I have a 88 Gt with a 2.8 automatic and I'm having a over run problem when i turn off the ignition. Can a bad valve adjustment make this happen? After doing the valve adjustment this started to occur. I also pulled the steering column and disconnected the Plugs on the column. everything was plugged in very nicely so didn't think to much about it. Could this be a problem with the timing? Im kinda stuck.

Lots of carbon in the combustion chamber plus low octane fuel. Fill up with premium and run an injector additive.
Retarded timing may be making the problem worse...but it's not doing this on it's own.

edit: your engine should run on 87 octane....but some regulars are better than others....

[This message has been edited by Gall757 (edited 05-28-2014).]

is this what we used to call Dieseling? Because if it is, running on its own after shutting the engine off it was generally caused by bad timing.

Steve

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Technology is great when it works,
and one big pain in the ass when it doesn't



Detroit iron rules all the rest are just toys.

So if the valve adjustment was done wrong could it create this problem. I will check the timing and put fresh fuel in it as well.

I can understand the carbon providing the fire but where is the fuel coming from to allowing dieseling in an electronicly fuel injected engine? timing or not.

Dieseling is caused when you have fuel, air and heat. Fuel can either be gas, or in extreme cases oil. In older engines, dieseling wasn't uncommon when you shut the engine down, but that's because you had a mechanical fuel pump feeding fuel to a carb. With modern engines the ECM cuts off the ignition and the injectors, so dieseling is rare. So it's possible that you have a leaking injector or worn rings / valve guides. You should also check your timing and PCV valve. (as a starting point...there are other possible items that when warn could contribute.)