Pre-ignition

2000 Mountaineer with 5.0 has pre-ignition rattle when pulling hills; severe when pulling a trailer or small boat. Have tried octane boost but no difference.
Suggestions?

Welcome to the forum!

Has it been doing this for awhile, or after filling up with fuel? Have you tried fuel from different brands? What grade of fuel are you using? Have you tried a different grade of fuel? And finally, when is the last time the truck had a tune up (fuel filter, air filter, spark plugs, spark plug wires, and even a MAF sensor cleaning)?

-Rod

Thanks for your reply. Been doing this for a couple years now; very noticeable when pulling boat/trailer. Have not tried any fuel other than 87 octane (Shell, Texaco, Chevron). Complete tuneup as of one year ago (fuel filter, plugs, wires, air filter etc.). I would like to know how to clean the MAF sensor. Where is it located?
Thanks for your help. Much appreciated.
Steve

The MAF sensor is mounted in the intake air tube between the air filter and the throttle body. It is held in place by two tamper resistant Torx screws.

-Rod

The MAF sensor is mounted in the intake air tube between the air filter and the throttle body. It is held in place by two tamper resistant Torx screws.

-Rod

-Rod, not sure if I'm replying to your last response correctly...Thanks again for your fast reply. I will attempt to clean the MAF sensor. Do I just remove it and clean the face?
Thanks, Steve

I used to clean the MAF sensor elements (very carefully) with brake cleaner. I'm not sure it's any different, but CRC makes a MAF Sensor Cleaner (smells like brake cleaner/electrical parts cleaner) which is what I use now. The elements are mounted with very fine wires, so be very careful to just spray the cleaner over them and not make contact between the cleaner's straw and the elements.

I don't really think cleaning the MAF will solve your pinging issue, but it shouldn't hurt anything to clean the MAF.

-Rod