 Carbon on #1, 2, But not #3, 4 |
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| StarBear |
 Mar 30 2026, 09:44 AM
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#1
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Advanced Member  Group: Members Posts: 2,257 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States 
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Doing my driving season prep checklist and notice a modest black carbon buildup on #1&2 plugs; #3&4 plugs looked fine. Wired brushed and cleaned electrodes.
What might be causing the carbon on just the left side? (IMG:style_emoticons/default/confused24.gif) Everything else runs fine though still a bit rich overall based on tailpipe A/F meter reading. (IMG:style_emoticons/default/driving.gif) Thanks!! |
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| StarBear |
Mar 30 2026, 09:56 AM
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#2
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Advanced Member Group: Members Posts: 2,257 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States
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PS: 1.8L.
Also, Replaced the four original injectors late the year before with rebuilt/tested ones from Mr. Injector. Adjusted all valves about the same time; maybe missed the settings on left side valves?? (IMG:style_emoticons/default/biggrin.gif) |
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| wonkipop |
Mar 31 2026, 03:20 AM
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#3
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914 Guru Group: Members Posts: 5,480 Joined: 6-May 20 From: north antarctica Member No.: 24,231 Region Association: NineFourteenerVille
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ignition leads from dizzy to plugs?
how old are they? might be a cause. |
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| Superhawk996 |
Mar 31 2026, 08:19 AM
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#4
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914 Guru Group: Members Posts: 7,767 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch
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| StarBear |
Mar 31 2026, 10:28 AM
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#5
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Advanced Member Group: Members Posts: 2,257 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States
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QUOTE(wonkipop @ Mar 31 2026, 05:20 AM)  ignition leads from dizzy to plugs? how old are they? might be a cause. Rather old. Will check. I think I have a new set. |
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| StarBear |
Mar 31 2026, 10:30 AM
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#6
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Advanced Member Group: Members Posts: 2,257 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States
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QUOTE(Superhawk996 @ Mar 31 2026, 10:19 AM) Yeah; didn’t think of it until after being cleaned and reinstalled. Rats. Modest black carbon. Not fluffy or wet. Wire brush and light Emory paper got it off. |
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| Superhawk996 |
Mar 31 2026, 11:05 AM
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#7
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914 Guru Group: Members Posts: 7,767 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch
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3/4 side always runs hotter.
Hard to say without seeing plugs as they came out but per your OP you know you’re running rich. Not surprising 3/4 side would be a little less so as the plugs run a smidge hotter naturally. |
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| StarBear |
Mar 31 2026, 12:28 PM
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#8
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Advanced Member Group: Members Posts: 2,257 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States
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QUOTE(Superhawk996 @ Mar 31 2026, 01:05 PM) 3/4 side always runs hotter. Hard to say without seeing plugs as they came out but per your OP you know you’re running rich. Not surprising 3/4 side would be a little less so as the plugs run a smidge hotter naturally. Yes, the #3,4 plugs were near perfect - a light tan with minimal buildup. |
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| StarBear |
Mar 31 2026, 06:05 PM
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#9
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Advanced Member Group: Members Posts: 2,257 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States
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Ok; here’s the plan:
1. Replace ignition wires 2. Replace the two plugs 3. One dose of Techron 4. 500 miles then recheck the plugs. Will let y’all know! |
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| StarBear |
Apr 1 2026, 02:20 PM
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#10
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Advanced Member Group: Members Posts: 2,257 Joined: 2-September 09 From: NJ Member No.: 10,753 Region Association: North East States
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Doing an experiment. Put in new #2 spark plug and ignition wire while ensuring #1 plug connector is nice and tight; it seemed a bit wobbly.
Also cleaned the contacts inside the dizzy cap; see pic - problem plug contacts dirt on left; ok plug contacts dirt on right. Will run a while then check both to see if contact cleaned solved both or new #2 plug/wire solved just that one. Stay tuned!  (IMG:style_emoticons/default/biggrin.gif) |
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