Cold start misfire

[bastereo]

For the last few months my 2001 3.0 has had a slowly worsening cold start misfire.

When I began it was just a couple individual misses after sitting overnight. It has progressed to the point where, after sitting for an hour, now it misses for 30 seconds and the computer catches it and shuts down the number one cylinder. So I have to restart the car. Then its good to go and runs great.

It sets a code for misfire cylinder #1 and occasionally another cylinder at random, but usual just # 1

I have checked different things over the past months:
Plugs were new (less than 5000 miles) so I moved them around multiple times. All appeared the same, none stood out.
I swapped the coil packs around multiple times, trying the coil from cylinder 3, 4 and 6
I had another set of coils laying around, installed them
Performed a leak down test, less than 15% leakage on cylinder number one.
I swapped out an entire new set of fuel injectors.

There is a technical service bulletin out for our cars for the lifters, one of the conditions listed is for sticking lifters causing a cold start misfire.
Replaced the entire set of lifters.

All that and no change, actually continued to worsen.

Starting back from square one, tried a known good maf, no change.
Tried a new plug, no change
Smoked the intake for leaks, let a BMW tech friend look at it, no leaks


I know none of you will believe me, but I finally figured it out and looking at few details I skipped over, its logical.

It does smoke some in the morning, I had just assumed it was condensation in the exhaust, until I was accelerating out of my driveway and saw the volume of smoke, the next morning I smelled it, and it stunk bad!
I did add a couple cups of coolant during this time period, but my x-rings on the transmission cooler were seeping, I assumed that was where I was loosing the coolant.

Yup, I have a blown head gasket or cracked head, leaking into the number one cylinder, causing misfires until it can blow all the coolant out.

The this thing has never over heated, or even moved the needle hotter than straight up, normal temp. But it hasn't been driven more than a 30 minute trip, since this started, just a coincidence.

I haven't yet had the chance to take it apart, that's a project for next weekend, if all goes according to plans...


One question, the stupid thing needs cats too, would you bother to replace them now, or wait until I have a smog due next year (November)?

[SlickGT1]

Subscribed. You are on a good path. What color was the smoke? Wait to do the cats later. Why do you want to replace them?

If you do replace cats, make sure you take yours to the metal scrappers yourself. Chances are, there be platinum in them cats. Read, big bucks.

[bastereo]

The smoke was white, just like normal condensation from the exhaust.

The car has been throwing catalyst codes for both banks since before this began.
I was thinking of doing the cats now only because the head comes off easiest with the cats attached, they are difficult and time consuming to remove. That says something because I'm fine pulling the head...

There are core charges on the cats, so I can't recycle them.

Sent from my SGH-i917 using Board Express

[SlickGT1]

Than to me, you answered your own question. Replace the cats now. If they are a huge bitch to remove later, you might as well do them now. Take lots of pics.

[bastereo]

Well, no pics, sorry.

Job is done, I went cheap, skipped the cats for another year.

The bad news is that the machine shop said the head had already been milled/resurfaced once. Meaning that now my cylinder head is at the minimum, and (more bothersome) why did this engine have a second head gasket failure?

Anyways, so far so good.

I was able to removed the cylinder head with the manifolds still attached. I did have a couple extra bodies to help lift and maneuver. The head with both cats barely fits out. And if you are not careful, you will do like I did and break the timing chain guide when you pull the head forward.
But the guides and timing cover gaskets cost less than $50

Now its all buttoned up and running great for 2 weeks now.

[SlickGT1]

That is good news. At least it is a 3.0, and you can source a new engine / parts fairly cheap.

[Michaelj]

I've searched and cannot find a diy for a cylinder head removal for an e53 S54 engine. Does anyone know of one? Another symptom I've had is that I'll get a low coolant warning about every three weeks but when I open the expansion tank it fills up and the level returns to normal.