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E46 318i F/L Rough Idle Problem and more
09-12-2011, 08:16 PM (This post was last modified: 09-12-2011 08:21 PM by Syl.)
Post: #1
E46 318i F/L Rough Idle Problem and more
Hey guys

I need some serious help concerning my car's idle and starting. I've been there, I've tried that, it got better, it got worse etc. etc. I'm out of ideas so now I'm here!!

It's a 2001 E46 318i Facelift Automatic. (N42 2L engine)
Around 200k on the clock.

Heres the story:

The car has had a slight rough idle since I got it beginning of the year,  but I didnt really worry about it 'cause it was driving fine. Then a few months ago the car started to misfire badly and was incredibly rough when idling and even worse on pull-away. The engine shook so badly oil splattered out from the oil cap, spilling onto the manifold and making some lovely smoke signals from under the bonnet scaring myself s***less.  But no worries, I figured it was the sparkplugs, so I replaced them, saw that the old ones were completely toasted, and the car was fine after that. Nice and smooth again, but still slightly rough idling when standing still at robots etc. and sometimes had a bit of trouble starting, meaning I had to pump the gas for a few seconds for the revs to climb and have it warm up a bit before I could let go and have it idle on its own.

Then a couple of months ago, I was going through a long dip, and just as I pumped the gas to accelerate up the hill the car just died! Gearbox light came on together with ASC light, and the car wouldnt even drive above 20km/h before just cutting out again. So I thought maybe it's the alternator or battery, checked the alternator and it was fine, Charging the battery at 14volts.  I knew the battery was not well as I had to jumpstart my car a couple of times after just listening to radio while the car was off before. So maybe one of it's cells just died I thought. So I went and got a brand new one, fitted it, and... the car still cut out.
As that was the end of my wisdom I decided to swallow my pride and take the car to a BMW repair shop close by (Not official dealer), and he connected it to his computer and got some error codes for the cam and crank sensors. After scaring myself s***less again after hearing how much he wants to charge me to replace them, I took the car to BMW dealership for a second opinion, and got the same news from them. But they were actually cheaper than the other private BMW repair guy!! Imagine that!!
Anyways, they replaced the sensors as well as the oil seperator pipe and a rubber boot thats part of the air intake system.
Cool! The car is running again.  Untill a few weeks ago when it decided to stutter, sputter and die as I was standing still whilst idling. When i turned the key the engine would turn, but just wouldnt ignite. So i thought it might have overheated (even though the temp gauge showed normal) as I did just have a long journey and sat in traffic a bit. So I left it overnight and the next day it was fine again. Still rough idle though, and stil having difficulty starting.
So I did some research and read of cars with more or less the same symptoms and got it fixed by replacing the fuel filter. I also got some fuel and injector cleaner which actually helped the car run a bit smoother, it was more stable. So a few days ago went and got a new fuel filter from BMW and went off home to go and fit it, only to have the car die on me again with a stutter and a splutter. This time i could start the car again but only to have it die again slowly as soon as I pumped the gas a bit. But anyway, towed the car home, replaced the filter and it was lekker! Running better than it ever did since I got it.
But it still basically has the same symptoms. Rough idle (even more unstable after a long day's drive), difficulty starting (it only starts after about  2 tries and I have to keep the revs above 2000 until it warms up and something kicks in).


Short version:
-Rough idle.
-Trouble starting.
-Replaced sparkplugs, checked coils.
-Car dies when i accelerate
-Replace battery
-Replace cam and crank sensors. + oil seperator pipe and rubber air intake boot.
-Car drives fine. Then dies with different symptoms, still rough idle and starting problem.
-Replace fuel filter.
-Car runs better, but still unstable, rough idle, trouble starting.

So, any ideas anyone??  I really am not looking forward to taking it to the dealership again. And I fear it might die on me again soon. Please guys!!!

Thanks in advance!
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10-12-2011, 08:13 AM
Post: #2
RE: E46 318i F/L Rough Idle Problem and more
Howzit man. Sorry about your troubles.

It could be your Maf, Coils, O2 sensor and most likely fuel pump.

However I do believe the VVT stepper motor has alot to do with this.

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10-12-2011, 10:08 AM
Post: #3
RE: E46 318i F/L Rough Idle Problem and more
Hey Trigger
Thanks for replying.

I just went and unplugged the MAF sensor, started the car, and checked if the idle changed or anything. Plugged it back in, started the car and checked again. I did this a few times but it seems to stay more or less the same except for the transmission light that comes on when the MAF is unplugged.
It's still a bit rough, and every now and then it drops a bit, and quickly stabilizes itself.

And yesterday while the car was idling I unplugged the sparkplug coils 1 by 1, and they all seemed to be working as the car started stuttering after unplugging each one.

So I guess that rules out the MAF and coils, and leaves the more expensive stuff.

Where is the fuel pump and O2 sensor located?
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12-12-2011, 07:42 PM
Post: #4
RE: E46 318i F/L Rough Idle Problem and more
Okay guys, I've got a theory.

I've noticed when the car has trouble starting, it's as if it is not getting enough fuel, and then just dies again. After about 2 or 3 tries it almost just starts instantly. And when driving, it drives beautifully! Smooth, no problems at all, idle not too bad.
Then when I switch of the car, lets say for just an hour, it has exactly the same problem starting again.

So, what I'm thinking is that since the fuel system uses a vacuum, that there might be a leak somewhere. So, when the car has been off for a while, it slowly loses its vacuum because nothing is pumping any more, then when you try and start the car it first has to build up that vacuum again to get going again, and then as long as the car stays on, it holds the vacuum, and has no problems.

What do you guys think? Solid theory? Any ideas where I can start looking for a leak? Maybe the hoses arent tied proparly, or maybe the fuel pump is not well?
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16-12-2011, 10:20 PM
Post: #5
RE: E46 318i F/L Rough Idle Problem and more
Hey guys
Time for an update.
I did an engine flush and changed the oil and oil filter today, and its a good thing 'cause the oil filter was completely worn out. It was not a pretty sight!

So know the symptoms have changed. I'm not worried about the idle anymore, once the car is running it is really smooth now, and it drives really smooth too. But, it is still not consistent when starting. It starts without me having to step on the gas or anything, idles for about 3 seconds, then just dies. After the second try or so it seems fine.
Also when it dies it sometimes starts making this click-click-click..... noise until I physically remove the key from the ignition. And then when I start the car again its fine.
Any idea what this clicking is? I'm feeling the only left that could be faulty is the VVT. Does this sound like a characteristic of a failing VVT? Any way I can service it? Where is it situated?
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16-12-2011, 10:40 PM
Post: #6
RE: E46 318i F/L Rough Idle Problem and more
Hey bud no idea , you should put it on a diagnostic system though . Should pin point your problem out . And don't know why the other members aren't helping out here .

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17-12-2011, 10:27 AM
Post: #7
RE: E46 318i F/L Rough Idle Problem and more
Where is LZ?

He should have all the answers..
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17-12-2011, 12:34 PM
Post: #8
RE: E46 318i F/L Rough Idle Problem and more
(16-12-2011 10:40 PM)Karthik Wrote:  Hey bud no idea , you should put it on a diagnostic system though . Should pin point your problem out . And don't know why the other members aren't helping out here .


I guess I'm gonna have to take it someplace. Because i am really stumped! Cant think of what else to try. The thing us the only place I know of is gonna charge R380 for that. And BMW is even more!
I was hoping to get some answers here but the forum seems really quiet...
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17-12-2011, 06:43 PM (This post was last modified: 17-12-2011 06:48 PM by Syl.)
Post: #9
RE: E46 318i F/L Rough Idle Problem and more
So, I just went and started the car again to see if anythings changed, but it's still the same.
1st try - splutters up to 750rpm and died.
2nd try - it was much smoother, went up to about 1000rpm and then died. Then that new click sound started. I checked under the hood and it seemed to be coming from the throttlebody. It continued on clicking for about 15 seconds after the car was off.
3d try - stepped on the gas a bit until it reached about 1500rpm, left my foot at exactly the same position and the revs slowly climbed to about 2500rpm on its own, let go and it was fine idling at 750rpm.
Then the car started revving itself!! It jumped up and down constantly between 1200 and 1800 rpm, unless I put it in drive then it was stable at about 900rpm, but as soon as i put it in neutral it started revving again. I took a video of it! It was freakin wierd. Anyway, I searched the web quickly and some guys mentioned that the oil cap is not correctly fastened. I checked and indeed it was not fastened correctly. So i just fastened it and the car seems to be fine now.


I looked around a bit and i saw Zaleonard@DentDoctor mentioned that You can test the vvt motor.
http://www.bmwfanatics.co.za/showthread.php?tid=18650
Can someone pleas advise where it is located and how I can get it out to test it??
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18-12-2011, 10:59 AM
Post: #10
RE: E46 318i F/L Rough Idle Problem and more
haha Okay I spoke too soon.
This morning when I started the car again, it stuttered but took as I stepped on the gas a bit, and I drove for a few minutes and when I parked again and put the car in Park, it started doing that revving thing again.
Also, my EML light is now on! Ideas?? PLease... Anyone...

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18-12-2011, 01:26 PM
Post: #11
RE: E46 318i F/L Rough Idle Problem and more
I just Google'd for a pic of the vvt motor and saw where it was located. In between the sparkplug coils under the tappet cover if anyone was wondering..

Anyway, I measured it and there seems to 0.5ohm between the positive and negative poles when measured on the shell of the unit. So I gues that means that the VVT motor has gone.

I'm gonna phone a guy to get a quote tommorow, lets hope it's not too much.
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18-12-2011, 05:32 PM (This post was last modified: 18-12-2011 09:15 PM by zaleonardz.)
Post: #12
RE: E46 318i F/L Rough Idle Problem and more
Bud,

Sorry I have been out the last few days.

I too have had N42 issues like you cannot believe.

I was going to point at the VVT motor first off, because usually thats the trouble.

If you are getting a resistance value on the VVT motor, then the motor did go poof.

Replacing the VVT motor is really easy, but you have to calibrate it again using DIS if you change it, so I would not DIY this one, unless you have DIS laying around.

What you can do for a test, on the manifold, in the front, you will find the VVT sensor, if you unlplug this, the valves should open to maximum.

However, If you have an EML light, this is a deeper indication of a problem, as most of the VVT system does not cause EML errors, due to a stupid design by BMW.

If you are close to the boksburg area, come and see me, I will sort this out for you.

I will be on the other side if anybody needs me Bluebiggrin
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18-12-2011, 09:12 PM
Post: #13
RE: E46 318i F/L Rough Idle Problem and more
Ah thanks for replying ZL!!

I am gonna try and test that vvt sensor tommorow evening!
I'm not too sure where it is though. On the front there is a sensor you mentioned.
Is it like the one in this pic?
http://img374.imageshack.us/img374/6925/002dr9.jpg
I found this via google.

The EML light seems to have gone now. I think it might just have had something to do with the oil and oil filter I changed on friday. But I will keep a lookout for it.

Wow thanks. I might just take you up on your offer! I'm getting really frustrated now! I will let you know!
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18-12-2011, 09:29 PM
Post: #14
RE: E46 318i F/L Rough Idle Problem and more
Sh!t Syl I really hope you and LZ gets this sorted.

I still can't believe how quiet this thread has been. Maybe all on holiday I don't know.

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18-12-2011, 09:53 PM
Post: #15
RE: E46 318i F/L Rough Idle Problem and more
(18-12-2011 09:29 PM)Henry330i Wrote:  Sh!t Syl I really hope you and LZ gets this sorted.

I still can't believe how quiet this thread has been. Maybe all on holiday I don't know.

Haha thanks man!! Me too!

I suspected the same thing hey! I guess I just have bad timing. (yes I see the pun thank you! ;-) )
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18-12-2011, 09:58 PM
Post: #16
RE: E46 318i F/L Rough Idle Problem and more
Yep,

December fanatics are quiet.

The sensor sits on the head just in front of the intake manifold.

It is Right on top, and has an electric cable that has probably about 10 or 16 pins going to it, connector is the size of your thumb nail and its an L-Shaped thingy.

wish I had a picture, but ya cant really miss it if you take off the plastic covers.

I will be on the other side if anybody needs me Bluebiggrin
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18-12-2011, 10:41 PM (This post was last modified: 18-12-2011 10:43 PM by zaleonardz.)
Post: #17
RE: E46 318i F/L Rough Idle Problem and more
[Image: 326.png]

Part No 7

But the base of the sensor is physically in the head, with only the connector sticking out, i think its between cyl 1 and 2 intake manifold air tube.

I will be on the other side if anybody needs me Bluebiggrin
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19-12-2011, 06:50 PM (This post was last modified: 19-12-2011 07:53 PM by Syl.)
Post: #18
RE: E46 318i F/L Rough Idle Problem and more
Thanks ZL! I just took a quick look, and I see 3 plugs.
Heres a photo I took with the 3 plugs hi-lighted.
http://img38.imageshack.us/i/imageqqgg.jpg/

Left, top or right??

Thanks man! I really appreciate your help!!


EDIT: Nevermind!! I was looking in the wrong place. I found it! I think. Next to the coils close to the vvt motor. The plug is rounded.
Okay I just started the car with the sensor unplugged, and it seems okay. But tge car is warmed up now so then it is fine most of the time.
So I'm gonna try again in an hour or so and will see wht it does.

Is it safe to drive the car with that sensor unplugged? What does it do?
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19-12-2011, 09:41 PM
Post: #19
RE: E46 318i F/L Rough Idle Problem and more
Well, tried the car again. 1st try; spluttered up to about 500rpm, dropped to about 200rpm, died...
2nd try; started fine without any effort, stabelized on 750rpm, got smoother, died after about 2min idling...

So short story short, either I disconnected the wrong sensor, or the problem is worse than the vvt motor? Please tell me I disconnected the wrong sensor!!
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19-12-2011, 10:17 PM
Post: #20
RE: E46 318i F/L Rough Idle Problem and more
Well,

Its hard to tell, but you cannot ignore the fact that you are picking up a resistance value between the body and the coils, which means VVT motor.

In theory, the valves should open fully with the VVT position sensor disabled. It could be that the VANOS is screwing around and expecting the VVT to do something which it wont if it returned to the WO position.

Bud,

Grab a VVT motor from BMW, bring me this car, I will fit it for you quickly (its about an hour to 2 job) and we take it from there.

Notice however, that even when you unplug the VVT motor/sensor, that you still dont get a EML light, which just goes to show how poorly the VVT is integrated.

In fact, the N42 and the N46 is bolt for bolt the same, except for upgraded electronics on the N46.....


I will be on the other side if anybody needs me Bluebiggrin
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