2003 XC70 Misfire Question (New Plugs and Coils) Topic is solved

nicksorg · Post by **nicksorg** » 26 May 2017, 12:07

Hey guys.
Quick question. Car developed a rough idle and is misfiring. It's my kids' college car so I don't know exactly how long it's been like this. I pulled codes and it reported a misfire on cylinders 3,4,5. Last night I swapped the #1 and #5 plugs & coils, cleared the codes, and drove it today. Codes now show cylinder misfire on cylinders 1 and 2.

I'm going to throw new plugs in, but wondering about coils. Would 1 bad coil impact a bank of cylinders?
Thanks
Nick

JeffHicks · Post by **JeffHicks** » 26 May 2017, 17:37

Start with plugs, but be prepared to replace coils. Obviously you know that you can swap them to see if a misfire follows one coil from cylinder to cylinder.

You should probably also closely inspect all the wires running to the individual coils. If the plastic cracks on those - and it often does - it can cause some weird problems.

For what it's worth, I've had good luck pulling used coils off a couple cars at a local U-Pull-It Salvage Yard. $10 per coil, and the 4 I swapped into any of my cars are still working fine. It's a crap-shoot, but if you're wanting to save money that might be something to think about.

nicksorg · Post by **nicksorg** » 27 May 2017, 06:33

Thanks. I put in 5 new plugs and swapped out the coil and it is running better than ever.

Post by **FLXC90** » 27 May 2017, 12:59

Keep in mind with the coils, if one goes, then the set are likely nearing the end of their lives. If you can, change them all, especially for a geographically separated driver. Otherwise/also, educate the drivers to watch for the flashing CEL indicating misfires, so they can get codes read if need be.