BMW 120D (2005) Idle Issue

BMW 120D (2005) Idle Issue

Author
Discussion

thatdude

Original Poster:

2,654 posts

126 months

Thursday 23rd October 2014
quotequote all
Hi everyone,

A while back I posted a thread regarding a rough idle coupled with a "missfire" on my wifes BMW 120D (2005 model). I;ve since had some diagnostics performed showing the injectors to be fine (smooth running test - 2 injectors were 0.0, one was +0.5 another -0.6 so well within tolerance), but some error codes relating to glow plugs (cleared). The guy also reset the values regarding air and fuel flow, as he stated they need to be reset when the air and fuel filter are changed (I did not know this!). In addition, the engine temp is fine (gets up to the right temp)

The car is still not running well; cruising at low engine speeds (town driving) gives rise to no major issues, but a run at motorway speeds and then back down to idle gives rise to the idle "hunting" and what is best described as a missfire.

It has been suggested this may be related to the swirl flaps. I'm not very clued up on these parts; could they give rise to rough idle? What other parts should be considered?

I am at least aware of the dangers of a swirl flap finding it's way into the engine. I'd quite like to avoid that.

Any input is welcome,

Thanks

this dude

thatdude

Original Poster:

2,654 posts

126 months

Friday 24th October 2014
quotequote all
Follow up:

I'm going to keep this updated incase anyone else should ever have a similar set of symptoms.

The car ended up running worse after everyting was reset, which suggests either:

  • something got worse as a result of reseting everything
or

  • the thing that is wrong was being masked by the engine managment, which "learns" a little bit and adjusts everything accordingly to work towards a smooth running engine
At the moment, I am running with the second theory. The mechanic has taken the car away, and will have the inlet manifold off to inspect the swirl flaps and see if they are indeed the issue, as per his hypothesis.

Either way, it will be an expensive fix (but still cheaper than a new car). My wife is considering changing the car (once fixed) after the winter anyway since she dosnt do many miles any more

thatdude

Original Poster:

2,654 posts

126 months

Monday 27th October 2014
quotequote all
Follow up 2:

The guy took the inlet manifold off; everything is caked up with gunge. The swirl-flaps are ok except for the fact they are not closing fully due to said gunge. The inlet ports on the head are quite coked up, strangling the engine of air. I suspect the engine management dosnt know how best to fuel the engine, hence the problems.

Looking to get everything cleaned up. head off, check valves, clean out the inlet manifold and swirl flaps.

Missus got very grumpy last night when talking about replacing the car.

anonymous-user

53 months

Monday 27th October 2014
quotequote all
outside shot: Check the engine mounts!

My 330d sheared an engine mount, and the effect was to make the engine sound like it had a misfire in the cabin and with the bonnet up at idle

Sardonicus

18,928 posts

220 months

Monday 27th October 2014
quotequote all
thatdude said:
Follow up 2:

The guy took the inlet manifold off; everything is caked up with gunge. The swirl-flaps are ok except for the fact they are not closing fully due to said gunge. The inlet ports on the head are quite coked up, strangling the engine of air. I suspect the engine management dosnt know how best to fuel the engine, hence the problems.

Looking to get everything cleaned up. head off, check valves, clean out the inlet manifold and swirl flaps.

Missus got very grumpy last night when talking about replacing the car.
Good old EGR induced gunk you cant beat it irked hope you get it all sorted.

thatdude

Original Poster:

2,654 posts

126 months

Tuesday 28th October 2014
quotequote all
Max_Torque said:
outside shot: Check the engine mounts!

My 330d sheared an engine mount, and the effect was to make the engine sound like it had a misfire in the cabin and with the bonnet up at idle
Ah, good call! With the way it's been running I should think a cautionary check of the mounts would be a good idea anyway.


Sardonicus said:
ood old EGR induced gunk you cant beat it irked hope you get it all sorted.
haha! I would like to blank the EGR off but I'm worried about toher problems. The EGR itself lookd not too bad, I suppose the EGR is hot enough to have everything flow through, and then as it goes down the (cooler) inlet manifold everything "precipitates" out. Evidence for this is towards the rear of the engine is worse...

Will post some more updates as and when. If I can get a few pictures I'll upload them too


thatdude

Original Poster:

2,654 posts

126 months

Thursday 30th October 2014
quotequote all
Follow up 3:

Word from my father-in-law who spoke with the mechanic last night is he has the head off, and has found everything to be ok now he can see it all properly. He's going to clean it up without dismantling too much (certainly no valves to be taken out). So that's good news.

I'll have a chat with him later and see what the full situation is and update this post.





thatdude

Original Poster:

2,654 posts

126 months

Monday 3rd November 2014
quotequote all
Follow up 4:

I got in touch with the mechanic looking after the car, and it tuns out he didn't take the head off. Upon removing the valve cover, he had more light to inspect the valves, and using a boroscope could see that everything was in pretty good condition for a 75,000 mile / 9 year old engine. He cleaned up what he could (have a given set of valves closed, soak in a solvent and then clean off with a rag on a screwdriver, turn the crank, do the next set) but importantly the inlet manifold was left to soak in parraffin / kerosene, de-gunking everything. This took a bit of time but it has come up really clean, allowing the swirl flaps to operate smoothly and, importantly, all of them close correctly. None of them were loose or worn. He put everything back together with new gaskets, and also put in a new air filter and some new breather filters (or something like that). He took it for a good test run, and found the idle to be good and smooth, and there to be more power across the rev range.

The car is now back with my wife, who has driven it to work this morning; she wasnt doing her usual commut though, so it's unlikely the swirl flaps will be fully opened for a significant length of time like they are at motorway speeds (as is my understandning) so we may not really know how things are until a few runs. She says it is running better though, and when we got the car back last night I had a careful listen to the ildle in both Drive and Park (neutral) and it is sounding smoother - no hunting, no missing.

I shall keep the thread further updated, but so far here are some key points:

  • initial symptoms: rough idle, coupled with a "missfire" / engine rocking. Running smooth though under even a light load
  • some lack of power
  • initial tests looked at injector values (Smooth Running Test) - injectors were well within acceptable tolerances (tolerance is +/-2.5 units, two had values recorded as 0.0, one had -0.6 and another had +0.5). Also reset were the calibration for airflow and fuel flow (this needs to be done every time the air and fuel filters are changed, the vehicle learns as they get blocked (but may not be able to go the other way..?). Upon reseting these values the engine ran worse.
  • engine temps fine - no thermostat issues
  • vehicle taken back by mechanic, who inspected the inlet manifold - a large buildup of gunk and particulates in the manifold, and on the swirl flaps. valve head also looked dirty, but on closer inspection (valve cover off) not so bad.
  • everything cleaned up and put back in place, new air filter. Engine now running much better at idle
So if you have a poor running E87 120D (or 320D or 520D etc etc etc) and the injectors and temps are fine, then it may be gunked up swirl flaps (or poorly working swirl flaps).


packman10_4

245 posts

193 months

Friday 7th November 2014
quotequote all

If it is the N47 engine id be inclined to get the timing chain checked out ... as this is a common problem on all BMW,s with the N47 engine from 2005 to 2009 I think .. its the tensioner that fails and when it is on its way out the chain is slack for a few secs and the idle goes all over the place ... google the problem just make sure u have a big brew at your side ....

thatdude

Original Poster:

2,654 posts

126 months

Friday 7th November 2014
quotequote all
It's not the N47 engine - I understand it has the M47TU2D20 engine. No cam chain issues to report with this engine, and it's idling real nice now (and running better too!)

thomsonfrase

1 posts

94 months

Monday 23rd May 2016
quotequote all
thatdude said:
Follow up 4:

I got in touch with the mechanic looking after the car, and it tuns out he didn't take the head off. Upon removing the valve cover, he had more light to inspect the valves, and using a boroscope could see that everything was in pretty good condition for a 75,000 mile / 9 year old engine. He cleaned up what he could (have a given set of valves closed, soak in a solvent and then clean off with a rag on a screwdriver, turn the crank, do the next set) but importantly the inlet manifold was left to soak in parraffin / kerosene, de-gunking everything. This took a bit of time but it has come up really clean, allowing the swirl flaps to operate smoothly and, importantly, all of them close correctly. None of them were loose or worn. He put everything back together with new gaskets, and also put in a new air filter and some new breather filters (or something like that). He took it for a good test run, and found the idle to be good and smooth, and there to be more power across the rev range.

The car is now back with my wife, who has driven it to work this morning; she wasnt doing her usual commut though, so it's unlikely the swirl flaps will be fully opened for a significant length of time like they are at motorway speeds (as is my understandning) so we may not really know how things are until a few runs. She says it is running better though, and when we got the car back last night I had a careful listen to the ildle in both Drive and Park (neutral) and it is sounding smoother - no hunting, no missing.

I shall keep the thread further updated, but so far here are some key points:

  • initial symptoms: rough idle, coupled with a "missfire" / engine rocking. Running smooth though under even a light load
  • some lack of power
  • initial tests looked at injector values (Smooth Running Test) - injectors were well within acceptable tolerances (tolerance is +/-2.5 units, two had values recorded as 0.0, one had -0.6 and another had +0.5). Also reset were the calibration for airflow and fuel flow (this needs to be done every time the air and fuel filters are changed, the vehicle learns as they get blocked (but may not be able to go the other way..?). Upon reseting these values the engine ran worse.
  • engine temps fine - no thermostat issues
  • vehicle taken back by mechanic, who inspected the inlet manifold - a large buildup of gunk and particulates in the manifold, and on the swirl flaps. valve head also looked dirty, but on closer inspection (valve cover off) not so bad.
  • everything cleaned up and put back in place, new air filter. Engine now running much better at idle
So if you have a poor running E87 120D (or 320D or 520D etc etc etc) and the injectors and temps are fine, then it may be gunked up swirl flaps (or poorly working swirl flaps).

Hi mate,

Sorry to dig this up from the graveyard!
Have had the same issue as you described for a while with my 2006 120d now.
Leak off test was done and injectors seemed to be fine.
I have advised garage of the details in this thread but just wanted to ask:
After the inlet manifold etc was cleaned up did the issue go away?
Did you get any error codes when experiencing this issue? I've got a 4B10 smooth running control error code being thrown up but from the plethora of forum posts I've read, yours is the closest match..