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Plug Diagnostics, Anyone?

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Webb

Webb

Senior Member
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Hey all, some of you posted in my last thread about how my car was burning oil, so you may be familiar with where I'm coming from about my plugs. Anyway, I set the valves 4 days ago, and replaced all the plugs at the same time...brand new Bosch Platinums (WR70P). Here are some pictures I took of the set, hopefully you all can glean some information from them and help me out. Click the thumbnail for a much bigger view.

The white you see on plugs 1 and 5 isn't that it's really lean, it's just that no soot has yet built up on them, as it's only been 4 days.



 
Great pictures, Webb - So, 1 and 5 were replaced after the others? #2 & #4 look a bit rich, and #3 & #6 look OK to me.

Mickey
 
I would have to agree with Mickey and additionally ask if you are sure it is firing on all six cylinders. I believe 1 and 5 would have more of a deposit than they do after four days? Interesting pics!

Harry
CT
 
Sorry that I missed the earlier post. Did you take dry and then wet compression readings of each cylinder?

I would tend to agree with Mickey about the fuel mixture being rich, but maybe there is more than that problem if you're burning oil.

I'd like to see those compression numbers compared to each of the plugs. If the readings were good, time to look at valve seals.

Platinum plugs, "IF" firing properly should not be that fouled in a week. I would think that they should look like # 1 & # 5.
 
If I recall correctly, you indicated in a previous post that you didn't have a compression gauge. Based on the condition of those plugs, I'd recommend that you find one and try to determine what's going on there. I suspect that you can borrow one from most chain automotive stores (I know AutoZone has a lend-a-tool program).

The fact that you're getting a range of conditions for plugs on both carbs indicates to me that it's not carb related. Part of it may be ignition related, but 2 and 4 (I think those are the two) look to me like they may be a little oily as well as sooty.

Good luck.
 
Thanks guys. I'm pretty sure it's firing on all cylinders when its running, but it seems to shudder a little at idle once in a while. Looks like I'm back to where I was: find a compression gauge. I guess I'll do that this coming week once I get paid so I can make the deposit on the lend-a-tool program.
 
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