Run on ?

One of the things I was always happy about was that my 01 ALH engine started and ran very smoothly. This morning, it began a small "run on" after I turn off the key. It's never done this before and now it does it every time I shut it off.

Engine tries to shut off when key is turned but has a burp of life after... then stops. Where to begin looking to solve this? Thanks in advance for any advice.

Check to make sure your ASV valve is working correctly, its called anti shutter for a reason.

There's a valve in front of the intake manifold called the ASV (anti-shudder valve) who's sole purpose in life is to ensure smooth shutdowns, so starting there would be my first thought.

If you search a bit you should be able to find some good threads on ASV troublehooting, with pictures etc... it's vacuum actuated with a black plastic actuator, an N75 valve, and some hoses.

Typical failure modes are leaks in the vacuum tubing or the small plastic arm that pulls the valve closed breaking or popping off.

Great! Thanks fellas. Much appreciated.

If the ASV checks out then I'd take a look at the fuel shutoff solenoid.

yeah, I'm not sure if those with a deleted ASV experience a little 'dieseling' after shutting down - i was under the impression not. I mean, the intake mani holds a volume of air so even if the ASV shuts and seals, I would expect it would 'diesel' just on that air alone.

but it is easy enough to check, and the whole thing may be gummed up with soot and oil anyways, so why not look in there first.