Would a misfire cause this? ...>

[not_so_special_e]

This is a 1998 Mercury Mountaineer (SUV)

....it runs and drives and everything works....just the motor started running on five cylinders. I parked it after driving it home and it was making a knocking sound.

Would a misfire create a terrible "knocking" noise...especially when cold? I mean a LOUD one, almost like an exhaust leak? The knocking noise gets less loud and more intermittent when it's ran a few miles and warms up.

That's what's happening on this 1998 Mercury Mountaineer. I read in another post, someone was having a misfire, and tried a bunch of stuff, but fixed it by doing this:

"...I replaced the ignition coil, wires, and plugs and now my truck runs smooth. All the plugs looked the same as the pictures above except for # 2. It was kind of loose and still looked new. I spent almost $200 on everything..."

Thanks! Cuz I have what I believe to be a misfire(believe it's #5 cylinder), but it knocks LOUD!

 

[Gadget X]

Not seeing any pictures. Did the "knocking" stop when you got it running smooth again? The loose plug could have been the cause of the noise.

 

[shadowless127]

Was your Check Engine Light blinking? That's a sure fire way to tell if you have a misfire.

Also the knocking sounds like something completely different, like no oil or timing chain issues.

 

[2000StreetRod]

which engine?

I'm guessing from your post that you have a V6 but is it the OHV or the SOHC? If you have the SOHC V6 and the "knocking" sounds like marbles rattling around inside the engine then you probably have a failed timing chain related component. Why do you think cylinder 5 is misfiring? Do you have DTC P0305?

 

[not_so_special_e]

Was your Check Engine Light blinking? That's a sure fire way to tell if you have a misfire.

Also the knocking sounds like something completely different, like no oil or timing chain issues.

*It is a V6...check engine light's been on forever.

*Spark plugs were pulled 1x1 until #5 was found to have no spark(that is, if number 5 is the middle one on the driver's side).

*I'm at work atm, but will check to see if it's the OHC or SOHC engine a lil later when I get home.

Sadly, 2 people have said timing chain, was hoping a misfire would cause a knock lol

Thanks for your replies! You people rock

 

[rb142]

Misfire creates a tick or thump noise with the associated torque bump, but it does not produce a loud knocking sound. It's possible that you have more than one thing going on.

What do you mean by "#5 was found to have no spark"? Did you actually confirm no spark, or did you just pull off a wire and confirm no [further] loss of torque on the cylinder? Do you have code PO305? What other codes are present?

If this is the SOHC, the loud knocking very likely is related to timing components. If an OHV, it may be something mechanical.