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testing coil packs/module?


Guest ekvh

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Guest ekvh

My 88 developed a miss last night 120 miles from home. I pulled a wire at a time at the coils and found the number six to have no juice. I put a spare plug in the other end, grounded it, and still nothing. Do I need to do any more to check that coil? the module is not "oozing." I plan on doing the Padgett Delco upgrade anyways, but could this be something else? I figured I could drive it home on the five cylinders the way it was, but called my mechanic and he said I might wash the cylinder clean, thin out the oil and wreck the motor, so I pulled the injector harness for the number six cylinder and drove it home. It was surprisingly smooth if I kept it out of overdrive. BTW I reconnected the harness to the injector this morning to see if it was a heat related failure of the coil and it still missed at 49 degrees.

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Is the other wire connected to the same coil getting fire? Both wires on each coil fire at the same time. If one is getting fire the other should be. I would swap wires and see if the miss follows the wire. If so replace the defective wire.

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It is possible for an open coil winding to do this (not the ICM) but you have to replace the entire coilpack to find out.

There are also some mechanical faults that can act this way but let's try electrical first.

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Guest ekvh

Ronnie, I'll try that after work today. I did all my testing last night under a street light. Wires are fairly new, but that means almost nothing now-a-days.

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Guest kennyw

This system is called a lost spark system. It is used on many motorcycles. There are two winding in the coil. One to each cylinder. Both fire at the same time. In motorcycles it does away with a distributor. You cannot do this with one coil with a wire going to each plug. Change the module........ken

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Guest ekvh

Ronnie was right, and I am sure I misled some of you. The plug wire was all burned and corroded inside the boot near the plug and back into the wire for a few inches. They are still covered under warranty so I will get new wires tomorrow. I didn't think there was juice at the coil because when I removed the boot at each coil top, the spark would arc with a nice loud snap to the nearest point of ground, the mounting screw. When I pull the #6 boot it doesn't arc, but when I placed a screwdriver near the tower it did spark consistently, just not as intense. It makes me think the coil is weaker than the rest. The other side of the same coil arced down much stronger. Odd? I have had a drop in gas mileage and thought it was hesitating a bit more than usual. I am going to try to upgrade to Delco soon. I just need time and a junk yard.

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Guest ekvh

So each coil tower fires at the same time? You could reverse all of the individual coil wires and have the same performance? That seems to be a waste of juice.

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Not really wasted power. The total path for the spark involves both cylinders connected to the coil. One fires with the opposite polarity to the other. Try it with an inductive timing light and see. The two plugs on each coil will wear differently since the polarity is opposite and if using a single style platinum plug, half of the plugs will wear similar to a standard plug.

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Guest Bill_Boro

Has any body had experiance with an Accel, MSD, Mallory, or other high output coil module for a GM 3800 or are they just expensive over kill?

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Guest simplyconnected

At low rpm, they act like regular ignitions, although some models deliver two sparks. They really shine under high rpm's (like racing applications).

Conventional systems tend to drop off during high RPM's, or when battery voltage drops. Each system works a little differently, so do your homework. All of them are better than stock, generally speaking.

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Guest THEHKP7M13

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: simplyconnected</div><div class="ubbcode-body">At low rpm, they act like regular ignitions, although some models deliver two sparks. They really shine under high rpm's (like racing applications).

Conventional systems tend to drop off during high RPM's, or when battery voltage drops. Each system works a little differently, so do your homework. All of them are better than stock, generally speaking. </div></div>

Absolutley, but you do have to wiegh weather the cost is worth it or not.

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