Can I pull plug wires
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,116
From: Crossville TN
Sure. It will run a bit rough, of course; but you can compare how it runs 'before' and 'after' each plug cap removal to detect which line is the one with the problem. If you find one that eliminates the "miss", just make sure that you check the plug, the wire, and that specific contact in the distributor cap to find where the problem is located.
Note: After removing each plug cap, place it somewhere so that the opening is at least an inch or two from any grounded surface. Otherwise, it could 'leak' its spark out of the cap and mess up your testing.
P.S. I don't think you want to 'ground out' the removed plug wire. Keeping it "open" (away from metal) is no different than having a completely fouled plug....no spark will occur. Don't know how that will cause a problem for the module.
Note: After removing each plug cap, place it somewhere so that the opening is at least an inch or two from any grounded surface. Otherwise, it could 'leak' its spark out of the cap and mess up your testing.
P.S. I don't think you want to 'ground out' the removed plug wire. Keeping it "open" (away from metal) is no different than having a completely fouled plug....no spark will occur. Don't know how that will cause a problem for the module.
Last edited by 7T1vette; Nov 22, 2013 at 11:30 AM.
Le Mans Master
Joined: Oct 2006
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From: El Cajon California
Tech Contributor
Joined: Jun 2004
Posts: 20,850
Likes: 959
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Sure. It will run a bit rough, of course; but you can compare how it runs 'before' and 'after' each plug cap removal to detect which line is the one with the problem. If you find one that eliminates the "miss", just make sure that you check the plug, the wire, and that specific contact in the distributor cap to find where the problem is located.
Note: After removing each plug cap, place it somewhere so that the opening is at least an inch or two from any grounded surface. Otherwise, it could 'leak' its spark out of the cap and mess up your testing.
P.S. I don't think you want to 'ground out' the removed plug wire. Keeping it "open" (away from metal) is no different than having a completely fouled plug....no spark will occur. Don't know how that will cause a problem for the module.
Note: After removing each plug cap, place it somewhere so that the opening is at least an inch or two from any grounded surface. Otherwise, it could 'leak' its spark out of the cap and mess up your testing.
P.S. I don't think you want to 'ground out' the removed plug wire. Keeping it "open" (away from metal) is no different than having a completely fouled plug....no spark will occur. Don't know how that will cause a problem for the module.
Where possible damage can occur is when the plug wire is open circuited. The coil secondary voltage keeps climbing (as the magnetic field collapses) in an attempt to jump the plug gap, which in this instance is not a .035" gap but actually a very large gap (perhaps an inch or more). While the secondary voltage is going sky high (tens of thousands of volts) at this moment, the primary voltage at the coil C- terminal (which is also the collector of the switching transistor in the HEI module) is also seeing multiple hundreds of volts due to the primary to secondary turns ratio of the coil. The switching transistor in an OEM HEI module is a good robust item, but it's best not to abuse the system unnecessarily.
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From: anchorage ak
I've used a timing light and found misses, some times thats enough, other times I've found that removing the plug wire works, but also found it easier with a set of plug wire pliers with insulation to avoid getting shocked.