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Discussion Starter #1
I've been having some intermittent detonation problems still and finally got to pulling my plugs out. All of them looked normal except #6. It was burned/melted and had hard ash deposits on it. That would be consistent with the small amounts of detonation I've been hearing on longer trips after my engine is fully warm but I'm not sure why it's happening on only this one cylinder.

Since it's just one cylinder that should rule out O2 sensors, vacuum leaks, intake problems, ect. I'm thinking it's either a problem with the plug itself, plug wire, coil or possibly injector. Is there anything else that I should be concerned about or check?

I have another set of new NGK TR-6 plugs that I just put in. I'm waiting on plug wires to arrive as one of the wires on the other side of the engine came apart when I pulled it off. I'm not sure if this would be related to the problem at all but it needs to be replaced.

Any insight would be appreciated.
 

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MOAR BOOST
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Replace the plugwires and plugs and see what happens. if one fell apart when you pulled it off it might be safe to say some of them are bad.
 

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Discussion Starter #3
Replace the plugwires and plugs and see what happens. if one fell apart when you pulled it off it might be safe to say some of them are bad.
They're 11 years old so yeah.. Time to replace them with some new AC Delco ones.
 

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if a new plug and wire doesn't fix it, i think you better check the compression of the cylinder before you do some serious damage. Your running FI so you really cant afford to be driving around with any sort of detonation, its a disaster waiting to happen.

also what are your plugs gapped to?
 

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Discussion Starter #5
if a new plug and wire doesn't fix it, i think you better check the compression of the cylinder before you do some serious damage. Your running FI so you really cant afford to be driving around with any sort of detonation, its a disaster waiting to happen.

also what are your plugs gapped to?
Yeah, hopefully the new plug fixes it. They're all gapped to .032 as were my last ones. The gap on the detonating one is quite a bit larger now but the rest were still within .030-.035.

I've never really been in detonation while in more than 1lb of boost. When it seems to be happening I make sure to back off the throttle until it stops.
 

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I've been having some intermittent detonation problems still and finally got to pulling my plugs out. All of them looked normal except #6. It was burned/melted and had hard ash deposits on it. That would be consistent with the small amounts of detonation I've been hearing on longer trips after my engine is fully warm but I'm not sure why it's happening on only this one cylinder.

Since it's just one cylinder that should rule out O2 sensors, vacuum leaks, intake problems, ect. I'm thinking it's either a problem with the plug itself, plug wire, coil or possibly injector. Is there anything else that I should be concerned about or check?

I have another set of new NGK TR-6 plugs that I just put in. I'm waiting on plug wires to arrive as one of the wires on the other side of the engine came apart when I pulled it off. I'm not sure if this would be related to the problem at all but it needs to be replaced.

Any insight would be appreciated.
It's pretty much normal for carbon to build up in the back cylinders #3 and #6 and cause preignition due to the design of the pcv system. The only thing to due is to decarbonize with something like seafoam (or I heard Ford has something). Then replace the damaged plugs. Also replace the wires.
 
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