2006 XC70 Bad gas or start ordering parts PO30X codes

JimG63 · Post by **JimG63** » 11 Nov 2015, 05:06

Shortly after putting gas in the car the other day, it started throwing codes along with a flashing CEL and sometimes it will stay on.

Initial codes were PO442 which is usually the gas cap not tight, PO300 random multiple cylinder misfires, and PO303 cylinder 3 misfire.

I put some fuel treatment in the tank, hoping that it's a fuel problem, but the car is still throwing the 300 code, the 303 code, and now also the 301 code.

My research on this and other forums suggests changing the coils and plugs.What other issues can cause this? clogged injectors? Are those a difficult change? Fuel filter?

Car has about 168k miles on it and I bought it with 144k and have no history on maintenance.

Post by **abscate** » 11 Nov 2015, 06:39

Nothing to do with gas if it's one cylinder. Bad gas is usually like food poisoning....wrong diagnosis

Try swapping coil 3 for coil 1 and seeing if the codes move. If not , pull the plug, inspect , and check compression on cylinder 3

JimG63 · Post by **JimG63** » 12 Nov 2015, 09:35

Update: Took advantage of NAPA's bucket sale (20% off everything that you can fit in the bucket) and got the Eichlen ignition coils for $46 apiece, saved $79 bucks off my entire order.

Drizzly yucky day here in CT and I have no garage, so I set up my pop up canopy, took my time and replaced all of the plugs and ignition coils. As you can see in the pic the plugs were well overdue for replacement. I was getting misfire codes on cylinders 1 & 3 as I mentioned in my original post. All of the plugs as I removed them gave resistance then "broke" loose, except #3, it just unscrewed. You can see wet oil residue on the #3 plug, whereas all the others have dry threads.

Easy job, about 2 hours start to finish including doing a back flush on my heater core. Still can't get the air "hot" though, only warmer

Engine is running FANTASTIC now.

Post by **abscate** » 12 Nov 2015, 15:42

I'm guessing those gaps are 040-050, almost twice spec

Post by **regent** » 12 Nov 2015, 16:34

Oh yes... Excessive gaps = excessively high voltage in the secondary, which kills the coils in a short order.

Did you massage the coolant hose to the T-stat housing; this may help bleed the air trapped in the system. I hope the T-stat is correctly positioned with the bleed orifice facing forward

Post by **IdahoBob** » 13 Dec 2015, 22:51

I just had the same sequence of events with my '06 XC70, in the last hour of a 300+ mile drive home after T-Giving:
> Filled up late in the evening, Sunday of a holiday weekend, snowing (moisture, bottom of the station's tank, and other concerns)
> Within 15 miles started have misfires when pulling a grade or accelerating.
> I travel with a code checker (690K miles between the three Volvos in the drive...always have tools and a code checker). The car is showing the 300 code for a non-specific misfire, and then 302, 304 and 305 for misfires in those cylinders.

When I get home I add injector cleaner and top off with pure (no alcohol) gasoline. My theory is that the alcohol gas "driers" are a waste, given that most gas already has ethanol in it. I was hoping the injector cleaner would dissolve any particulate that was clogging injectors, and that the pure gas would just take some load off the engine.

The raggedy misfires continued for the next couple of days of commuting, then settle into cylinder 4.

I swapped 4's coil with 3, and confirmed with the code checker that the coil was bad.

I also had the one wet plug, and the plugs needed gapping; so I replaced them all, after setting them to the proper gap.

I'd recently replaced one of the other coils, so this time got four more new ones; so that I now have 5 new ones, as my wife drives this care most of the time. I saved the used-working ones for spares.

IPD has the best price on plugs right now ($2 each) and Amazon has the Bosch coils for $43-ish.

I'm interested in others' thoughts. In my time working on my cars (40+ years) I've seen events where one stressor takes out other parts. I think what happened in my case, and in Regent's situation, is that bad gas made the aged coils work harder to fire all of those excessive-gap spark plugs, and 'pop' went the one coil. The gas was the original problem, which led to the coil blowing through overwork.

Happy Motoring!

Post by **vtl** » 14 Dec 2015, 04:41

IdahoBob wrote:My theory is that the alcohol gas "driers" are a waste, given that most gas already has ethanol in it.

Gas also has solvents in it, so I'm quite convinced that those additives and cleaners became an automotive kind of herbalife over past 20 years.

Post by **abscate** » 14 Dec 2015, 23:45

The gas fill was probably coincidental to the ignition failure rather than casual. Hard to prove of course. Ethanol gas does suck up water better than non-ethanol gas of course, so there is less need for dry gas ( methanol or isopropyl alcohol)

Glad you got her running again!