When I "punch it, or just accelerate alot i hear a rattleing sound. I have no clue what this is. Any ideas????

 

Could this noise the the common 4.6l pre-ignition ping?

 

This is your ping for sure, do a search you will dig up a lot. Good luck.

 

If it's not from your internal engine, maybe it's your exhaust heat shields?

 

Also, my "Check Engine" light comes on and off. It will stay on for a day or two then go off for a while????? Maybe something to do with it???

 

As mentioned, the noise your hearing is pre-detonation (pinging.) You didn't mention what year you have or the milage. Goto Autozone to begin with and get them to check your codes for you on the Check Engine light for free, and report the code back here. Odds are the two are related. There are a lot of possibilities that could cause predetonation. I would look into correcting what is causing your problem with the check engine light first, then if that does not correct your problem with pinging go from there. If you want to make sure that the noise your are hearing is predetonation, try filling up with a tank of 89 or 92 octance gas and see if it corrects your problem. Although this is just a band-aid for your problem, assuming it corrects your problem with pinging, you will know predetonation is your issue. Possible causes range from something as simple as 'cheap' gas, a dirty MAF sensor, dirty air/fuel filters, issues with ignition plugs/wires/coil packs,) and clogged EGR or Thottle Body, to a flaw in the computer program, among other things. Occasional pinging can be an aggrevating and time consuming problem to solve. Best of luck...

 

Hey, my truck has started rattling only when at idle; it's obvious to me that it's coming from the under-carriage (and is not from the engine or suspension), and it's gotten more noticeable over the last month since it started. Is rattling exhaust heat shields common? Is it pretty easy to tighten up?

Thanks,
Chris

 

I had the problem with my heat sheild some time ago. It's pretty common for the welds to break on the sheild and cause the rattle. It's only on there as an off road shield for high grass. I just had the muffler shop pull mine off and they didn't charge me anything.

 

Had the same thing happen to me recently... I don't know if I have the off road shield...but Ford fixed it.

 

Hi Naviman,

My F-150 was lowered: I can't really go over a speed bump without worrying about bottoming out. Therefore, I can't imagine setting any fires while off-roading: guess I'll pull it off.

Thanks,
Chris