Can some please shed a bit of light on these plugs. Getting a flashing SES light and #5 showed the most misfires. Only at cruise when in 5th & 6th. I know the picture is not the best but the darker plug is from # 5. I also pulled the #1 plug for comparison. As you can see #1 is clean and white and #5 is dark and brown.

These are new plugs with on a 100-150 miles on them. So with that I can see why #1 is so clean and nice. Next is a compression check for #5, to see if I have a problem there.


With the excessive brown on the insulator, I am thinking I might have damaged a ring gland, and now getting a bit (blow by) of oil in the cylinder.

Note: had a 1/4 inch of oil in my catch can after the 100-150 miles, can was empty-ed and cleaned when all plugs were replaced.

My A/F is about 11.8-12.0 @ WOT So I am sure it is not a lean condition.

 

Kinda stating the obvious, but could #5 be incorrectly gapped? I would check that, as well as the compression test to see if you're getting blow-by, check the wire to #5 to see that it's not damaged... could be things that aren't so major as damaged ringlands.

 

I had a bad injector so the same thing to #3 for me, it cut in and out. I manage to find it with the help of a tech 1. It drove me nuts for a week. Good luck.

Rob

 

I hope, swapped over the wire and coil to another cylinder going to to do a Auto Tap run tomorrow.

I thought of a injector as well, but I don't think that would be the cause of the dark brown color would it. Looks like oil, but might swap a injector as well if the Auto Tap Run dose not point to any thing.

Gaps are right on,,,

 

#1 looks lean, bleached white porcelain. Both have carbon deposits on the facing of the plug (the flat portion on the end of the threads). Almost looks like you have a timing mark about to show on #1 (the line of color change on the grounding strap), but cant really tell from being so faint.
I recommend you put the plugs in, check it with your Tech. Then taking your camera with you, go do a WOT BLAST, pull thru as long as you can "legally" and safely, a good two three will work. As soon as you get off the WOT, shut the car down, pull the plugs and snap a picture, try to do a macro from the mid-threaded portion up. A nice side shot and a front (holding it so the grounding strap can be seen with the "gap" to one side or another, and for the front use a slight 20* angle looking down at the porcelain with the gap facing you). The WOT blast is necessary for a fueling and timing reading, as well as when you let off if you coast with the engine on it will "wash" away any deposits, timing marks etc.. I will try to remember to check back here, via subscribe, but if you post and I dont catch it in 30min pm me please. Thanks and GL

Charlie

 

Any updates?

 

No not yet, but you will be the 1st to know pic,s PM ect. THANKS for your input-concern.

Chris

 

Well as luck would have it. After swapping plugs, coil, wire. Still had misfire on #5. Preformed a compression check and my thoughts were confirmed. 65psi. 1,3,7 were 150-160. Did not even bother to look at the Rh side.

I new it was only a matter of time, but did not think it would have happened so soon.

 

so now its time to get a leak down tester and see what it really turns out to be.
or you could do the "wet" compression test
my lowest compression reading was 80psi