XC 90 check Engine Light and Misfire

tballjohn · Post by **tballjohn** » 20 Dec 2008, 17:10

Driving home in my '03 XC 90 T-6 this afternoon and it started misfiring, had a loss of power, and a slight shaking in the engine compartment. Then low-and-behold the check engine light came on. When I accelerated, if even flashed.

I stopped in at my local AutoZone and they read the following code (confirmed by my local independent whom I barely caught still open):
P0302 - cylinder #2 misfire detected.

My independent said culprits could be injector or spark plug/wire. Since it was flashing, he thought it was in the ignition system (plugs/wires maybe). I picked up some plugs (no wires in stock) and will start with them.

Any similar experiences (and where the heck are the plugs hiding...). Thanks.

Post by **MadeInJapan** » 20 Dec 2008, 19:07

Not on an XC but with my S70, yes...and it was plugs. Make sure and gap them correctly...this would be in your owner's manual. Also, my experience has been to avoid Bosch Platinum plugs...actually, regular copper core work very well- just change them out at 30K miles (Volvo plugs are good until about 50K miles unless you're doing some heavy duty towing or driving excessive mt. roads, etc.). If that doesn't get it then you might be in for new wires too. On 70 series, the OEM cables are made by bougicord- most others (including Bosch) will cause problems. www.fcpgroton.com sells the right ignition wires for your car...right now, "frosty" at checkout will give you a 10% discount. Good luck and let us know how things work out.

Post by **billofdurham** » 22 Dec 2008, 12:06

and where the heck are the plugs hiding

There is a cover on top of the engine. Remove this to expose the ignition coils which sit on top of the plugs.

Bill.

tballjohn · Post by **tballjohn** » 26 Dec 2008, 15:18

Thanks for the reply's ( did take apart the turbo hoses and the plastic cover to uncover the plugs and coils). Changed the #2 coil and all the plugs. Ran ok for a bit (maybe 30 minutes or so). Then started running rough again. Check engine light came back on. Now Code indicates a #3 cylinder misfire. Do the coils typically "go bad" around the same time, and is this typical around 100K miles? I have found the coils for about $50/each on-line. Although I exposed them, did not change the first one. Any "tricks" in removing/replacing the coils? Being a "coil", does it need to be dis-charged? Thanks again.

Post by **MadeInJapan** » 26 Dec 2008, 17:16

They just unscrew and you replace them, but it is rare that they all start to go right after another. Best to check the plugs first...make sure to avoid Platinum plugs (our cars don't like them) and also check the plug gap...your owner's manual will have the correct gap for them. If all of this checks out, then I guess you're in for the coils....but what you mention is something I really haven't heard happening much.

tballjohn · Post by **tballjohn** » 07 Jan 2009, 15:06

Well, brought it back to my independent and they have had it for a couple of days. They checked MAF and remaining coils. All tested ok, even tried new ones, but there was no difference. A tech bulletin apparently says to check engine compression (I guess a few of these have been popping up) to see if valves may be sticking. Low and behold, compression is around 120, except for #4, which is about 60 or so. They mentioned a bent "slide" and removal of heads to replace them is worst case scenario. Waiting to hear back on possibilities, costs, etc.

Any thoughts/ideas/alternatives? Thanks a ton!

Post by **MadeInJapan** » 07 Jan 2009, 16:07

Get them to check the cam position sensor too...
This can cause misfire codes, is fairly easy to replace and doesn't cost very much- doesn't always come up as THE code.

tballjohn · Post by **tballjohn** » 07 Jan 2009, 19:08

I will do that first thing in the morning when he calls. Thanks!

tballjohn · Post by **tballjohn** » 13 Jan 2009, 23:40

cam sensor seemed to be ok. They lubed the valve per the tech memo and drove around at high RPM's to burn it off. Put it back together, did another compression test. All cylinders read about 120. He said it could be the fix, or simply temporary. Running great now, but we'll see how long it lasts. Might be trading in on a newer one this weekend...Thanks for all the help!

Adarchie · Post by **Adarchie** » 20 May 2019, 15:23

billofdurham wrote: ↑22 Dec 2008, 12:06
and where the heck are the plugs hiding
There is a cover on top of the engine. Remove this to expose the ignition coils which sit on top of the plugs.

Bill.

Ok we are trying to change the spark plug to the 2nd cylinder. Standing at the hood is is the 2nd spark plug going left to right or another one?