Misfire and rough idle, e46

[Erinra]

So I haven't driven my e46 330 all winter (although unfortunately my new garage isn't finished yet so it had to sit outside) and just fired it up and to my dispair it wasn't running as smoothly as it did last time.. The idle was rough going up and down so I read the diagnostic codes which said misfire cylinder 3, 4, 5 and also Fuel Control mixture.

So I just ordered some new sparkplugs (NGK) but what else should I check?

Thanks in advance,

[GuidoK]

Also check the rubber intake boots for tears.
Especially the lower one.
There are I believe also some rubber caps that cap off some extra inlets for vacuum hoses at the back of the manifold that tend to disintergrate.
This indeed looks like a vacuum leak somewhere.

[ShocknAwe]

Misfire? Plugs coils injectors first.

[GuidoK]

I think someting with plugs/coils/injectors would throw a more specific code to 1 cylinder.

[TriumphTim]

All of the above sounds good but I would clear the codes and run some fresh gas with injector cleaner or water remover first.

[Erinra]

Originally Posted by Jturbo_M3

You should probably check the vacuum lines for any cracks, or leaks as that can cause misfires.

Originally Posted by GuidoK

Also check the rubber intake boots for tears.
Especially the lower one.
There are I believe also some rubber caps that cap off some extra inlets for vacuum hoses at the back of the manifold that tend to disintergrate.
This indeed looks like a vacuum leak somewhere.

Thanks for the replies, I've just got ahold of a new CCV set which I will replace tomorrow (11617533400, 11617533398, 11617533399, 11157532629, 11617504536).
Also the rubber boot (13541438761) and the tube elbow (13541438759).

Originally Posted by ShocknAwe

Misfire? Plugs coils injectors first.

Originally Posted by GuidoK

I think someting with plugs/coils/injectors would throw a more specific code to 1 cylinder.

I replaced the sparkplugs and I'll post some pictures later, I think the coils looked fine, but maybe a defective coil isnt visable to the naked eye?

(I tried starting the engine after replacing the sparkplugs but It was to no avail but I guess they needed replacing anyway since I don't know the last time they we're replaced)

Originally Posted by TriumphTim

All of the above sounds good but I would clear the codes and run some fresh gas with injector cleaner or water remover first.

Oh yeah, Thanks for this tip, I'll get some fuel additive to, it wont harm.

I'm also going to clean the MAF since I'm removing the boots anyway.

I cleaned the codes with a simple ELM327 and phone app, maybe I'll have to plug in my BMW 1.4 scanner and my laptop..


Anything else I missed so far?

[GuidoK]

Originally Posted by Erinra

Anything else I missed so far?

You can locate vacuum leaks by spraying some brake cleaner localized on rubber parts. Where there is a leak, the brake cleaner is sucked inside and burned, raising the RPM slightly.
Obviously be careful with this method and don't do this with a hot engine and hot exaust and spray in the direction of the hot exhaust as brake cleaner is obviously very flammable....

Another way is by injecting smoke into the inlet system by a specialized smoke machine (inlet has to be capped off).
Where the smoke comes out, there is your leak. However this requires that special smoke machine, which is a fairly expensive tool.

The rubber blind caps on the inlet manifold that can perish I was talking about are #15 and #17 in the link below
http://bmwfans.info/parts-catalog/E4...nifold_system/

The O ring of the air inlet temperature sensor can potentially also leak, however this is less common. I think the lower intake boot is the usual culprit. A tear there causes a significant size of a leak

[Our03z4]

Originally Posted by Erinra

Thanks for the replies, I've just got ahold of a new CCV set which I will replace tomorrow (11617533400, 11617533398, 11617533399, 11157532629, 11617504536).
Also the rubber boot (13541438761) and the tube elbow (13541438759).







I replaced the sparkplugs and I'll post some pictures later, I think the coils looked fine, but maybe a defective coil isnt visable to the naked eye?

(I tried starting the engine after replacing the sparkplugs but It was to no avail but I guess they needed replacing anyway since I don't know the last time they we're replaced)



Oh yeah, Thanks for this tip, I'll get some fuel additive to, it wont harm.

I'm also going to clean the MAF since I'm removing the boots anyway.

I cleaned the codes with a simple ELM327 and phone app, maybe I'll have to plug in my BMW 1.4 scanner and my laptop..


Anything else I missed so far?

Like I always tell people, the MAF sensor connector wires break on these engines. You can buy a kit to replace the connector quite easily. All my random codes I chased for years have vanished after replacing it. Car no longer hunts for idle at start up. Just a thought for you if you can't trace the issue down.

[GuidoK]

If the maf sensor wires are broken, that would be really easy to diagnose.
Just read out the amount of airflow and see if that's a plausible value. Unplugging and plugging in the MAF would make no difference in this readout.
For me, this is the first time I hear of this being an issue on the m54.

[Chihuahua]

Originally Posted by Erinra

looked fine, but maybe a defective coil isnt visable to the naked eye?

No they're usually not, and they are a common failure point for M52/M54 engines. I used to swap a coil from a known good cylinder to troubleshoot and confirm a bad coil.

[Our03z4]

Originally Posted by GuidoK

If the maf sensor wires are broken, that would be really easy to diagnose.
Just read out the amount of airflow and see if that's a plausible value. Unplugging and plugging in the MAF would make no difference in this readout.
For me, this is the first time I hear of this being an issue on the m54.

Mine weren't fully broken, they become loose in the pins and lose contact intermittently. Made it much harder to track down and drove me nuts for the longest while.

[Erinra]

Originally Posted by GuidoK

You can locate vacuum leaks by spraying some brake cleaner localized on rubber parts. Where there is a leak, the brake cleaner is sucked inside and burned, raising the RPM slightly.
Obviously be careful with this method and don't do this with a hot engine and hot exaust and spray in the direction of the hot exhaust as brake cleaner is obviously very flammable....

Another way is by injecting smoke into the inlet system by a specialized smoke machine (inlet has to be capped off).
Where the smoke comes out, there is your leak. However this requires that special smoke machine, which is a fairly expensive tool.

The rubber blind caps on the inlet manifold that can perish I was talking about are #15 and #17 in the link below
http://bmwfans.info/parts-catalog/E4...nifold_system/

The O ring of the air inlet temperature sensor can potentially also leak, however this is less common. I think the lower intake boot is the usual culprit. A tear there causes a significant size of a leak

Update:
I've now changed the CCV parts and also the two parts on the intake boot (yes they both had tears). I also cleaned the MAF with CRC MAF cleaner. Changed Oil, Oilfilter, Airfilter, (Already changed the sparkplugs) and also added some fuel additive to remove any water in the gas.

The car now starts and runs but I can tell its not running smooth on idle, I cleaned the engine codes and the ones I get now are the following:

P0171, P0174, P1083, P1347 and P0056..

I'm guessing I've got a leak somewhere else. I've yet to check #15 and #17 on the inlet manifold.
The oring on the dipstick tube was toast so I've got the get a new one for that. I'll get one for the intake sensor to, might just as well buy a kit of orings.

Also I found this cable behind the DISA that was not connected to anything and I could not find where to connect it? Does anyone know what it is and where it should go? (Pics comming soon)

[Erinra]

The cable I mentioned.

[Our03z4]

Originally Posted by Erinra

The cable I mentioned.

If I remember right that is a diag port on the M54. Did it look like it had been plugged in or is it dirty inside?

[GuidoK]

Looks to me either the disa connector or the fuel tank breather valve connector.
Those are both 2 pin. (If I'm not mistaken, I see the connector on your disa not having a plug in it....or does that lay somewhere else?)
Normally the plug for the disa (and some other plugs) look a bit different as they have a cap on top of it, but with this plug it looks like some plastic parts broke off?

Idle control valve also sits there but I think that's 3 pin.
I believe there's also an electric valve between the air pump and inlet manifold. That might also be a 2 pin connector.
And there's a temperature sensor in the inlet manifold, also 2 pin in that shape, but the cable looks a bit short for that.
And the crank sensor also sits there, but I think that's a different shape connector (but also 2 pin I believe).

And it's difficult to see how long that wire is, but if it can route the other way, it could also be the oil pressure sensor or intake vanos relais.

So take your pick...

I put an arrow at your disa connector that misses it's plug....


I don't know if that'll solve all your codes though....

[Erinra]

To me everything seems to be plugged in, Idle control valve, DISA, EVAP, throttle body. I'll get a better picture later.

It's definitely not that long, it had no room to fit any other connector. From the small clip it had only a couple of inches the most I think.

[Steeler]

Originally Posted by Erinra

The cable I mentioned.

I believe that connector is for the ICV.

[GuidoK]

There's also a water temp sensor low at the back of the cylinder head

[Erinra]

Long time reply.

I'm still confused about the unplugged cable, it's not the ICV nor the DISA, as you can see on the attached pictures it's a different connector..

Also when looking behind the intake i found this withered vacuum hose? Or what is this and where does it go to?

Thanks in advance