Why does my engine sometimes "diesel" after I turn it off?

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Aug 1, 2019 | 07:39 AM

#11

98hotrodfatboy

Seasoned HDF Member

Joined: Mar 2010

Posts: 21,117

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From: Poolville

On hot days a high idle can cause this at times... Do you have a tach to properly set the idle speed.. I like 950....

Aug 1, 2019 | 07:48 AM

#12

TwiZted Biker

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Joined: Mar 2009

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From: Niles Canyon Ca.

Quote:

Originally Posted by Windseeker

I forgot this detail when I posted..... it only does this about once every 5-6 times I shut it off, so it's not a consistent thing.

As for gas, I only run 87 octane, but it's always ethanol-free.

Bump up the gas grade and or tweak the timing back just a hair, cheap gas is going to knock period. Might also close the gap on the plugs a couple thou.

Aug 1, 2019 | 08:36 AM

#13

Tom84FXST

Seasoned HDF Member

Joined: Nov 2009

Posts: 15,705

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From: Farmington ,MS

Quote:

Originally Posted by 98hotrodfatboy

On hot days a high idle can cause this at times... Do you have a tach to properly set the idle speed.. I like 950....

Most "run-on" can be cured by lowering the idle speed..

Aug 1, 2019 | 10:58 AM

#14

Windseeker

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Joined: Jul 2017

Posts: 4,698

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From: Behind you, making faces

Quote:

Originally Posted by TwiZted Biker

Bump up the gas grade and or tweak the timing back just a hair, cheap gas is going to knock period. Might also close the gap on the plugs a couple thou.

Yeah. My plugs are at the recommended max gap and I need to tweak that. I'll pick up a gapping tool that is NOT the disc type and adjust them a bit.