hey
i have an 85 z28 with a diesel effect after turning off the ignition , does anyone know any good engine cleaners that would clear out my engine ?

 

Does it diesel if you shut down in drive then shift to park? If so, back the idle off a bit.

If not, try messing with the timing. Otherwise a little water does the trick.

 

Maybe you have carbon buildup in the cylinders which are causing hot spots which ignite the fuel mixture. Try slightly higher octane fuel and see if it goes away

 

Carbed 305 by any chance? Your idle is too high, and an engine cleaner will not work. Idle should be no more than 750 in gear, and factory setting in gear is 600RPM, 700 in park. More than likely you have one of 2 problems:

1. A vacuum leak. Inspect and repair any vacuum leaks first.

Or...

2. A choke malfunction. Diagnose the choke. Many times they are either gummed up and can be cleaned with some carb cleaner. Sometimes the choke just needs a little adjusting.