400 knocks when you cut it off

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Jan 3, 2006 | 07:12 PM

jcg82

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From: ellerbe

400 knocks when you cut it off

Like the title says everytime I cut my truck off if knocks a couple of times. Is this what they call pre-ignition. What can I do to help it. Thanks in advance.

Jan 3, 2006 | 08:07 PM

danlee

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From: Delaware

That is not pre-ignition, it is run-on. Try to cut the idle speed.

Jan 3, 2006 | 08:13 PM

jcg82

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From: ellerbe

Thanks danlee I'll try that this weekend.

Jan 3, 2006 | 11:03 PM

fmc400

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From: Austin, TX

Run-on, also called dieseling, could also be caused by a vacuum leak. I couldn't get my 400 to quit dieseling for anything until I found the carb wasn't down tight enough.

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