Does anyone else have a truck with a 5.4 3v engine that knocks heavily and intermittently?

I recently purchased a 2009 Expedition with the 5.4L 3V engine. While cruising at 45 to 50 MPH the engine intermittently knocked heavily. It sounded like someone was taking a bat and bashing everything under the hood, it could be felt through the pedal and heard over the radio at higher volumes.

Whenever it happened, I would just floor the accelerator so that the engine would use the max-power phaser position (zero internal egr) and max power spark and the knock would go away.

I had a 1/2 tank of fuel so I topped it off with E85 (100+ octane) so that I'd be able to make it to work and back.

Unfortunately, when I took the vehicle to the dealership the E85 prevented the engine from spark knocking so the symptom could not be reproduced.

For some reason the dealer gave me the TSB about the exhaust cam phaser noise, but the description didn't match what I heard and felt. And that led me back to these forums to see if anyone had and engine with severe knock and had tried high octane fuel to prevent it.

I listened to videos on YouTube and those in which you can easily hear the noise and see the engine shaking, I can 99% guarantee that it's spark knock.

BTW: If the exhaust phaser is moving around enough to make noise, that means the % of internal EGR (which is trapped by using the exhaust phaser) vs fresh air is changing and if the spark used doesn't comprehend that, the engine will knock.

 

Have you hooked up a code reader to see if there's any codes present or stored ones???

How many miles on the vehicle???

Some of the other things to check that may influence a spark knock.....

Clean the MAF
Clean the Throttle Body
Spark plug
Cooling system....fluid level, thermostat, radiator clear of debris

 

88racing,

I have not hookup up a code reader because the vehicle is still under warranty. I will do that next time and keep track. Are there any specific codes that you would expect to be logged after such a knock event?

The vehicle has 30,000 miles on it. The radiator does not appear to be obstructed. I'll have a look at the spark plugs if the dealer doesn't. Might as well change them before they get stuck

Thanks.

 

You can hook up a code reader and read the codes without voiding the warranty....just dont clear them.....if you still have warranty....its dealer time...

 

The plugs in a 09 don't get stuck, it has the redesigned heads.