2000 S80 plugs burnt

[asummers]

From an earlier post I got some advice that if you look at your plugs and you see some that are black, instead of whitish, then the coil needs to be replaced at the black plugs. This also goes in hand with the code that told me I had Multiple Misfires. Take a look at the picture and I see the plugs in the 1, 2, and 3 cylinder location as needing new coils. Anyone out there have experience at this to let me know if it would be the coils? I am planning on ordering three coils and a set of Volvo plugs. Hopefully that will remedy the rough running at idle condition.

[boosted5cyl]

Hmm I wouldnt assume coils yet. Plug fouling can happen for a variety of reasons. What interesting is that the three fouled plugs are on the same fuel loop. Heat the tip of the plugs up with a blowtorch to clean them, forget abrasives or wire brushes. Or at <$2 each just replace them and gap them to .28" and swap coils 123 with 456. Clear the ECU codes too, drive a week or so and check the plugs again. If 123 endup fouled again then you know your problem is probably not coils.

What you are seeing on 123 is not burning, in fact its quite the opposite. Its carbon deposits from the plug not being kept in its correct heat range where it is self cleaning. There can be many causes for this, misfire is just one of them. Yes, its possible that there are three faulty coils, but I would swap them around before dropping $150+, especially given they are in the same fuel loop together.

The other thing is that the misfire would need to be REALLY, REALLY bad to foul the plugs like that. Does it misfire all the time, or just when it driven hard?

Another thing is that ignition problems\weaknesses "typically" manifest themselves at peak cylinder pressure, ie peak torque rather than idel . Unless the coil is totally dead, in which case your plugs would be very wet as well as black as there would be no fuel getting burned at all. This was the case in my car, I had one totally dead (as opposed to weak) coil.

/edit 2.9 is non turbo right? I guess you might want to double check the plug gap for the non-turbo.

/edit #2 Sorry im at work and kind of switching back and forth. I saw you said its got a rough idle. Before you buy coils, buy a set of cheap copper plugs at your local auto store, pop em in and see what happens. Those plugs are fouled bad enough to cause a rough idle. Question is why they got fouled, but if it idles OK for a while with new plugs then you know the coils are probably fine. Have you pulled the codes from the ECU?

[asummers]

Thanks so much for the advice!
I like the idea of putting in the cheap set of plugs and moving the coils
to the 4, 5 ,6 position.
I will mark the coils with a paint pen so I can keep track of them, reset
the computer and see what happens.
I also think I have a oxygen sensor that needs replacing. The "system too
lean bank 2" code. Do you happen to know if bank 2 is on the 4,5,6
cylinder side, or on the 1,2,3 cylinder side?

It seems to run well at highway speeds, and only misses and runs rough
when at idle, in gear or in park.

I did pull the codes, this is what it told me...
P0300
Random/Multiple Cylinder Misfire Detected
P1153
Manufacturer Specific DTC See Service Manual
P0174
System Too Lean Bank 2
P1181
Manufacturer Specific DTC See Service Manual
P1171
Manufacturer Specific DTC See Service Manual

[JDS60R]

Classic oxy sensor failure.
If this is a 2.9 with an 02 (oxygen) sensor in each of the exhasut manifolds (handles 3 cylinders each) - then the oxy sensors have gone bad. 1,2 and 3 not only have carbon fouling but it looks like ( very hard to tell from pic) that it has some detonation damage as well.

Replace your oxy sensors, clean the Maf (With MAF cleaner when cold only) and reset the adaptives on the computer.

best to do all of the oxy sensors at once. Use Matthews link and buy direct fit Bosch replacements.

Its possible that an intake leak exists closer to cylinder 1 but a bad 02 is more common.

[asummers]

Last night I put a new set of plugs in, I would have to do that anyway. And I moved the three coils to the other three cylinders. We will see what happens. I do know it needs one of the oxygen sensors replaced, so I will probably need to go ahead and do that too. From the way the plugs looked it is the oxygen sensor on the driver's side.

[JDS60R]

Great to hear you are moving forward.
Keep in mind the service life of the oxy sensors is only 100K miles. (accuracy falls off dramatically)

Using Amazon,(and Matt's link) we have been getting them in the $80 range for direct fit Bosch. If you are over 100K I would change them all. The performance ,gas savings and reduction in engine deposits easily makes up for the cost.

[asummers]

With the new plugs it has not repeated the multiple misfire code yet. And I have also took my ETM off and cleaned it per the directions of the ETM cleaning post on this site. And it runs so much better now! After clearing the codes the only code my code reader is reporting now is "P1152 Manufacturer Specific DTC See Service Manual". But, I got a list of codes from V70R.com and it listed the P1152 as Front Heated Oxygen Sensor Bank 2 Signal too high. So, the next thing to replace seems to be the front oxygen sensors.

[boosted5cyl]

After clearing the codes the only code my code reader is reporting now is "P1152 Manufacturer Specific DTC See Service Manual". But, I got a list of codes from V70R.com and it listed the P1152 as Front Heated Oxygen Sensor Bank 2 Signal too high. So, the next thing to replace seems to be the front oxygen sensors.

I think you might need to replace both front O2's though. I'm pretty sure cyls 1-3 are bank 1 and 4-6 are bank 2, which somewhat contradicts the code you are getting. That said, faulty parts dont always throw a code. Maybe replace bank 2 sensor first (the one throwing a code), drive for a while and check the plugs in cyls 1-3 after a couple of weeks. Or if you just want to be done with it, replace both pre-cat O2's