Strange spark issue, need advice

[M@]

So, I'm in the process of getting the regal roadworthy again, and the thing has an odd misfire issue.

I've tracked it down to the #4 cylinder, and know it's getting fuel, but the thing seems to only be sending a very weak spark to that cylinder. If I remove the wire from any other coil terminal, the spark will jump around wildly, grounding out to any metal within a few inches. The #4 terminal does not do this. It will only ground if something is brought within a 1/16 of an inch or so from it, i.e. that cylinder is only getting a very weak spark.

Is that indicative of a bad coilpack, an ICM issue, or something else? I think the only problems I've never had to troubleshoot on these things are spark related/ignition problems. Had to happen sometime I suppose.

So, thoughts? What to replace first?
I need to get the thing drivable ASAP, because my neighbor backed into the thing, and I need to get to a few body shops for estimates, to get the ball rolling on fixing the bastard.

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[Eagle]

My vote is coil pack, if you've already tested out the wire.

 

[SRT41320]

first swap the plug and wire with another cylinder and see if it follows the swapped parts or stays @ cyl 4....if it stays then its a coilpack or injector (prolly coil pack)

 

[Eagle]

That's what I said less the injector part...

CPs die on these POS's all the time now. They're getting old.

 

[SRT41320]

dont squint at me unless your ready to back it up!

 

[Eagle]

:rollpicard:

Lets do dis.

 

[M@]

Like I said, ANY other coilpack terminal, if you remove the wire while the car is running, spark will jump around like crazy, grounding to anything nearby, exception being the #4 terminal.

It just seems odd that one side of the coilpack is fine, and the other side is really, really weak. It just blows that a coilpack is one of maybe 2 spare parts I DON'T have from these things.

I did swap the plug, and the wire with others, problem persists on cyl 4. I'm 100% certain that the spark from that coil terminal is much, much weaker than any other terminal, so if that's indicative of a bad coilpack, I suppose that's the issue.

This doesn't sound like ICM to anyone correct? That would be a considerably larger pain in my ass....

 

[Eagle]

I vote CP for sure now.

 

[M@]

win...now to find someone with a spare, Beuller?

 

[Eagle]

I got nuttin

 

[smug]

I just got rid of my coil packs
I am offically out of 3800 parts

 

[M@]

dirty whore

 

[Sinister Drag Designs]

We have a few sets in stock if needed and ICMs. Try taking some 80 grit sandpaper to the top of the posts. This has helped or fixed more coil pack issues then I can think of.
And yes, one of the two posts on the CP can go bad.

 

[bikrboy128]

ive got a few laying around.
have you tried switching coils around on the ICM?

 

[M@]

Terminals on both the ICM and coilpack cleaned, they were most certainly corroded, but there was no effect.

Swapped packs, and it did indeed move with the pack, so that pack is off the car.
I think KJ might have one he can bring me this week, but if I do end up needing one, I'll let one of you fellas know. I need this bugger running by next week to get it to the body shop (argh).

 

[bikrboy128]

where are you at now?
if you're too far from me i can ship you one free, just pay for shipping.
lmk

 

[Ron Vogel]

Try replacing the spark plug on the other side of the coil pack...more than likely it's shorting. It's a waste spark remember...

 

[Yaj Yak]

illl bring the pack. got one fo sho

 

[M@]

Try replacing the spark plug on the other side of the coil pack...more than likely it's shorting. It's a waste spark remember...

Would that not result in a misfire on the opposite cylinder as well?

The only miss is on cyl 4 (top terminal of bottom coilpack), and the spark coming from that side of the coilpack is weak. When nothing was changed except the location of the coilpack (swapped position with the middle pack), the misfire moved with the offending pack, and again, exhibited a weak spark when the wire was removed from the plug, and allowed to ground on the frame. That seems like it could only be one bad coilpack, no?

To bikrboy's question, I'm back in Springfield currently...

 

[Ron Vogel]

You'd think it would effect both, but that's not always the case. It's worth a quick look though. Electronics don't always behave like their supposed to. The phase of the spark is flipped from positive to neg, and back when firing opposing cylinders, and using the plugs as a ground. I've seen bad/shorted grounds do some pretty weird things that plain didn't make sense.

 

[Turbocharged400sbc]

the current flow through the coil is the same, it doesnt alternate polarity, one coil terminal is always ~7kv less than the other as it is a negative firing terminal, one bank will have more worn center electrodes the other will have more wear/metal transfer from the ground strap.

good tip for those that want to eek out some extra miles on their plugs, swap coil wires to equalize plugwear....dont do this with just one cylinder, as ive seen issues with mixing coil/plug polarities (though that was the ford edis stuff)

 

[TommyGloves]

the current flow through the coil is the same, it doesnt alternate polarity, one coil terminal is always ~7kv less than the other as it is a negative firing terminal, one bank will have more worn center electrodes the other will have more wear/metal transfer from the ground strap.

good tip for those that want to eek out some extra miles on their plugs, swap coil wires to equalize plugwear....dont do this with just one cylinder, as ive seen issues with mixing coil/plug polarities (though that was the ford edis stuff)

Dude...how the f*ck do you know all this stuff?

 

[Eagle]

hillbilly through and through.

 

[ldyzluvdis06]

To bikrboy's question, I'm back in Springfield currently...

bad ass! if i get the turbo'd junk to start and fix the gas leak we will have to meet for a beer or something so u can jump in for a ride.

 

[M@]

bad ass! if i get the turbo'd junk to start and fix the gas leak we will have to meet for a beer or something so u can jump in for a ride.

sure man, just give me a shout sometime.