1998 V70 Spark plugs look dirty, but are they normal?

[cn90]

You will get 100K out of Iridium plug.
So $5 for Volvo plug will get you to 30K-40K (it is probably overpriced copper anyway) and $7 for Iridium that gets you to 100K.
Now you can say the Volvo plug is overpriced.

Virtually all new cars now leave the showroom with Iridium plugs, and there is a reason for that (good for marketing but also good for consistent fuel economy).

My 2005 XC90 2.5T runs on Iridium plugs, and the engine idles very smoothly, acceleration is excellent and no engine hiccups at all.

[RussB]

I'm not going to mention which plugs I run in what, because it's irrelevant to this thread. We want to diagnose the black soot and misfire on cyl 4 the OP is getting. I've asked some pertinent questions which will help us get to the cause...still awaiting a reply from the OP.

[misha]

...They're Volvo plugs, no question about that, but I thought there was a general agreement that the multi electrode plugs are not these engines' favorites...

Oem Volvo plugs can be with single or triple prong.
Advice from other owner's experience was to avoid iridium or platinum plugs for these cars.
I personally use oem Volvo triple prong spark plugs for non turbo models from the day i bought the car.They have 100k km service life and i never used anything else.I bought the car back in 2000.

That black residue on those spark plugs could be from frequent short city driving and possibillity that engine runs a little richer than it should.
Is check engine light on?

[dosbricks]

Good one Matt! But isn't Darth supposed to be the turbo guy?

[dosbricks]

Okay, the OP's car is NA. Everyone on board with that?

My personal experience is--wait for it--33 combined years of running the plugs which Volvo designed for their 2.4 NA engines, except for an experiment with Bosch four prong platinum which misfired and were rubbish after 20k miles (not cheap either). One other time I tried NGK single electrode which performed poorly.

The only thing I'm learning from this thread is that I could have probably got more life out of my plugs with less frequent changes.

Now again, what was it the OP asked about??

[Sommerfeldt]

...They're Volvo plugs, no question about that, but I thought there was a general agreement that the multi electrode plugs are not these engines' favorites...

Oem Volvo plugs can be with single or triple prong.

That's what I said, wasn't it?
Anyway, I used single "ground" plugs on my '95 850 base, and never had a whisper of an issue with them. Come to think of it, I've never had an issue with Volvo OEM single "ground" plugs on any of my Volvos.

OP says there's misfire. That, coupled with the dirty plugs (again, I've never seen anything like it when the plugs are 2 months old) certainly points to ignition parts, though the plugs may or may not be innocent.

- S

[mecheng]

Iridium and platinum plugs will definitely laser longer than copper electrode plugs, BUT copper is a much better electrical conductor so it may put more stress on the coil. I have champion plugs as per the Volvo manual. Never ran champions before but the engine is as smooth as silk with them

[cn90]

That is not true at all.
Do a little search on Iridium plug and you will see.
The core of Iridium plug is still copper.
There is more to "copper" "platinum" or "Iridium" names.

NGK has very good reputation. I have 2 BMWs and 2 Volvos, they all run on NGK Iridium, zero issues.
As others said...make sure the cap/rotor/bougicord are good too.

[abscate]

on advice of this thread I went out and bought 5 Iridiums but they won't fit into the spark plug holes,,,any advice?

[cn90]

abscate,

What is the NKG Number?
Did you buy the NGK I mentioned earlier?