at all, no power at all, it didnt even jerk back in to life today and I had to turn the car on and off again.

Other days I have had just a lack of power, some days the car is sweet and feels lively, other days it is sluggish and doesn't want to rev or accelerate with any vigour.

Think I'll have to get it on a diagnostic machine to look for fault codes.
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Barreti

5,597 posts

123 months

[news] 
Monday 20th June 2011 quote quote all
Talk to the place who you will get to do the diagnostics. Ask them if you can leave it with them overnight and get it tested first thing in the morning.

They tried this with mine.

Also, I don't think the crank sensors are too expensive, about £70 apiece to have mine changed I think. It might be worth getting them changed.

One last thing, though it may be a complete red herring.
The day before I took mine in for the trade the fuel pump failed.
I replace it before I took it in and its a doddle of a job - its under the back seat, drivers side.
I'm not sure if its possible this was the problem, but you never know so I thought I'd mention it.

Best of luck. I hated selling mine, it was the best daily driver I've had when it was on song and I still miss it.

JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Tuesday 21st June 2011 quote quote all
I'll mention your thoughts to my specialist though he hates it when i try and self diagnose!

Going to Autobahn tomorrow to be hooked up to the computer to have any fault codes read then we'll go from there.

mini1380cc

960 posts

57 months

[news] 
Tuesday 21st June 2011 quote quote all
JAM,
I had the same symptoms in my z3 (same engine). Try unplugging the Mass Air Flow Meter and take it a drive. If its a faulty MAF, which it well could be it should drive far better but with a little hesitation on pulling away.

If you do try this be sure to mention it to the diagnostics guy as this will through a code which he may take into account.



JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Wednesday 22nd June 2011 quote quote all
Thanks for the reply, I'll mention the MAF to my specialist, car is with him now so hopefully diagnostics will show any issue.

JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Wednesday 22nd June 2011 quote quote all
mini1380cc said:
JAM,
I had the same symptoms in my z3 (same engine). Try unplugging the Mass Air Flow Meter and take it a drive. If its a faulty MAF, which it well could be it should drive far better but with a little hesitation on pulling away.

If you do try this be sure to mention it to the diagnostics guy as this will through a code which he may take into account.
Have disconnected the MAF sensor and on the way back from teh garage the car feels really sluggish so am guessing the MAF was working ok. The specialist thinks its the crank sensor so looks like I'll be having that done. £20 for the part, labour is £320, nice!!

CypherP

4,323 posts

78 months

[news] 
Wednesday 22nd June 2011 quote quote all
I read more and more of people suffering with these problems, and I too used to get this problem on my older E46 325. I had it diagnosed by BMW who confirmed it was OBD code P1638 - Throttle Valve Positioning error - i.e. the sensor that controls the throttle valve wasn't reading correctly, or the throttle valve itself was becoming stuck.

I removed the airbox, air intake pipes and throttle sensor (all of which I was able to find DIY guides for online) and cleaned/replaced the sensor, as well as having a general clean. Since that, I didn't suffer with the same problem. However, it seems that the problem is very difficult to diagnose as it could pertain to a number of causes.

I was also told at the time mine was suffering to check all intake pipes and hoses for minor leaks as a drop in pressure or leaking air/oil may have caused the issue.

Annoyingly, my current facelift 325 coupe has randomly stalled on me a couple of times in the last 6 months and although very infrequent, I'm wondering whether this is indeed a more common fault.

JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Wednesday 22nd June 2011 quote quote all
Annoyingly the plug in diagnostics showed no faults so the specialist is changing the crank sensor as it was at fault on other cars with similar problems. Expensive gamble but hopefully will solve it.

Car never stalls, the revs just drop to barely ticking over and then flooring the accelerator does nothing, until eventually the engine jerks back in to life and its runs sluggishly until the next restart.

TheEnd

14,307 posts

74 months

[news] 
Wednesday 22nd June 2011 quote quote all
Expensive gamble indeed.
If the crank sensor stops working, the engine immediately shuts down.

As far as it is concerned, the engine has stalled/stopped so it doesn't inject any fuel and stops sparking.
The rev counter would also drop a the same time, or if intermittent, it would kick about wildly.

Barreti

5,597 posts

123 months

[news] 
Wednesday 22nd June 2011 quote quote all
JAM35F said:
Annoyingly the plug in diagnostics showed no faults so the specialist is changing the crank sensor as it was at fault on other cars with similar problems. Expensive gamble but hopefully will solve it.

Car never stalls, the revs just drop to barely ticking over and then flooring the accelerator does nothing, until eventually the engine jerks back in to life and its runs sluggishly until the next restart.
Exactly the same symptoms as mine, and changing the crank sensor did nothing.

And if this isn't the problem will the garage stand the cost of the labour or are you paying to extend their expert knowledge rather than benefit from it?

I can't comment on the labour costs per se, though my gut reaction is eek and profanity

Edited by Barreti on Wednesday 22 June 21:26

CypherP

4,323 posts

78 months

[news] 
Thursday 23rd June 2011 quote quote all
Barreti said:
JAM35F said:
Annoyingly the plug in diagnostics showed no faults so the specialist is changing the crank sensor as it was at fault on other cars with similar problems. Expensive gamble but hopefully will solve it.

Car never stalls, the revs just drop to barely ticking over and then flooring the accelerator does nothing, until eventually the engine jerks back in to life and its runs sluggishly until the next restart.
Exactly the same symptoms as mine, and changing the crank sensor did nothing.

And if this isn't the problem will the garage stand the cost of the labour or are you paying to extend their expert knowledge rather than benefit from it?

I can't comment on the labour costs per se, though my gut reaction is eek and profanity

Edited by Barreti on Wednesday 22 June 21:26
I'd have to agree. This won't be the source of the problem, and seeing as a number of people have suggested MAF/Throttle Valve sensor, I'd think it wise to start with these and cover other areas. Plus, with some online guides or a workshop manual, you should be able to get to these yourself.

The revs dropping and sluggish running are both identical symptoms to those that mine suffered with. Its a little odd that a diagnostics check doesn't return any fault codes, as it sounds like the ECU is putting it in 'limp-home' mode, which would almost definitely log a fault. When yours starts to struggle, do you get the Engine Warning/Engine Management light come on?

JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Thursday 23rd June 2011 quote quote all
The MAF has now been disconnected for almost a day. The car is running sluggishly but the drop in revs and lack of power thing didnt happen this morning.

My specialist said if the MAF had gone it would run much better with it disconnected but this isnt the case. It just runs worse, but in a different way than before. Does this indicate the MAF was ok all along?

As for the cost of the crankshaft sensor change, BMW want £390 for it, the specialist £340. so not alot in it but at least the prices I'm getting are all in the same ballpark.

Getting this done is a gamble as both BMW and specialist won't guarantee it will cure problem and if it doesnt its my hard luck, no refund and the search for the fault will continue.

The diagnostic machine not showing anything is really annoying, specialist says this engine often doesnt record all its faults in the memory which makes things difficult for him. I can't really doubt him on this, the computer showed no issue so his hands are tied abit and he has to guess/use his knowledge to diagnose from my description.

Bit torn as to the next move, could be spending £400 and not even curing the problem.

TheEnd

14,307 posts

74 months

[news] 
Thursday 23rd June 2011 quote quote all
£340?

The sensor will be less than £100, £240+ for fitting is a bit much.


Barreti

5,597 posts

123 months

[news] 
Thursday 23rd June 2011 quote quote all
Its worse than that
He already said its £20 for the part and £320 labour eek

JAM35F

Original Poster:

1,004 posts

138 months

[news] 
Friday 24th June 2011 quote quote all
It's 3-4 hours of labour to get to the part hence crazy cost.

Car is at BMW for a second diagnosis today as apparently they build in hidden fault codes for some issues so only main dealer can see them. Hopefully this will show the fault definitively.

caoimhin1

3 posts

37 months

[news] 
Saturday 17th September 2011 quote quote all
Jam,

Did you ever get to the bottom of this? - I have exactly the same problem for a while now and my independant bmw mechanic cant seem to get to the bottom of it. The first poster in the following thread describes the symptoms perfectly!!!

http://www.bmwland.co.uk/forums/viewtopic.php?f=4&...


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