Hello all.

Couple of days ago I start my 03 Dak QC 4.7L and it runs rough... like it's missing on a cylinder. Plus there is a tapping like noise that sounds like fan blade contact (but it's not) which increases with acceleration. Not so much a tapping but almost like one of the cynlinders exhausting out the side of the block.

Anyway, I take it on the road and between 1400 to 1550 rpms it wants to shake something fierce. Below that or above the shaking totally goes away and I am only dealing with a power loss. Losing no antifreeze, no visible smoke the exhaust.

There are few diagnostics codes... the first 3 are all evaporative emissions codes.

The last two are P0300 and P0302... which I believe references the number 2 cylinder. So I put a stethascope on the engine the tapping noise is loudest on the overhead cam above the number two cylinder.

I remove the plug from number 2 and moved it to 4 (4 plug to 2) and the ignition coil I moved from 1 to 6 to see if the codes change to either 4 or 6.
However, I ran the engine with the 2 plug removed and grounded against metal and I got bright spark so it does not appear to be electric issue.

Any ideas what would cause this behavior if it's not the plug or ignition coil for the number 2 cylinder? fuel... or lack of to number 2?

Can oxygen sensor be part of the problem?

Truck has 75,000 miles and is a 2003 Quad Cab 4.7L.

Thanks,

--Rick

 

Pop the valve cover over #2.

It's not that unusual for the 4.7 to break a valve spring or toss a rocker arm.