V70XC '99 Engine code P0303-cylinder 3 misfire

RichSad · Post by **RichSad** » 31 Aug 2010, 12:09

Driving to work this morning my check engine light started blinking. I pulled off the highway and checked the code. It was throwing a P0103 and the ever-present P0113. The P0113 is probably unrelated as this has been on for a while and there was no apparent malfunctions as a result. Been meaning to replace that IAT sensor.

The engine had seemed weak the last few days and now is definitely misfiring and idling rough with a significant loss of power. I am about to go do a manual inspection of the spark plug wires. I saw somewhere where it recommended switching cylinder 3's spark plug wire with a different cylinder and seeing if the code changes. This seems like a bad idea to me since the order that the cylinders fire is pretty important if I remember my gasoline engine theory. I get how it would be helpful to know if the problem is the wire or not but should I just switch plugs like that?

Any other advice for me? I realize this is probably a bad or corroded spark plug, bad wire, or something potentially more serious.

nwhitney · Post by **nwhitney** » 31 Aug 2010, 12:24

I thought the '99 V70XC had individual ignition coils instead of cap & wires. If you have individual ignition coils then you can swap coils to see if the misfire moves with out problems.

Post by **Pauloil** » 31 Aug 2010, 12:30

it's not hard to find the bad one, or in your case #3
pull off the aluminum cooling bar on the fuel rail
disconnect the wiring to the injector you think is bad if nothing change, that is it
if the motor runs worse try disconnecting a diff cylinder.

the coil packs are $45 at pcp

RichSad · Post by **RichSad** » 31 Aug 2010, 17:00

Thanks for the advice. I believe the '99 does have ignition coils. They are under the aluminum cooling bar so I haven't seen them first hand yet. My gas mileage dropped 5mph and the car has very little power.

I like the idea of swapping the ignition coils. Thanks to both of you for the advice.

Now I just need to find the right tools to take aluminum cooling bar off!

RichSad · Post by **RichSad** » 31 Aug 2010, 18:02

I just tried the advice above and seem to have narrowed it down to either the cylinder 3 ignition coil or ignition wire.

If I bought just a single ignition coil, how would I cut off the one that is there and install the new coil? I realize this is a pretty newbie question but I have never done that before.

Post by **Pauloil** » 31 Aug 2010, 19:55

a 10mm bolt holds it down and you have to loosen it to change plugs
romove and unplug old one, replace with new one
I carry one in the back of my wagon just in case
T30 bolts hold the cover on. might be a good time to change plugs

RichSad · Post by **RichSad** » 01 Sep 2010, 05:30

It looks like on mine there are 10mm bolts holding the aluminum cooling element down (although it is not clear to me that you actually have to remove the bolts to remove the portion that blocks access to the cylinders). When I was in there yesterday I didn't notice the 10mm bolt holding the ignition coil down, but your info is consistent with other info I've found.

A question on spark plugs: if I buy a replacement plug, do I have to set the gap to some specific gap size? In the tutorials I've found on this site about ignition coils/plugs, it doesn't mention setting the gap. I don't have tools to measure the gap but I could probably borrow some if necessary. Should I buy only the Bosch plugs?

Lastly, am I damaging the engine in any significant way driving on 4 cylinders for now? I need to get to and from work today (about 130 miles round trip). Gas mileage is down 5-7 mph but otherwise it does run.

nwhitney · Post by **nwhitney** » 01 Sep 2010, 09:14

You do need to make sure the gap is set correctly for your vehicle and the correct size should be listed in your owners manual. You can pick up a gap tool/sizer for $1 at an auto parts store. I would suggest changing all the plugs not just the one misfire.

RichSad · Post by **RichSad** » 01 Sep 2010, 14:57

I just realized that I don't really have evidence that supports that I need a new spark plug or ignition coil. When I plugged the cable for cylinder 2 into cylinder 3, cylinder 3 fired correctly and the error shifted to cylinder 2. That suggests that the plug and the ignition coil on cylinder 3 are fine and the problem is either the wire that goes to the coil or something further up the electrical chain. I guess what I need to research is how to replace that wiring as a first step. Glad I didn't go off and buy new ignition coils without thinking this through better!