do they just go bad altogether? Do they ever just go out under high load/high rpm?

I'm having ignition problems at high load/high rpm (obviously) and was just wondering. These are Electromotive Tec3 coils (full standalone) so...

8/29/2007 8:33:27 AM

depends on if the coil just totally dies or is weak.

8/29/2007 8:36:29 AM

if the coil is weak, or has a low voltage or a bad ground, at higher rpms, higher cylinder pressure, or load, it won't jump the plug gap, otherwise no, they dont intermittantly screw up.



have you actually checked your plugs/wires yet?

8/29/2007 8:38:25 AM

plugs are new (but blackened from intermittent spark). I assume I've driven the car enough to burn it off back to normal. Tried new wires with no luck.

the misfiring/stumbling was worse about a week ago and resulted in a rough idle. The two coils are a waste-spark setup with two towers from each coil. Strange thing was, one tower would spark consistently while the other one misses and/or sparks at half speed. I saw this with a biasic timing gun; each coil did this. Since then, I've gone through and rechecked/re-insulated some of the big positives (alt, starter, etc). The stumbling is gone except for at high load/rpm; I drove the car 45miles to and from work today. I haven't looked at it with a timing gun since getting the idle misfiring to go away.

I'll investigate the low voltage/bad ground idea a second time.

8/29/2007 8:46:43 AM

^ try grounding the coil bases directly to the engine block if they arent already, this will give you the shortest path since obviously the secondary grounds through the block also


what setup is it on? its possible there could be a pickup or computer problem

believe me i have been through this enough times on my old mustang with a full race msd system, optic dist, msd box that pulled 25 amps, 630 volts on the primary side, and 60,000 volt msd 10 coil, you name it, i had a problem with the damn thing, not to mention the primary or secondary wiring could kill you

8/29/2007 9:05:18 AM

I was pulling a trailer one time with a truck that had been running fine. When it was under load it would start popping and spitting back and wouldn't do it without the trailer. Everybody swore it wasn't the coil, but I replaced it anyway and it took care of the problem. I had a similar problem on a gas tractor once also.

8/29/2007 8:50:43 PM

are you positive its a coil and not a pickup problem?

8/30/2007 7:01:07 PM

I'm somewhat sure it's not a pickup problem. I tried replacing the sensor ('97 ford pickup magnetic crank sensor ) but it made no difference. Pickup problems will cause an output LED on the ecu to blink red at the time of occurrence; no such warning light at all.

Coil picks up +12v straight from battery (fused 9amp per guide). Wiring to the ECU harness looks perfectly fine.

I'm about to go take a multimeter to everything in a minute here...

9/1/2007 1:58:18 PM

All wires look good.

The pickup wiring is the only thing left I can think of. When I first got the setup, there was a shield wire going into the Electromotive sensor (sealed). Using the Ford sensor, there are only two prongs, positive (signal from sensor) and negative, so the shield is just tucked off to the side. I don't know anything about shielding wires; is there a way to use the shield wire in this setup/how to you shield a wire manually? The car has worked fine for a long time without the shield wire, but I'd like to go ahead and get that out of the way.

Looks like I'm pretty close to just shelling out for new coils

[Edited on September 1, 2007 at 3:56 PM. Reason : or.. where can you buy shielded wire? I've never been in the market for any]

9/1/2007 3:45:58 PM

just get some new coils already

9/1/2007 4:37:43 PM

anyone happen to know the resistivity across coil towers for GM coil GC411?

9/1/2007 4:44:32 PM