This has happened a half a dozen times or so since I bought my 2010 FX4 Screw 4x4 last year. It is the 5.4 Ecoboost.

I did have dual exhaust put on it the week I bought it, Flowmaster 40s with 3" stainless steel tips.

I'll be driving at 30-35 mph with my foot on the accelarator and all of a sudden I'll hear this sound which I'll describe as a chatter. Has anyone ever been driving and caught a tree branch in the under carriage??? That is the first thing I thought of when I heard the noise. But there were no branches in the road.

As soon as I lift off the accelarator the noise stops. So I don't know if it is related to the dual exhaust somehow or if there is something else going on. I am very much a novice when it comes to engines but could this be related to the air intake???

Thanks !

 

detonation...Try 91 or 93 octane...higher octane burns slower..I heard detonation in my 2013 when I 1st got it...added higher octane and it went away.

 

5.4 Ecoboost? That's a rare motor, tell us more.

 

Cam phasers or chain tensoiner its common with the 5.4s no biggie i have some chatter as well jn my 5.4 lemme guess its between 1000-1400 rpms right? And btw its not a 5.4 ecoboost haha its just a 5.4 they never made a 5.4 ecoboost

 

Wait... 2010 5.4 Ecoboost?

 

My bad... I had Ecoboost on my brain from reading some of the posts.... 5.4 FlexFuel.

Yes this occurs a 900-1000 RPMs.

I do run the lower grade octane. It's a $.20 difference here and those $.20 eventually add up.

Looks like the consensus is the grade of octane fuel????

 

I listened to mine as I drove around and I can hear Like a chatter at low rpms. Like when I'm starting off at a stoplight. My truck has 50,000 miles and I've had no problems with the motor and my dealer hasn't said anything about it being bad so I think it's ok. Truly though I'm fine with it, doesn't bother me much.