hi i have a 1997 ford f150 4.6 i bought the truck for 900bucks knowing that there was a missfire, verry clean truck loaded power everything but any way the guy told me it needed an ecm so i bought an ecm and that didnt work so i bought 2 new coils that worked for about 10 min no missfire had alot of power but then it went back to normal so i thought maby i fouled some plugs so i bought all new plugs and that didnt work. then the next day i started the truck up it had its power back for like 5 min that right back to normal and it only has power when the engine is cold or has cooled down. and sometimes the door locks go crazey idk if that has to do anything with it or not but i think that that is kinda weird and also there is a wierd raddling noise comming from the top of the engine idk what thats eather but it dont make that sound when its running good. can someone please help me i dont want to keep putting parts into it untill i find out the problem thanks

 

Any codes?

 

The "weird rattling" would make me want to check for a timing chain issue. I would advise removing the timing cover and inspecting for broken/worn guides or tensioner arms. With enough slack in one of the chains, it will cause the motor to run like ***.

The timing cover is not hard to remove. The only special tools you'll need is a fan clutch remover, and a harmonic balancer remover. You should be able to rent them both for free at Advance or AutoZone.

If all is well with the timing, the next thing I'd do is a compression test. But the rattling noise you mentioned makes me suspect a timing issue.

 

it runs good cold and i dont here the raddling noise but when it warms up it runs like **** but when i put the new coils in it ran great for about 10 mins

 

ya the codes came up as ingnission coil circet but i forgot the codes

 

You need to post the exact codes to get help.

 

They all do that, - the COP ignitions as well. It's just the way the misfire monitor and timing advance works once you erase the KAM. Until it learns it can't adjust for it and keep her healthy at the same time.

Yea we need to know a few things.

1.The DTC's, that is most important at the moment. I'm guessing a PO304, since you mention the rattling. They can make a hell of a lot racket when #4 is missing. The wrong PCV valve can cause that as well.

Other than that, there's a few other things, like timing components, as mentioned or you could of lost a follower, but don't go there yet.

2. Which spark plugs did you install in that 97 ? As long as you use Autolites or Bosch plugs, your probably okay.

3. If you don't have a Motorcraft PCV valve, get one , they're cheap.

4. You should always check the fuel pressure. That's the first or one of the very first things you do with misfire issues. It could be a filter or the pump. When they're running this way, they can make all sorts of noises. So you need to get to the bottom of that. Start with the simple/cheap and basic stuff and go from there.

 

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