Misfire on No.7

[David Potter]

Im getting to the stages where I’m going to start pulling my hair out about this misfire.

From the top.

I had a lean code, lean on both banks. Found some hoses off to the pcv so reconnected, believe the fault was sorted.

Next up I got a bad misfire on number 7, first off I swapped out no.7 coil for no.1. The issue remained with no.7

I then replaced the all the plugs, I purchased these a while back but never got round to fitting them. All the plugs had signs of the engine running lean except no.7 which was black (rich).

I used a NOID light and confirm no.7 injector signal is good.

Also checked the spark through the coil with an external ground. Which was good.

I’ve looked on youtube and the sound it makes is much like the popped plug videos (striped thread). The plug seems tight in the thread, how can I prove or otherwise if this is the case?

 

[David Potter]

Sorry, car is a 2004 5.4 2v.

 

[Sgt Darkness]

Wow nobody replied to ur question....if u have a timing light u can check to see if maybe it might be the plug wire. You may have checked it already but u didn’t mention it in ur question. Hopefully you have the problem fixed by now.....

 

[Trainmaster]

A NOID light woun't tell you the injector's working. It could be leaking.

If the injector checks out, it's probably time for a compression test. How many miles on this old gal?

 

[Sgt Darkness]

A NOID light woun't tell you the injector's working. It could be leaking.

If the injector checks out, it's probably time for a compression test. How many miles on this old gal?

Yea a leaker or bad compression on #7 will cause the plug to look bad. I agree it may be time for a compression test.

 

[Adieu]

Injector signal ain't injector mechanical performance, afaik

Swap over another injector and see if the code moves after clearing

 

[David Potter]

Sorry forgot to mention I’d previously swapped the two injectors over to eliminate that.

Whipped the rocker cover off to have a look and discovered this. Cam looks to be OK but I’m going to have a proper look another day. What’s the odds of no damage and being able to put it back together and carry on?

 

[Trainmaster]

Where'd it go?

You're the second one here in a month! Looks like the valve's still there. You shouldn't have a problem. Relatively easy fix, I think. Now check for a broken spring and figure out how to get that all back in there.

 

[David Potter]

It was laid up just the other side of the cam.

 

[TobyU]

As Trainmaster said, check the valve spring to make sure it isn't broken. Check the roller and bearing to make sure it has no lateral movement.
I had one pop out on a 4.6. I went ahead and replaced the rocker and the "lifter" lash adjuster since they were cheap.
I would replace the lash adjuster because even if it feels solid and pumped up with oil now, they can collapse under pressure and speed and let thing slop around and that could cause a rocker to pop out.

I would also fire it up for a few seconds before I put the valve cover back on to make sure it all stays in place.