ignition boot miss
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Evolved Member
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Joined: Jan 2004
Posts: 2,680
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From: Bellevue. WA
ignition boot miss
I'm pasting from another site, this is a line of thought I have never considered.
prolly more to do with high powered ignitions than stock, but still worth the time.
A 280Z-L28 (3.0), Jeff P. owner, stock intake manifold, turbo upgrade, good parts inside the engine.
The ECU-882C-2 EMS, IGN-1 coils, 60-2 crank target, our Platinum fuel pump, and new stock Nisson plug wires were intalled.
The car was put on the rollers, first power run 12 lbs. produced over 400 RWHP. The boost was raised by 5 lbs producing 487 RWHP, engine ran sweet !
The boost was raised by another 4 lbs. producing 512 RWHP though there was a slight miss.
The "object" MAP Dwell allowed for "dwell" increase under boost, reset from 1.3 TO 1.6 (1.6x 3.0 ms=4.8 ms). The next run produced ONLY 462 RWHP, the miss became pronounced.
Another run, I reduced the MAP Dwell back to 1.3, 476 RWHP with a steady mixed cylinder miss.
We all stated that it was bad plugs or wires EXCEPT Jeff as he stated "they were new Nisson OEM". The plugs & boots were inspected, no Silicon grease was found.
Grease was INSTALLED, dynoed, the miss was still present.
The wires, plugs, coils were "bench" tested in my CO-2 chamber, 300 psi allowed us to see the spark cross the boot end then flow into the plug steel body.
At that time NO spark was viewed inside the chambed port window.
The boot was then inspected under my microscope by cutting it in half, then looking at the area that was in contact with the sparkplug.
We FOUND "carbon tracks" along the inside of the boot, conductive paths that "shorted" the boot.
New boots were installed along with new wires, CO-2 tested to 600 psi., full spark all the time in the viewing window.
The 280-Z was dyno tested and produced 523 RWHP@ 22lbs. NO miss was heard.
What was found:
A spark boot can have hidden damage, be damaged by lack of grease, be damaged (unknown) then grease added, AND produce engine miss.
The sparkplug boot should cover the sparkplug from the tip to the steel AND be greased correctly.
prolly more to do with high powered ignitions than stock, but still worth the time.
A 280Z-L28 (3.0), Jeff P. owner, stock intake manifold, turbo upgrade, good parts inside the engine.
The ECU-882C-2 EMS, IGN-1 coils, 60-2 crank target, our Platinum fuel pump, and new stock Nisson plug wires were intalled.
The car was put on the rollers, first power run 12 lbs. produced over 400 RWHP. The boost was raised by 5 lbs producing 487 RWHP, engine ran sweet !
The boost was raised by another 4 lbs. producing 512 RWHP though there was a slight miss.
The "object" MAP Dwell allowed for "dwell" increase under boost, reset from 1.3 TO 1.6 (1.6x 3.0 ms=4.8 ms). The next run produced ONLY 462 RWHP, the miss became pronounced.
Another run, I reduced the MAP Dwell back to 1.3, 476 RWHP with a steady mixed cylinder miss.
We all stated that it was bad plugs or wires EXCEPT Jeff as he stated "they were new Nisson OEM". The plugs & boots were inspected, no Silicon grease was found.
Grease was INSTALLED, dynoed, the miss was still present.
The wires, plugs, coils were "bench" tested in my CO-2 chamber, 300 psi allowed us to see the spark cross the boot end then flow into the plug steel body.
At that time NO spark was viewed inside the chambed port window.
The boot was then inspected under my microscope by cutting it in half, then looking at the area that was in contact with the sparkplug.
We FOUND "carbon tracks" along the inside of the boot, conductive paths that "shorted" the boot.
New boots were installed along with new wires, CO-2 tested to 600 psi., full spark all the time in the viewing window.
The 280-Z was dyno tested and produced 523 RWHP@ 22lbs. NO miss was heard.
What was found:
A spark boot can have hidden damage, be damaged by lack of grease, be damaged (unknown) then grease added, AND produce engine miss.
The sparkplug boot should cover the sparkplug from the tip to the steel AND be greased correctly.