Cold Start Misfire Problem [Worse in Cold Weather]

Evening all,

I am a member on bimmerforums also and was just looking for a larger variety of opinions.

Scenario

E46 320Ci M54 - Starting from cold

Can feel car vibrating (misfiring) at initial idle of 1k, and this normally goes away once the idle drops down to 700rpm.

If the misfire does not go away then turning off and restarting cures this.

Fault Code

Misfire Cylinder 5. Although does produce the occasional Cylinder 2.

Diagnostics so far

Spark plugs renewed
Ignition coils swapped
Fuel injectors swapped
Rocker cover gasket replaced
Block tester completed (all ok)
Compression test completed (good results)
ICV cleaned
DISA cleaned
Intake hoses checked for leaks (all ok)

Indy thinks it is either

Hydraulic valve lifter problem, although I am not sure how this ties in with the compression test being fine.

Or

A problem with the control signal from the ECU to either coil or injector for cylinder 5.

Using INPA the smooth running for cylinder 5 goes off the scale.

Any input is most welcome as I don't want to keep forking out money for nothing.

Vanos seals are bad

Why would that only affect cylinder 5?

ok, after some re-reading and research,


are you hearing any noises coming from the engine bay?
is it still throwing codes after you fixed all of those items?
i'd do a smoke test to completely rule out a vacuum leak

The indy reports a very quiet ticking from the top end. (Although some say this is normal)

Yes the codes are still being sporadically thrown.

And a vacuum leak would cause issues with all cylinders.

Originally Posted by hontoir

And a vacuum leak would cause issues with all cylinders.

not necessarily, I still suggest doing a smoke test to completely rule out a leak as the cause of the issue. visually inspecting is ok, but these things are easy to miss and the smoke test may say you a lot of time and headache.

If there were a vacuum leak, would this not cause problems both cold and hot? As this is only on a cold engine, and it gets worse when the weather is colder.

Originally Posted by hontoir

If there were a vacuum leak, would this not cause problems both cold and hot? As this is only on a cold engine, and it gets worse when the weather is colder.

cold weather might have actually caused the vacuum leak. parts become cold and brittle and then eventually crack.

most issues that deal with rough idle and cold weather tend to point to the vanos though

Is there anyway of testing the vanos?

Originally Posted by hontoir

Is there anyway of testing the vanos?

not that I'm aware of. It's just one of those parts that you look in to when you get certain symptoms. I haven't rebuilt mine yet but from reading up on it and looking at the DIY's it doesn't seem that bad. All you do is just take it apart and replace the rubber seals (more or less). Do some research, there's a bunch of VANOS rebuild threads out there.

I would imagine that the oil separator is original, car has only done 54k. However, I do not want to fork out big money on items that MAY not be the cause.

I have already had it out to clean it, it is fitted with the OEM orange seal which looked to be in good condition.

Also, how would I go about checking the operation of the oil separator (CCV)?

so did you fix the problem? if yes what was the problem?

It is going in to have the lifters changed on cylinder 5 next weds.

this sounds like the exact same problem im having.

Trust me on this, I see all kinds of tail chasing and big expenses on lot of parts replacements. Skip the VANOS for now, my be an issue, BUT, please read my original post and do the following before you go down the VANOS road.

1. Replace the DISA O-ring with the ebay $12 part. You want a silicon based part, but rubber will work for a while, but the silicon is more flexible. The DISA O-ring is a major problem due to the the size of the opening and the original silicon getting hard and not expanding and contracting causing cold vacuum leaks. The DISA should not pull out easily when you go to remove it, it should require a good pull to remove, otherwise the O-ring is bad. The DISA usually caused more misfires in the center cylinders from what I have seen.

2. Replace the lower CCV oil drain back to the dipstick tube. This is either cracked or oil soaked and close to breaking or cracking.

I would not spend any more money on other items until at least these 2 items are REPLACED, not just inspected.

Again, this may not solve your problem, but 2 items are VERY common and often overlooked.

http://forum.e46fanatics.com/showthr...616&highlight=

Let us know how you go with the lifters. I have read countless threads on the issue and everyone has their opinions but there is never any conclusion to advise the real issue.

I have been advised that the lifters are a common cause too.

Good Luck

I am having a smoke test done prior to having the lifters changed. This will identify any issues with the intake including the DISA seal.

DISA may not be picked up in a smoke test, partly a function of temperature as the DISA contracts and expands quite a bit.

How would the DISA cause a misfire on ONLY ONE cylinder?