Cruise Control Issue

Oct 21, 2008 2 Replies
C
87 300D 2.5 Turbo

Today when coming home from some thrifting (hitting the city thrift shops) my cruise turned on max. I couldn't turn it off by hitting the brakes. So I pulled off the road. When I shifted into Park the engine went to a high RPM. I turned it off before it went too high. Restarted right away - RPMs went high, so I turned it off again. Waited 5 minutes (to let the vacuum subside) and restarted. It started fine and the cruise was finally off.



Thoughts on what to check? Or should I just shell out and replace all the vacuum hoses under the hood? ;-)


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W

It sounds like the turbo ran away. There is a air pressure limiter (may not be the right MB term) on the intake manifold, a hexagon about 22-25 mm size. It turns off the signal to the injection pump to stop the extra fuel. The limiter, wire or the vacuum may be in fault.

The operation: The boost from turbo calls for more fuel. More fuel produces more power, faster rpm, more exhaust. More exhaust turns turbo faster and it in turn makes the boost even higher. Therefore, never overlook this safety device.

Cheesehead wrote:

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T

I agree... your turbo safety device is not working or bypassed.

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