Cruise Control Issue

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Cheesehead - 21 Oct 2008 22:42 GMT

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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Wan-ning Tan - 22 Oct 2008 05:22 GMT

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.

> 87 300D 2.5 Turbo
>
[quoted text clipped - 12 lines]
> Or should I just shell out and replace all the vacuum hoses under the
> hood? ;-)

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Tiger - 22 Oct 2008 14:24 GMT

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

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