hey guys,

i posted this a while back, but was curious as to whether or not anyone had any ideas...

when i run regular gas (87) and mid-grade (89) in my 4.6, it spark knocks, very noticably, but when i run premium (93), it doesn't...

my two questions are...is there a pressure regulator i can adjust or will a programmer help me?

thanks

 

Let your dealer have a look at it my 5.4 never knocks on 87 oct. I beleive these engines have knock sensors to keep them from doing that your VVT may not be working correctly as there have been some issues with the cam phasers.

 

yeah, its been to a couple of stearlerships now, they either can never hear it or claim that its normal...i know about the cam phaser issue on the 5.4L, but i didn't know the 4.6 had them as well...

 

Ya I also don't know for sure on the 4.6, what kind of gas do you run, I mostly stick with chevron,shell or texaco never have had a knock out of mine.

 

i've tried all brands here, shell, exxon, texaco, you name it, i've been buying gas at the kroger station in town for discounts, but it knocks regardless of brands...

edit: usually when i get gas, i fill the thing up...

another thing i would add, when i run 87 or 89 octane, and its low on fuel (when i say low i mean about an 1/8th of a tankfull remaining, it will sometimes sputter and die on me when i put it in park)

 

Have you tried throwing in a can of seafoam with a fill-up?

 

yeah, as i've seen, that stuff can clean out some carbon...but it ain't doing the trick either...

thanks for the suggestions so far guys, i appreciate it

 

There is no way a halfway good 2005 engine would have a carbon build up problem. It is more than likely a timming issue that is effected by the fuel mixture. The mixture changes by the octane content of your gas. The programmers will adjust this for you but to solve the problem I would start by taking it to the dealer and have them program your truck with the latest revision program from Ford. It does not matter if they hear the knock or not.

 

just thought i would post an image...



that was at 10K...

 

I can imagine what that stuff does to the cats!!

 

That looks like soot from running to rich, not a symptom of carbon buildup in the engine.

 

i have an 04 with 4.6 i too use krogers for the .10 discount w/87 oct. and have never had an issue with knocks nor run-on nor stalling. i have no buildup like you've shown in your pic. and i've just passed 28,000 miles but will go knock on some wood just in case.

 

Normal by product from fuels with MTBE's. Condensation grabs some carbon and blows it out the tailpipe.
Knocking should not be present if the ECM and knock sensor are working propery.

 

I agree with Kevin what you are seeing on the ground has nothing to do with seafoam it is simply condensation from the exhaust system, personally I would not be running seafoam in a new truck you have other issues not related to carbon!!!

 

In another string (High build up of carbon in combustion chamber) it is mentioned that he is running an Edge tuner and burning high-octane fuel. His tunes are off accounting for the exhaust soot and engine pings.