So a little over a month ago my engine started making a weird noise (pebble in a can type rattle) and i did the whole search thing to find out that it was most likely a knock and how to fix it.

So far I have tried putting 91 in and it seems to go away--confirming my belief that it is in fact a knock.

I then: Cleaned the MAF
Cleaned the TB
Changed all the spark plugs to motorcraft SP504's
Changed all the plug wires

Its a 2003 with 94000 on the motor and even after doing all that it still knocks with 87, not as bad as it did, but it still knocks.

I don't mind switching over to 91 if i absolutely have to but do you guys have any suggestions for getting rid of the knock with 87 octane fuel?

 

Take it to a shop that has a BG or Motorvac machine and get a complete intake cleaning.

 

Think it could one of your cams knocking?

 

Not if it goes away with 91 octane, that proves it's spark knock, not a mechanical knock. Also, the V6 is OHV, not OHC, and it only has one cam that's down in the block.

 

Cool I'll give that a shot. Also, every few weeks it will throw a code P1518, the IMRC stuck open bank 1, and then a day or two later it will go away. Is there a possibility these two issues are related since we believe its the intake system thats causing the knocking?

 

I wish you had told us that in your first post............

Get the IMRC fixed.