3.9 engine knocking
 

hi ,my 2004 3.9freestar 126k, is knocking almost continually on acceleration. just replaced the coil pack because of misses when wet,problem solved. i added some hitest gas and knocking stopped, no codes present. any suggestions to solve this problem? thanks

"Knocking" is too general a description of the sound. But it helps to know that you had a limited success with the things you did.

I would have replaced the spark plugs and wires together with the coil pack.

You could also add a fuel system cleaner like "Techron".


That's for starters anyway.

Two other things come to mind about this time, and they are the EGR system may not be functioning possibly because the ports may be plugged with carbon or the EGR valve may not be working although that should throw a code if bad enough.
The other possibility could involve the knock sensor not retarding timing when it detects the noise you describe as knocking.
Bluewind hit on a good possibility and that could be an accumulation of carbon in the combustion chambers.

hi, thanks for those suggestions , will check them out and report back .the coil pack was cracked leading to the misfires.

Replace the plugs and wires as well. It's a chicken and egg thing. We don't know what caused which part to go bad and what the bad part has done to the other parts.

update,the cam synchronizer going bad caused stalling and was replaced.will report if this improved the knocking problem

replacing synchronizer did improve the knocking problem

Thanks for the feed back! I am glad you resolved the issue.

Happy motoring!