04 XC70 Multiple misfire

turbotim2 · Post by **turbotim2** » 17 Aug 2017, 15:39

04 XC70 195k miles
On the way home the other day and suddenly started skipping. Managed to get it home, pulled codes and got P0300, P0304, P0302. Switched some coils around to see if it was bad coils, made no difference but when I drive it and then clear codes it gives random cylinder misfires, could be 2 and 4 or 1 and 3, etc. in addition to the P0300 multiple misfire. I have checked wiring around the coils and injectors, there certainly isn't anything obvious. Any ideas on where to start?

turbotim2 · Post by **turbotim2** » 17 Aug 2017, 16:01

I should add that I have checked the plugs, nothing out of the ordinary there and replaced the cvvt solenoid.

Post by **abscate** » 17 Aug 2017, 18:19

Misfires are either plugs or coils 99.9% of the time.

Plugs will look good even when they are old and overgapped. Replace if they are over 30k miles old

Georgeandkira · Post by **Georgeandkira** » 18 Aug 2017, 07:07

Too bad you didn't note and clear the initial codes then resume driving the car to see if the same ones would return.

turbotim2 · Post by **turbotim2** » 18 Aug 2017, 07:20

I did, I get different ones each time. Seems odd that bad plugs or coils would be random like that.

Post by **jonesg** » 18 Aug 2017, 08:02

I'd say something else is triggering it.
I've had multiple coil code misfires that were unrelated to the coils.
I had previously checked fuses and put a couple back in the wrong slots. (in the engine bay).
Once I figgered that out the coils all cleared up.

Nother time I burned the fuse that runs the eBox cooling fan and that started setting codes all over the place with reduced engine performance warning. eBox contains the engine computer.

got Vida ?

turbotim2 · Post by **turbotim2** » 18 Aug 2017, 08:15

I haven't looked at any fuses. The only codes I have had are the misfire codes. Since it first happened the other day, it is constantly misfiring in one or more cylinders. There are no moments of it firing on all cylinders if you know what I mean.

turbotim2 · Post by **turbotim2** » 18 Aug 2017, 08:24

It doesn't seem right but could one bad coil knock out others?

Post by **jonesg** » 18 Aug 2017, 17:08

NO, a bad coil can be traced by swapping it and seeing of the misfire follows the coil.
Where is Maine are you? I'm moving to Island Falls in 10 days.
You need to get a vida scan done.

turbotim2 · Post by **turbotim2** » 18 Aug 2017, 17:19

Well it turns out one bad coil does cause multiple misfires. I figured it out, will write more later.