I've got a strange metallic rattling noise when engine reaches 5000 rpm. No fault codes stored. Sounds like it's coming from the electronic accelerator but my scan tool won't access the EA control module. Any suggestions? Thanks.

I would want to see the controller talk to the scan tool. Aside from that, we have seen quite a few failures of the throttle actuators. A good way to check is get it hot, turn the engine off and they key on. Press the accel pedal down slowly until it makes the noise. It should duplicate while not running.

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

ALL the Bosch electronic throttle actuators have defective insulation on the wires in their wiring harness. If the engine does not pull strongly to redline, but starts hesitating and making weird sounds around 4-5000 rpms. suspect the throttle actuator wiring harnesses (integral with the actuator) on the driver side. It fails first. First check out a second mortgage. These are over $2400 each. Send me your old ones and I will rewire them.

Not sure how many years the problem covers but it is from early 90's through 96 for certain. Also many of the other wiring harnesses in the cars have the same defective iwiring insulation. The stuff turns to crumbs continues to work until the harness flexes. Then intermitent failures and shorts.