Miss/Stumble/Surge - Coils?

[jdj2]

I'm chasing an idle miss/stumble, and getting pretty frustrated.

The problem is most pronounced at idle, but does sometimes carry up into the higher RPM's. It feels like a hard miss, but then the engine starts surging up and down as if trying to compensate.

ETM was recently replaced, and I've cleaned the MAF and the boost pressure sensor and replaced the plugs.

The thing is, I can't get this thing to throw a fault code. I even went so far as to disconnect a coil tonight to see if it would set a mis-fire code, and nothing.

I suspect Volvo "dumbed up" the diagnostics during the ETM replacement to avoid comebacks, but this is pretty ridiculous.

Without error codes, I feel like I'm chasing my tail a bit. Any input or advice would be appreciated.

Another item of note - All 5 coils have cracks in the plastic on the side opposite the connection. Is this normal, or am I looking at the obvious problem? I hate to spend $300 bucks on a hunch.

2001 V70XC
86,250 miles

[Bruce McClure]

I am having a similar problem with my +100,000 mile V70XC.
Have you solved your problem?

[MoeB]

No, cracks in the coils are not normal and that may be your problem. I just recently posted about this in another thread called "Check Engine Light-FYI." The cracks allow spark to leak out and can cause missing and rough idling, among other things.

I don't think you will get a code for the coil itself since the ECM still sees juice going to the coil, but it can't tell that it's going to the head instead of the plug. However, you may eventually get a code for the catalytic converter once enough unburned fuel gets in there and causes the cat sensors to read out of range. If you run with bad coils long enough, you'll eventually ruin the cat, or worse.

That may not be your only problem, but it's still a problem. I'd get new coils pronto if it were mine. I had to change mine at around 90k miles and I see your near that on your car. Probably not coincidence.

[uscgc70]

I too had to change my coils at 100,000 miles. they are very easy to change yourself.

[jdj2]

Guys thanks for the responses.

An update on my problem. Finally took the car to the dealer. I was stunned that a car could run this poorly and not throw a code, but I suspect that the ETM "software" fix really gutted the fault detection in the software.

Anyway, in order, here is what has been done:

1) Replaced the MAF. This corrected 96% of the issues I was having. When cold, I might still get a slight stumble, but the difference was radical, so obviously, the MAF was a problem.

2) When my MIL light came on again, I went back. They "re-programmed" the ETM software (ETM was recently replaced).

I've since had the MIL light come on once more, but I have not been back.

I pointed out the cracked coils to the service manager, and he didn't seem to concerned about it. I'll likely replace them anyway, but $300 bucks hurts a bit.

Anyone know a good place for coil deals?

[04v70]

Anyone have an update on this?

[ovlovpumpkin]

Anyone have an update on this?

i'm working on the same issue currently. have been having some of the same issues that i've read in this thread with the rough idle at low rpm's, cel on and flashing then pausing, etc. i just changed out the spark plugs with volvo plugs on saturday but the problem persists. i have about 98,000 miles and have never changed out the coils so i ordered some new coils from ipd. i'll have to take some pictures and post an update on here when i install them. i'd love an update on anyone else's experiences as well.

[04v70]

OK, my car went to VIDA equipped Volvo indy this morning. I will report back when I know more.