06 Freestar 4.2, under medium to hard acceleration load in any gear I am getting "ping" as dealer puts it. Sounds to me like valve float or piston knock. They tried to say octane...I use 87 as recommended, they said change gas station.....wife does not use the same station regularly. I am thinking that it is possible the intake runners fluttering as this happens exactly between max torque (268 @ 3650rpm) and max horse (201 @ 4250rpm). It is not easy to here and you have to get on it to here it.........Anyone have anything like this.........................PS bone stock no mods............

 

Couple of possible things to look at depending on driving habits and mileage. Could be"HIGH RPM LEAN-OUT" caused by dirty injectors. Have you run any type of quality fuel injector cleaner thru your buggy? Could also be caused by carbon buildup in the combustion chamber. This is normallycaused by constantshort drives where the engine doesn’t get to operating temperature or the engine never reaching high RPM’s. I use AMSOIL's P.I. fuel additive to keep my injectors clean (I still run 1 oz./10 gallons even on their new formulation) and my water injection eliminates carbon build up in the cylinders. But that's just me and my way.

 

I first noticedit around 4-5kmiles but was not able to nail down how to get dealer to repeat,now have 22k and can make it repeat if driven as instructed. The RPM range is only in the 60 to 75% range. The engine pulls strong through 5200rpm. I live in NJ and daily trips are short distance long running ie average speed for a daily drive is 20 to 30 mph and the engine does get to full temp. High RPMs are usually reach due to accelerating on and off highway.

 

Hmmm...got me...I'm at almost 40,000 miles on my 2004. Only noise out of my engine is fuel rail knock when the engine is cold, but that slowly goes away as the engine warms up.

 

Like I said I think the intake runners are oscillating as it is a the point the engines is producing peek power output and the intake runners are used to tune the intake for max performance...........

 

Looked in my Freestar shop manual and could not find a knock sensor which would prevent the engine from pinging so I would take the advise of the dealer and use higher octane gasoline.
Also the advise about the fuel injectors by "use common sense" no pun intended sounds sensible to me.

 

I have the same think on my 2006 Ltd. In reading other forums, this is not uncommon. Higher octane does not fix the issue. Bummer Ford engine design.

J

 

Try the fuel system cleaner like he said, stay away from discount gas, and check and see if the MAF senor is dirty(the wire.) Also , have you changed your fuel filter?

 

I have had the van severiced at 17k, at which time I believe the fuel filter was replaced. The van is well kept in general. If it was "knock" it would happen at any engine RPM under load correct???? This happens only between 3600 and 4200and must be under moderate to heavyaccelerating load, IE it will not do it if you are rolling 3800 RPM costant even under load. And I have dropped Lucus fuel cleaner in the van...................

 

If you have exhausted all other possibilities and suggestions on this forum I would look at something loose somewhere and maybe you are dealing with a rattle and not a pinging condition which as other members suggested can only occour under load. I find the intake runners fluttering a bit far fetched as there are lots of these engines and it would be a more common problem. Of course anything is possible.