Smokey, uneven idle

[Doug Vazquez]

Hello all,

I hope everybody is having a good holiday season.

When I first bought the car, it idled smoothly, although at too high of and RPM. I adjusted the idle per the shop manual CD down to as close as I could get to 750 RPM. The lowest reliable speed I could get was about 850 or 900 RPM on the dash tachometer. This idle speed was fine after initial start up, but after the engine was warm, it was slightly uneven, like one cyclinder would not fire cleanly every time. The engine has always been somewhat smokey at idle and a little trail was usually evident if one was behind the car.

I have adjusted the valves (all were tight) and ran diesel purge through the fuel system and changed the fuel filters in the last three months. This seemed to be making for easier starts and over all better running characteristics and also I thought the engine was not as smokey, at idle or driving down the road. I have also noticed that when I hit the passing kickdown switch, I do not have the James Bond smoke screen anymore.

Lately the idle seems to be getting a little lumpier, with more smoke. I thought I may try a new rack damper bolt to help out the idle lumpiness, but that would do nothing for the smokiness. I have added Power Service to the last tank full in the "clean injectors" concentration (about one ounce per gallon). Does anybody have any suggestions to offer for smoothing out the idle and alleviating more of the smoke?

Thank you,
Doug Vazquez
Stella, W116 300 SD, 200,000 miles