89 454, dieseling, run on when shutting down.

[JerryP]

My 89 Chieftain with 454, sometimes seems to diesel, /Run on after I shut it down, for a long time.
I removed the AIR system, and most of the vacuum lines, leaving only the Distributor vac, and Automatic tranny vac line.
Plugged the 8 holes in the exhaust manifold.
I am assuming it is likely a timing advance issue, but wanted to check and see what others experiences have been, after removing so much.
It never dieseled before.

[Rickf1985]

It will be running hotter without the EGR, what is your idle speed? Is your idle set too rich?

[Hahn007]

I too have issues with run on especially with a hot engine.
I finally resorted to just shutting the engine off with the transmission in gear.
The extra load stops the crankshaft immediately after turning off the ignition.
Just be sure and remember to shift fully into park before letting off of brake pedal and getting up.

[Rickf1985]

That means you are idling too high. Idle too high and too rich are a perfect combo for dieseling.

[Hahn007]

Idling right around 600-650.
Coach doesn't creep in gear.
It only seems to have the problem in hot weather or right after a hard pull.

You could be right about the mixture though.
It is slightly on the rich side I think...

[legomybago]

I too have issues with run on especially with a hot engine.
I finally resorted to just shutting the engine off with the transmission in gear.
The extra load stops the crankshaft immediately after turning off the ignition.
Just be sure and remember to shift fully into park before letting off of brake pedal and getting up.

I do the same thing on our P30 rig..Ours doesn't seem to diesel as much when you turn the electric fuel pump off first before you shut the hot engine down....I know, I know, I should check fuel pressure W% It's on the list.....

[cncsparky]

Leaky well plugs on the quadrajet needs checked also. 

[legomybago]

Leaky well plugs on the quadrajet needs checked also.

I've never had a Q-jet apart yet myself. I have read up on them some, and they are common for the well plugs leaking, but they also say you will have a "really" run rich issue, and "terrible" fuel mileage associated with this too? Mine runs well, and mileage is acceptable. But I do agree that early stages of these plugs leaking could very well cause dieseling. Maybe someone will go into detail some more on this.

[tiinytina]

Gone Diesels occasionally.. so yes I stop her in gear then shift to park.  Edelbrock new right after we bought her.. 7.4 mpg is average.  I have nto played with the setting to lean out  etc.   she runs like a top though I don't have a tach to tell you exact....
Tina