JohnLane

Guys my car is officially long enough in the tooth to be due for ignition coils. I prefer to do all 12 of them at once but at over $150ea I'm not up for firing the parts cannon to the tune of $1800.00. Yes; stings less than for those with a 221 car but grrrr....

MB part number is 279 906 11 00. New coil indicates it is manufactured by Delphi but I find no availability for this coil online except via MB.

Lots of Delphi and NGK coils available for other MB products for reasonable $$ online.

Thoughts?

VII

Not necessary maintenance and you can't beat $0 so that would be the recommendation.

JohnLane

I’m getting an intermittent rough idle as one cylinder is dead... also lacking power. At times perfectly smooth with all horses accounted for.

No codes. Plugs are new enough. Wires new with plugs. Good compression in all 12. Burns a quart of oil in 5000 miles.

Not my first bent 12 with no code diagnosis to do.

Katie22

Ignition coils are a very low failure NOt something you should have to change unless there is an actual failure. What does need changed are the rubber boots on the coils which are pretty cheap. Just replaced the rubber boots on my GTC they were 12 dollars each boot.

You could remove the one coil with the misfires and remove the boots on it and carefully put the special grease stuff (diametric grease) on both ends of the rubber boot and reinstall onto the coil and see if your misfire goes away. While your at it remove another and put the one where the misfire was into the other spot. If there is a bad coil it will certainly follow into the new position.

VII

If there is a noticeable misfire check the counter with diagnostics and replace that cylinder only.
Also your idle could be an air leak, you are on the high end of oil consumption so check PCV.

JohnLane

MB kit doesn't catch ANY misfires. Smoke test reveals no leaks. 180-190psi compression in all 12. PCV is all intact. 'High end of oil consumption' for a TT V-12 is a quart in 600 miles. This one consumes a quart in 5000. Better than virtually all.

I'm assuming the MB kit should be able to perform a cylinder balance test. Don't know how to make that happen.

VII

Not better than mine! Jk I don't drive that one enough to add oil between changes.
600 is not the high end, that is the defective end where MB will give you a new engine. I don't think I've ever had an engine consuming a qt per 5000 under normal operation but yes it's not necessarily indicative of a problem.
I would not go for the coils but if you will it seems you'll have to go with the MB branded as no one else is marketing these low volume parts.

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VII

Also advanced idle diagnostics including spark suspension, timing and trim adjustments can help find the issue but it needs to be reproducible.

JohnLane

The dumb thing never misbehaves long enough to catch it in the act with test equipment.