Hello, friendly Mercedes folk...Is there any way to isolate a bad injector other than the old "screwdriver-to-the-ear" trick? 259k, runs beautifully, but now and again at a tollbooth the idle drops.

Also, steering has been stiff lately. I don't mind stiff steering, but others have commented on it; every now and then, the steering colum groans lightly as it's turned. Should I change the power steering fluid?

Last question: there is a vent at the back of the well underneath the driver's armrest. The vent faces the back seat and blows absolutely frigid air all the time, whether the heat is on or off. I am in Boston in the winter--this may cost me friends!

Injectors will not cause idle to drop or deviate. I have seen where the engine harness will rub the intake and wear a hole in it. Every once in a while, it will hit and cause a low idle.

The center vents are for A/c only and should be turned off in the winter.

The heat comes out via vents under the seats.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Benzmac, thank you for your advice.

The only thing I'm still a bit confused about is that cold air--my car doesn't have an ac compressor at all--it was pulled out entirely, and I haven't bothered getting another one.

And I can change the power steering fluid? Or rather, my boyfriend can?