So I purchased my 09 CTS4 w/ DI Premium not so long ago from a major dealership for a steal after negotiation and since a good friend worked there. The first owner of the car kept up was early with all the maintenance as reported by CarFax but the second owner (who didn't have it long anyways) only did maintenance a couple of times within the year or so that he owned it. I love the car and I can’t wait to perfect its look and performance! Anyways, after the first 50 miles of driving it, I felt it “stutter” at 2100 rpms. Then the CEL began to flash and remained on.
**At this point you can read on or skip to the next set of asterisks.
From idle to acceleration I felt a loss of power at 2000-2500rpms and it would feel fine once I reached 3000rpms and remained at a steady speed. If I slowed down for any reason, it would take a while for the drive to be comfortable again as the car would stutter. The only way to force it to stop was to floor the accelerator until it reached at least 3000rpms. :crying2:
During long highway drives, I didn’t feel it often. Within a distance of 100 miles I would probably feel this about 5 times on average because I was behind a slower car, approaching a speed trap, let my foot off the pedal, etc. I normally cruise anywhere between 75mph-80mph and have redlined a few times without feeling any problems. But in-town drives sucked since it was stop/go.
** I drove like that for a few weeks. I never had the time to fix it but I was confident it was a misfire in the second cylinder. I wanted to make sure there were no other cylinders with the same problem so I took it to Autozone and had them check it. They confirmed that there was a problem in Cylinder #2: could be a bad spark plug or ignition coil.
So I saw this as an opportunity to finally get under the hood myself.
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I went ahead and decided to purchase 6 NGK Iridium IX spark plugs + one extra as a spare because you never know even though they are estimated to last 50,000 miles. I know there are better NGK plugs, however, I wanted to be safe but still use high performance plugs. (Is it risky to use the NGK Laser Platinum plugs? Is it safe for the car?)
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Changing the plugs was easy as the intake manifold for the Second Generation is smaller than the ones in Gen 1 (They are smaller right?). The only thing I had to remove was my Strut Tower Brace. I watched a video on YouTube that showed someone having to tilt back the intake manifold on an ’07 but once I was inside and realized I could easily remove the ignition coils with a 10mm socket for 5 of them and an adjustable wrench for one of the more tucked away ones.
Long story short, replacing all 6 took no more than 1 hour. I disconnected the battery in the trunk for about 30 seconds to clear the CEL. I drove the car for 2 hours immediately after at an average speed of 78mph and there were no issues! Fortunately, I didn't need to even change an ignition coil. I read somewhere in this forum that if the CEL flashed and remained on afterwards that it was definitely an ignition coil. In my case, this wasn't true.
*** More about the trip and performance below or skip to the next set of asterisks:
After closing my hood and living only 1 minute from the interstate, I took the car on a 140 road trip immediately. I slowed down for nothing using Waze. I have brand new tires so even though it rained to the point where I couldn't see more than 3 car lengths ahead I still remained at 80mph.
I did several tests to ensure all problems were fixed;
I no longer had any stutters from 0-60 after leaving the ramp onto the interstate. I floored it, of course. The car sounded amazing!
Once I was able to cruise at 80mph the car remained at a comfortable 2000rpms and it took no effort to hit 100mph.
When I hit the heavy rain, there were no cars nearby so I did a hard brake from 80mph to 40mph and immediately floored it to 100mph. No issues at all…
Do I even need to describe how it felt switching to Manual Transmission?
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I felt like I got my balls returned to me after driving with a misfire for so long. The 09 CTS4 w/ DI has about 305 horsepower but with the bad cylinder it definitely felt like 50 of my horses had bad hooves, haha..
So far, I’ve driven about 200 miles (170 +/- Highway and 30 +/- In Town) after the install and now have an average MPGs of 19.5 MPGs after having about 17.5 MPGs with the bad spark plug in Cylinder #2.
*** If anyone would like a detailed overview of the spark plug replacement, feel free to request it below. I’d be glad to. I’ll also include pictures of the process.
Also, has anyone else used the NGK Iridium IX plugs in their car? For how long have you had them and how does it feel with them? Any issues?
All comments are welcome. I’m new here and would love to hear more about our awesome CTS Gen 2s! :cheers:
**At this point you can read on or skip to the next set of asterisks.
From idle to acceleration I felt a loss of power at 2000-2500rpms and it would feel fine once I reached 3000rpms and remained at a steady speed. If I slowed down for any reason, it would take a while for the drive to be comfortable again as the car would stutter. The only way to force it to stop was to floor the accelerator until it reached at least 3000rpms. :crying2:
During long highway drives, I didn’t feel it often. Within a distance of 100 miles I would probably feel this about 5 times on average because I was behind a slower car, approaching a speed trap, let my foot off the pedal, etc. I normally cruise anywhere between 75mph-80mph and have redlined a few times without feeling any problems. But in-town drives sucked since it was stop/go.
** I drove like that for a few weeks. I never had the time to fix it but I was confident it was a misfire in the second cylinder. I wanted to make sure there were no other cylinders with the same problem so I took it to Autozone and had them check it. They confirmed that there was a problem in Cylinder #2: could be a bad spark plug or ignition coil.
So I saw this as an opportunity to finally get under the hood myself.
I went ahead and decided to purchase 6 NGK Iridium IX spark plugs + one extra as a spare because you never know even though they are estimated to last 50,000 miles. I know there are better NGK plugs, however, I wanted to be safe but still use high performance plugs. (Is it risky to use the NGK Laser Platinum plugs? Is it safe for the car?)
Changing the plugs was easy as the intake manifold for the Second Generation is smaller than the ones in Gen 1 (They are smaller right?). The only thing I had to remove was my Strut Tower Brace. I watched a video on YouTube that showed someone having to tilt back the intake manifold on an ’07 but once I was inside and realized I could easily remove the ignition coils with a 10mm socket for 5 of them and an adjustable wrench for one of the more tucked away ones.
Long story short, replacing all 6 took no more than 1 hour. I disconnected the battery in the trunk for about 30 seconds to clear the CEL. I drove the car for 2 hours immediately after at an average speed of 78mph and there were no issues! Fortunately, I didn't need to even change an ignition coil. I read somewhere in this forum that if the CEL flashed and remained on afterwards that it was definitely an ignition coil. In my case, this wasn't true.
*** More about the trip and performance below or skip to the next set of asterisks:
After closing my hood and living only 1 minute from the interstate, I took the car on a 140 road trip immediately. I slowed down for nothing using Waze. I have brand new tires so even though it rained to the point where I couldn't see more than 3 car lengths ahead I still remained at 80mph.
I did several tests to ensure all problems were fixed;
I no longer had any stutters from 0-60 after leaving the ramp onto the interstate. I floored it, of course. The car sounded amazing!
Once I was able to cruise at 80mph the car remained at a comfortable 2000rpms and it took no effort to hit 100mph.
When I hit the heavy rain, there were no cars nearby so I did a hard brake from 80mph to 40mph and immediately floored it to 100mph. No issues at all…
Do I even need to describe how it felt switching to Manual Transmission?
I felt like I got my balls returned to me after driving with a misfire for so long. The 09 CTS4 w/ DI has about 305 horsepower but with the bad cylinder it definitely felt like 50 of my horses had bad hooves, haha..
So far, I’ve driven about 200 miles (170 +/- Highway and 30 +/- In Town) after the install and now have an average MPGs of 19.5 MPGs after having about 17.5 MPGs with the bad spark plug in Cylinder #2.
*** If anyone would like a detailed overview of the spark plug replacement, feel free to request it below. I’d be glad to. I’ll also include pictures of the process.
Also, has anyone else used the NGK Iridium IX plugs in their car? For how long have you had them and how does it feel with them? Any issues?
All comments are welcome. I’m new here and would love to hear more about our awesome CTS Gen 2s! :cheers:
