Help Diagnose Engine Knock...

[jrobinsonchicag]

I’ve got a nasty tick/knock in the motor. It sounds like a rod bearing. The ECM shows a code that cylinders 4 and 7 are misfiring.

The car has little power under acceleration and sputters very badly. Prior to this all going down, no codes were thrown, but the car would sputter and cut out when getting heavy on the throttle.

Will a bad rod bearing cause strong unburned fuel fumes? The exhaust fumes are terrible.

Video of tick/knock…
YouTube - CIMG2057.MOV

 

[nancygrl]

What year car/engine etc??? I'm sure you'll get others that will probably say check your plugs. Plugs blowing out of the head seems to be a common occurance for the 4.6's

 

[trombonedemon]

I would suspect if you had a bad crank bearing, you would get a high pitch squeal of some sorts, my guess would be fuel or fire, pull the two COPs that are throwing the code to see if the situation stays the same or gets worst. If it gets worst then those are not your problem if it stays the same then they are, you can look up how to test your COPs, I would change those spark plugs and or check for early detonation, there are some tell tale sighns by looking at you plugs.
In addition, just to rule out your bearing issue, change the oil and check or metallic shavings, that would be a major clue.
Also, check to see if your intake and everything that leads to your lower intake is completely tighten, my cold air intake clamp came loose, leaving an extra opening for air to be sucked in and sputtered and created smoked and cut out at times.

 

[trinity_gt]

I’ve got a nasty tick/knock in the motor. It sounds like a rod bearing. The ECM shows a code that cylinders 4 and 7 are misfiring.

I agree, at first glance it seems rod-ish.

Can you localize it to the top or bottom? Left or right? Does it get worse under load?

The car has little power under acceleration and sputters very badly. Prior to this all going down, no codes were thrown, but the car would sputter and cut out when getting heavy on the throttle.

I'm a bit cagey on the rod diagnosis because it sounds almost light enough to be valvetrain. Then again, I'd expect a valvetrain tap to stay constant with revs and this one didn't when you revved it which shouts "rod"...

You've got no power, a couple of misfiring cylinders and a nasty tap: What's the history of the engine? When did this start? Did the tap and the loss of power appear at the same time?