About 6 to 8 mo's ago my taco started have some light ping (when pressing throttle about halfway before the downshift) so I started running 89. Now it does it on 89 and if I put 87 in thats all it does. Was gonna take it to the dealer next saturday.

Just wondering if anyone has any ideas. The fuel filter has only 10k miles on it, it has ngk plugs and new wires with less than 10k miles. THe manifold's been cleaned with power foam and I run only chevron gas with techron additive every oil change. No c/e lights also. Truck appears to run fine beside the knock and its getting bad.

 

Could be carbon build up in the cylinders.It can happen with age.It builds up on top off pistons raising compression.Not the only thing that can cause it but one reason.

 

Carbon build up is a good one... have you tried cleaning the MAF sensor.... if the computer thinking that you are getting less air it will fuel for less air.... lean mixture.....

Are you by chance running a K&N air filter???

 

I cleaned the MAS about 15k miles ago and could try that again. Funny thing is it's only bad on the really warm days, but at night and cold days its fine. I am not running a K&N, just a wix air filter with the air box mod.

Is there a chance the fuel pump might be going out, I'm pretty much grabbing at straws now but I gotta figure out something soon because it was warm today and it was ridiculously bad.

 

What would be the remedy for carbon buildup on the cyclinders?

 

Think I might have found the problem, I decided to get out there tonight with a flashlight and pull out the MAS. What I found might have been a goof on my part when I cleaned it last year after buying it used.

All I cleaned was the red bulb that is visible(which was pretty dirty again), not the two thin wires up inside the MAS. The wire that was farther back was pretty easy, but it took a lot of electrical cleaner to clean the closer one, it almost seemed to have a crystal like hard substance on it.

After some good spraying both wires are clean and shiny and the truck is running good. Hopefully when I get back in town Thursday and can actually drive it around town in the heat the problem will be solved. I can say though, that the MAS wires were very very dirty.

 

if you think it's carbon buildup, then you can use some SEAFOAM to help that out. do a search for info.