I replaced the idle rack adjustment bolt on my IP for my '83 300SD, and I think it _somewhat_ helps with being a tad bit smoother idle (doesn't wander anymore), but it's still pretty rough. So what next?

I got a replacement timing belt tensioner spring (yet to be installed), as I changed the gasket a while back and I may have experienced some increased vibration after such.

The compression isn't ideal, one cylinder is around 290 psi I believe, the rest are at 320+ psi. I recently did a valve adjustment twice (maybe worth checking yet again). But I'm not sure if that would cause a noticeable vibration/shaking. It's been warming up recently and I'm afraid it will still exhibit that even when it's 60 degrees outside.

The injectors are definitely worn. I have a replacement Monarck set. I don't have any money to put toward the car any time soon (hoping to sell the car even though I know it needs lots of work, I will do what I can without $$), but I can at least replace the injector tips (using the same shims) and see if the shaking improves at all. Obviously it's a shot in the dark without getting the injectors balanced, but I don't have $100 for the tool or a shop to do it. I thought given the grim situation that at least trying at first might improve it somewhat, as long as I keep the injector internals the same and just replace the nozzles. I know that's just a shot in the dark.

The simplest adjustment seems to be the idle screw. I don't think that was ever adjusted, because it's on extremely tight. Beyond that, though, is there anything else obvious that is within my control? Any adjustments on the IP? The ALDA? Is it possible that the timing chain is stretched and can be adjusted/tightened somehow? Some sort of rundown of easiest to hardest adjustments/replacements would be helpful.

Thanks!

Rough idle can be caused by

motor mounts
trans mount
bad injectors see member
http://www.peachparts.com/shopforum/mercedes-used-parts-sale-wanted/338033-fs-brand-new-injector-nozzles-injector-service.html
fuel pressure relief valve
clogged filters
clogged tank screen
injection pump timing
valve adjustment

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I'd try tank screen by blowing air back into tank,let fuel flow again then put on filter.If this helps for awhile then tank needs cleaning

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1999 w140, quit voting to old, and to old to fight, a god damned veteran, deutschland deutschland uber alles uber alles in der welt

With the "stop" lever on the valve cover, start to slow the idle down. When you do this, your are taking control of the rack away from the governor and the damper. If the idle becomes smooth, you found the problem. If it does not, then it could be some of the issues you've already outlined- and should fix first, barring the low compression.

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'83 300D, 126K miles.

One guy here just totally fixed his shaking idle by changing the delivery valves on his injection pump. Great youtube videos. Before that, he tried many things to no avail.

Just so we're clear, you did experiment with adjusting the rack damper bolt in and out to find the best spot to lock it down? And you did so after 15 minutes or so of highway speed driving, with the car completely warmed up?

As I think I mentioned in response to an earlier post of yours, you have to experiment with the idle speed and the rack damper adjustment in tandem on some cars, to get a smooth idle.

What is the idle speed of your car right now?

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Mac
2002 e320 4matic estate│1985 300d│1980 300td
Previous: 1979 & 1982 & 1983 300sd │ 1982 240d

“Let's take a drive into the middle of nowhere with a packet of Marlboro lights and talk about our lives.” ― Joseph Heller, Catch-22