travelinman

I installed the deckplate mod a couple of weeks ago. I had it open for a few days and I noticed that the knock in my S/C'd engine got worse when I was going up big hills. I don't have any of the fuel mods yet (I do have the 2 step cooler Denso plugs). I don't get much knock with the plate closed under the same driving conditions.

I like it deckplate open because off the line the throttle response it noticably better. But, I'm not into killing off my engine yet...

Any ideas why the open deckplate would cause more knock?

I live at 5,400 feet above sea level, by the way.

4RUNR

Are you sure it's not the same knock that you are now just hearing better through that hole?

travelinman

I guess it could be, but it sounds like it's coming from the engine itself...

4RUNR

Doubt you can localize sound to within a foot or so with the hood closed and sitting in the driver's seat

I don't have a supercharger, or knock, but I can tell you with certainty that the noise from engine mechanicals is coming through the deckplate. Sounds similar to a Subaru, especially when driving along a high curb or a wall for it to reflect sound.

TRDOLMAN

If you already had detonation on the truck before doing the deckplate, then the deckplate mod will make the detonation worse. Think about it---you are allowing the engine to take in more air which will make you leaner than you were before. My advice is to close up the deckplate until you do some kind of fuel mods.

Dave

mike_d

knock occurs when the fuel is preigniting. preignition occurs when the pressure in the cylinder is too high, so that when you compress it it gets too hot and the fuel ignites. if you're running an SC with the deckplate closed, it gets less air in the intake, so the initial pressure is lower. when the deckplate is open, even more air makes it in, so the pressure in the cylinder is higer, which can lead to knock.

either close up your deckplate, or lower your boost on the SC (don't know if you can do that) or run higer octane fuel (i don't think there's anywhere to get higer than 91 out here though).

ColImport

why would you need a deckplate when you have a SC??
There is enough talk about 4runners leaning out with just the supercharger and now you add more airflow with no fuel mods??

close that deckplate until you really tune your truck properly or you will run the risk of damaging the engine long term.