Hello,
I have a '92 244 that I am trouble shooting for an Idle issue. The car has no problems cranking or firing up, but once it begins to run, the engine shakes around quite noticibly and causes vibrations to be felt throughout the car. It is strongest when it has not been running for several hours but never completely goes away even at peak opperating temp. There is no problem with the engine wanting to die, it's just an annoying shake that happens about every three seconds, give or take.

While its running, I also can feel a vibration in the steering wheel and matched to that vibration I hear a very low buzz every second or so. It is almost a pulse so I wonder if those are the fuel injectors opperating. The car does have 160,000 miles on it so I guess I should expect some engine vibration but after driving my brother's SAAB it got me thinking...

Any ideas on what the shake could be caused by? The throttle body is clean and the fuel injectors were cleaned, though not with a machine. I've heard that it could be unmetered air leaking through to the intake but I can't find anywhere where it could get in, even that accordion hose. Would a single injector with a bad spraying pattern cause a noticable shake every three seconds? Any ideas are appreciated.

Thanks
Jonathan