I have a 2000 3.8 liter V-6 mustang that has started making a knocking sound after I turn the engine off. It will knock several times after the car has been turned off and then stop. I have not detected any such knocking until the engine is turned off. It doesn't do it upon cranking the car, it doesn't do it while driving or stopping at traffic lights, etc, only after the car has been turned off. Any thoughts or ideas? Any suggestions would be greatly appreciated. Would just like to have a general idea if I take it into the dealership in the next few days.

 

in the old days it would indicate that the timing was set to high. but on these computer cars, i do not have a clue. good luck

 

I didn't know that was possible anymore either until I looked it up in a Haynes manual.

The causes might be;

1.Idle speed too high.

2.Ignition timing incorrect.(probably not)

3.Incorrect spark plug heat range.(?)

4.Vacuum leak.

5.Carbon build-up in combustion chambers.(more likely)

6.Valves sticking.

7.EGR system not working correctly.

8.Fuel injection or ECM malfunction.

9.Possible overheating.

Try getting any fault codes read at Advance or Autozone and repost.

Cleaning the combustion chambers is a fairly simple operation where you spray lots of carb cleaner into the engine and let it burn and blast the build-up out the exhaust.

If you decide to do it yourself,repost and I'll give you a workable method to do the job.

 

Hey a question for the original thread creater. Do you have any driving problems? For example, I have a 1995 3.8L V6 and my engine will knock after I shut it off. Never hear the knocking during operation or when cranking, nothing. Never hear it in till I shut it off. I have been noticing my engine driving as if it seems out of breath. Like when I accelerate it'll like shutter in till I press hard enough where the RPMS will shoot up intill 2000 and then I have no problem going. I'm starting to think maybe they are related. I have no OBDII issues, no transmission, nothing. No codes, no nothing. I have had my car checked out several, several times by different shops and specialist and no one can solve this problem. Did you find anything?

 

this thread is over half a year old dude...im sure he has it fixed by now.

 

Agreed! - I thought the same.

 

You need to change your spark plugs plug wires and i would suggest your coil pack as well its your spark plugs not handling the engine heat do it dies and doesnt give spark.

 

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