I have a spark knockin
97 4.6 4x4 w/ 189k miles.
Its not the brand of gas
its not the plugs
its not the air filter

I was woundering what ya'll thought about trying some octane boost before trying 89 or 93 octane gasoline?

 

I'd try the old Seafoam through the intake procedure first.

Steve

 

What is that? I haven't heard of it before

 

Try cleaning the MAF. If dirty, it could cause a lean condition.

 

octane boost only raises the obtane 3 points , not a big deal. so you87 octane is now 87.3 for the 6.00 it cost you you could put in 3 gallons of premium.

 

Alright that sounds good, the MAF is clean i believe.
I am about a day away from needin gas. I will fill up with 93 and see if the spark knock goes away and see if anything in the truck improves.

 

You can't tell if the MAF is clean just by looking. CLEAN IT.

Then check or verify that you have already checked/changed the following...

Throttle body: EGR PORTS on 90degree elbow (definately in the top 5)
Trottle body should be cleaned as well

EGR: Ensure that the egr valve is operating properly, remove it, clean it and see if the plunger moves freely

Fuel Filter: How long since you changed it?

Carbon: Sea-foam the engine by slowly pouring 1/2 bottle of seafoam into the PCV valve or hose, allow the engine to stall or have a friend turn it off when you reach half a bottle. Let it sit for 15-20 minutes, go for a VERY BRISK drive employing many WOT opportunities. The smoke pouring out of the tailpipe will be carbon. The bottle says to pour the remainder in the fuel tank but whenever I have done this in the past, it pings for the remainder of that tank.