myamymy

Makes sense. Thanks a lot. I will get the tool to read the codes.

Dom991.1

I changed the plugs for my 4 yr/40k mile service and and NO issues removing the coils from the plugs - could there have been another issues as to why yours were so difficult to remove? I had the cats off anyway (I replaced them with 200 cell units) so that made the job easier, I bet. I simply unscrewed the bolt that held them to valve cover, unplugged them, and rotated slightly clockwise & counter clockwise while pulling outward to release them.

Forgot to say - obviously I removed the O2 sensors but tried to be very careful with wires. THOSE were tough to loosen but eventually came free. My engine was also a 3.4 (2015)

Last thing - I may have a spare set of O2 sensors (all four) with <1k on them. If you need some PM me & we can work through details.

myamymy

Thanks for your input.

My coils came out easily but the rubber piece which is attached to the tip of the coil got stuck inside the tunnel. Couple of other members had the same issue.

If I need O2 sensors I will PM you.

Regards

sessionstu

Have you tried clearing the error codes? Durametric works great. Every time I do something on my car I get an error message. After I clear the error it never comes back. Just a thought.

sdl2112

For those who have changed plugs on a 991.1, is it necessary to remove the O2 sensor if you have proper extensions and a universal joint adapter?

Thx

myamymy

You don't have to but makes it much easier to reach to #1 and #4 plgs. It takes only a few seconds to uninstall/install

myamymy

I used my friend's BlueDriver scanner tool. It is misfire #6 cylinder. I kind of knew it because the rubber piece of the coil was little damaged when I tried to remove it.

Sidvicious7

NA 3.8L 991.1 I used the proper extension and universal joint adapter to remove all six spark plugs without removing the O2 sensor. I found it easier to jack up the car and remove the rear tires. I also do a visual check on the gaps for each spark plug for assurance they were properly gapped by the manufacturer.

Spark Plug Replacement

991carreradriver

So now you have identified that it is a misfire. In my world that is usually a new engine but in yours - a different story. As I have stated before, change the coils when you change plugs. These devices will last 100k, except when you have to remove them earlier for a spark plug change - the rubber just does not hold up. For $230 change them out when you change plugs. I change out my coils every 2 years for just this reason. Who needs the grief or having thousands of dollars at risk for a track weekend missed. Just preventative Mx!

sdl2112

Ok thanks...now next question. What is the proper gap with these type plugs?

991carreradriver

They are pre-gapped, with four electric probes how does one even measure it?

Sidvicious7

I need to clarify what I previously meant by checking the gap on my spark plugs. For 2 or more point spark plugs the manufacturer [Bosch] recommends not to gap multi-point spark plugs because they’re not adjustable. The best you can do is visually inspect and compare the gaps from one plug to the next. Lastly take precautions when handling your plugs and ensure you do not drop them.

https://www.boschsparkplugs.net/lear...g-instructions

eagle1960

÷1 on " gapping" these plugs. I also had no difficulty removing, installing and torquing using readily available extensions and one universal and removing rear wheels . Don't make this harder than it needs to be.

Bry5on

A torn boot will allow the spark plug wire within it to arc to the head and cause a misfire. Check all of your boots closely for tears given your trouble. Sounds like a sure bet you found the source

sdl2112

I hadn’t heard of gapping these plugs either but I thought I read on here where someone installed plugs with the wrong gap and it noticeably ran bad. I’m changing mine this weekend and will cross check all plugs along with the originals taking into account any wear.