1999 V70XC Rough idle and engine stumbling is back! :(

[abscate]

I've run my coils with those small cracks ok, but the big ones running the length of the snout are probably bleeding off charge.

Your plugs don't look too bad to me.

[northernlights]

Wow. That would be something if 'leaky' coil packs are causing the appearance of other problems.

As kind of a hacker 'test/repair', wrap the hell out of the outside of the damaged coil packs with electrical tape and reinstall. That might be enough to mask the problem, so that you know it is the problem.

[warcraftjunkie]

I picked up 2 coil packs from the boneyard, one dated from 2009 and the other from 2004. Both showed no signs of cracking. In fact on the 2009, the rubber boot was very snug and didn't just slip off the coil like I was used to with my coils. Put them in my car and it made no difference to the idle quality of the car or the driving. Still stumbling and hesitating... and of course flat out stalling out. I took a couple videos, but since I'm at work I can't upload them from here.

I believe the coils need to be changed, but they are not the root of this problem... just overdue part replacement.

I know I have tested the B+ cable before, and I tested it again as well as the voltage drop between the +post to the main fuse box and it seems to be good, but I happened to put my hand down on the post and just about burned the crap out of it from the heat. It's not normal for it to be hot to the touch when the vehicle is running right? Heat build up is a sign of significant resistance I believe.... right?

[abscate]

Should not be too hot to touch, correct.

[northernlights]

I know I have tested the B+ cable before, and I tested it again as well as the voltage drop between the +post to the main fuse box and it seems to be good, but I happened to put my hand down on the post and just about burned the crap out of it from the heat. It's not normal for it to be hot to the touch when the vehicle is running right? Heat build up is a sign of significant resistance I believe.... right?

Something isn't right if the cable is hot. How much different is the battery from + post to - post vs + post to somewhere on the chassis? How about the voltage from the alternator with the same test, i.e. output to - post vs output to chassis?

I'd test everything to a good chassis ground point compared to battery - ...bad grounds can cause all kinds of problems.