Not too difficult when you have misfire with fuel cutoff on 3-4 of 6 cylinders and after one bottle of injector cleaner they all go away.

In wife's case I was getting misfire on just one cylinder so I swapped a couple coils and the problem moved. I changed that coil and then got a misfire on a different cyl. Swap coils problem moves, change that coil. Happens a third time. Thats when I ran the cleaner.

I always put the cleaner in just before putting in 8-10g (not really half a tank). It seems to be concentrated enough. On more than one occasion I would get misfire on heavy throttle and the problem would go away on the first treatment.

I usually use Lucas but they happened to have STP brand and so far so good. No lean codes in about 90 miles of driving. I would usually get within five miles.

I still think my cat is nearing end of life or my MAF is overdue replacement so I won't be surprised to see the lean code return but the surprise was the cylinder misfire.

I also haven't change my fuel filter yet so even though they should last 1/4 mil miles or more when I changed wife's at 180 or so it was very very black on the dirty side of the paper. Not expensive enough to not change.

I don't use more concentrated on purpose I think time is an element of good cleaning and a couple hundred miles of driving with that 1/2% seems to do a good job and I've been using that method for 4-5 years.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)