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Old 10-21-2012, 08:22 PM
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Join Date: Nov 2011
Location: Livermore, CA
Posts: 295
bastereo is on a distinguished road
Cold start misfire

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)?
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