Hey all,

We're in need of some assistance on a car we've got in at the shop. Here's the scenario:

1992 500SL; Initial complaint was a rough idle, but the car was also due for its 30K (major) service. Completed the service then moved onto the idle problem. A lot of things pointed to evidence that this car hadn't been serviced in a LONG time which we noticed while doing the 30K. Anyhow, we found a number of things which needed attention, as follows:

-numerous vacuum leaks (which was clearly obvious by the high idle and roughness)

-dead injector on cylinder #7 (we replaced all injectors, reset lambda)

-distributor caps and rotors in poor shape (replaced caps and rotors - plugs were replaced as part of the 30K)

-all ignition leads checked out fine

-overload relay blown (replaced it)

-a couple of the air injection elbow connectors were cracked (replaced those)

-replaced any cracked vacuum lines (down under intake - main issue was no vacuum present at the EZL, ran a new line, good vac there now). Reconnected a line under the intake that was off.

-motor mounts checked out fine

Soooo......The miss is gone but we still have a slight rough idle, but it's rather sporadic. We cracked each line at the fuel distributor, had some rusty fuel come out, but it didn't really change anything overall once we "purged" them all. I don't think we have a fuel issue by the way the car is running. We sprayed some brake clean around the nozzle holders and the air tubes (which are still supple), and the idle will clear up. I scrutinized the air tubes carefully and I don't think we've got an issue there either so I'm leaning towards the injector holders. While we replaced the nozzles and seals, we didn't do the holders. Problem is that it's hard to isolate whether it's the holders or the air tubes without throwing parts at it, which we don't want to do. Everything else we did on the car was needed just to establish a "baseline" diagnosis since this car has been rather neglected. Additionally, the original miss was cured (idle cleared when we tapped on #7 injector with engine idling), but this "roughness" is still present....and driving us crazy! Reminds me again why I named my shop MB CLASSIC, not MB MODERN, hehe

Any of you out there with more experience on the M119s please fell free to chime in. Fortunately I've got a W108, 109 and a 113 in there now to keep me sane.

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Regards,
Aaron