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09' CTS4 3.6DI
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Discussion Starter #1
My engine is misfiring and is giving me a code for cylinder 5. I have yet to get it checked but under the assumption that it ends up being spark plugs or a coil, does anyone have brand recommendations when I go to buy them? Or should I not worry about the brand when it comes to coils and spark plugs? Thanks in advance!
 

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2011 CTS Coupe FE3, 2003 Thunderbird, Gone 2013 ATS, 02 Deville
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to help us help you, please list the mileage and recent work done.
Normally the plugs to use are AC Delco and name brang coils.
 

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08 STS 1SG HUD ACC F55 AWD, 08 STS 1SG Platinum HUD ACC F55 RWD
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Others may feel different but get the specific plugs called for by the factory. They must have really checked them out to then say change every 100000 miles. I also have seen horror stories of off brand coils. With that being said, I would change all spark plugs but move the #5 coil to another cylinder ( make it one that is easy to get to without removing the intake again). After you finish and start it again - if no miss = you are finished. If the miss moves to the new cylinder you need to replace that one coil. Coils don't wear out like sparkplugs do and you do not need to replace them all at one time. Good Luck.
 
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09' CTS4 3.6DI
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Discussion Starter #4 (Edited by Moderator)
to help us help you, please list the mileage and recent work done.
Normally the plugs to use are AC Delco and name brang coils.
It has aprox: 121k miles and i have only had the car for 8 months. The car hasn't needed any engine work since I've had it. I've only replaced a rear wheel hub and brakes and done other routine work such as oil changes.

Others may feel different but get the specific plugs called for by the factory. They must have really checked them out to then say change every 100000 miles. I also have seen horror stories of off brand coils. With that being said, I would change all spark plugs but move the #5 coil to another cylinder ( make it one that is easy to get to without removing the intake again). After you finish and start it again - if no miss = you are finished. If the miss moves to the new cylinder you need to replace that one coil. Coils don't wear out like sparkplugs do and you do not need to replace them all at one time. Good Luck.
Thanks for the coil Idea ! I had not thought about that. Appreciate the feedback!
 

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2010 CTS4 sedan
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920 Posts
You have to hit a LOT of misfires per cycle before a code gets triggered.

Run a mode 6 test - it will tell you how many misfires you have per each cylinder. Don't start moving coils until you have this data - at least then you will know the degree of the impact and you will know how many other misfires you have and where they are. I wouldn't begin to throw time or money at this without more data.

If you don't have a scanner that lets you run a mode 6 test, get one and learn how to use it. I use a BlueDriver (~$100) and it's amazing but there are others out there for a lot less - cheap insurance that will keep your car running well.

The bad news is cylinder no. 5 is one of the hardest to get at. The good news is that even no.5 is really not that difficult.
 

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Go ahead, blame me. Everybody does 🙄
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Others may feel different but get the specific plugs called for by the factory. They must have really checked them out to then say change every 100000 miles. I also have seen horror stories of off brand coils. With that being said, I would change all spark plugs but move the #5 coil to another cylinder ( make it one that is easy to get to without removing the intake again). After you finish and start it again - if no miss = you are finished. If the miss moves to the new cylinder you need to replace that one coil. Coils don't wear out like sparkplugs do and you do not need to replace them all at one time. Good Luck.
No intake removal is necessary for plug/coil maintenance on a '09 CTS 3.6 DI.
 

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**2014 CTS4 Sport Wagon-Luxury**
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one thing you may want to check as well as many times the coil isn't really bad and new boots (wires) and springs available may fix that issue for a fraction of the cost of new coils...

as an example... 2009 CADILLAC CTS 3.6L V6 Spark Plug / Coil-On-Plug Boot | RockAuto

do you know when the plugs were changed last and what kind were used?

Good luck,

Bill
 

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08 STS 1SG HUD ACC F55 AWD, 08 STS 1SG Platinum HUD ACC F55 RWD
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Oops. Did not notice or think about the DI part. Thanks Long for keeping me straight. I putter more with older CTSs.
 
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Go ahead, blame me. Everybody does 🙄
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Oops. Did not notice or think about the DI part. Thanks Long for keeping me straight. I putter more with older CTSs.
NP.
It's the non-DI 3.6 that requires plenum removal for plug/coil work.
 

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09' CTS4 3.6DI
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Discussion Starter #10
You have to hit a LOT of misfires per cycle before a code gets triggered.

Run a mode 6 test - it will tell you how many misfires you have per each cylinder. Don't start moving coils until you have this data - at least then you will know the degree of the impact and you will know how many other misfires you have and where they are. I wouldn't begin to throw time or money at this without more data.

If you don't have a scanner that lets you run a mode 6 test, get one and learn how to use it. I use a BlueDriver (~$100) and it's amazing but there are others out there for a lot less - cheap insurance that will keep your car running well.

The bad news is cylinder no. 5 is one of the hardest to get at. The good news is that even no.5 is really not that difficult.
I have a really cheap scanner that only gives me the codes, I do plan on buying a better one down the line and slowly learning how to use it. I appreciate the feedback!
 

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09' CTS4 3.6DI
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Discussion Starter #11
one thing you may want to check as well as many times the coil isn't really bad and new boots (wires) and springs available may fix that issue for a fraction of the cost of new coils...

as an example... 2009 CADILLAC CTS 3.6L V6 Spark Plug / Coil-On-Plug Boot | RockAuto

do you know when the plugs were changed last and what kind were used?

Good luck,

Bill
I have no idea, sadly there's no record of maintenance I could find for the car saying they replaced plugs or coils.
 

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'93 SedanDeville 60 Special
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314 Posts
Coils today rarely go bad but as mentioned move #5 and the sparkplug wire to a cylinder on the other head and see if the misfires follows along with checking quality of the sparkplug

More common problems is with the DI (fuel injector) that may need a good cleaning or replacement
Check GM TSBs for your vehicle and see if anything related to misfires or DI that require software updates to PCM or replacement
Maybe try a good cleaner like Seafoam, sold like Walmart, auto supply, etc
Put half of it in gas tank, other half either into intake manifold or into the oil
will run rough at first as it breaks up carbon buildup

You can also use GM's cleaner called Top Down, follow its instructions of use
but could even squirt some into sparkplug hole and let sit to breakup carbon

Sometimes there can be short time frame of multi misfires but not enough to trip a P0300 multi misfire DCT

Use a OBD-II scanner that allows you to monitor and/or record like the PIDs I show below, all current and history of each cylinders will help pin down which one(s) are really start of the misfire

Assure good cleaning of carbon buildup as could be #5 is too dirty effecting valves working and closing correctly
Also check no issues with PCV or EVAP which could effect quality of air/fuel mass to cylinders and that injector is not clogged up

592866
 

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09' CTS4 3.6DI
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Discussion Starter #15
592893
592894
592895


The p2601 code has been around since the summer and I'm ignorantly assuming they're not related. But there's the codes my super cheap scanner is returning, i don't know what the other symbols imply if anything.
 

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2011 CTS Coupe Premium
Orlando - We take orphans
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Well the "pending" means all of the criteria for setting the code have not been met but is thinking about it.
The P0305 (cylinder 5 misfire - actually something complicated involving expected vs actual rpm). Could guess at the "monitor status" elements but best to look at the owner's manual (for the scan tool, not the car).

Not the cheapest since Torque Pro is $5 and a BT dongle $12. I never go look at a post-95 car without it. TP can generate and eMail a Mode $06 test which will give you the immediate and long term cyl 5 misfire count toward the end.
 

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09' CTS4 3.6DI
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Discussion Starter #17
Well the "pending" means all of the criteria for setting the code have not been met but is thinking about it.
The P0305 (cylinder 5 misfire - actually something complicated involving expected vs actual rpm). Could guess at the "monitor status" elements but best to look at the owner's manual (for the scan tool, not the car).

Not the cheapest since Torque Pro is $5 and a BT dongle $12. I never go look at a post-95 car without it. TP can generate and eMail a Mode $06 test which will give you the immediate and long term cyl 5 misfire count toward the end.
It'll be cheaper than what I paid for this cheap tool so I'll likely by the app and a bt scanner soon, thanks for the info!
 

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'93 SedanDeville 60 Special
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Yea that is not much help as just a code reader and not a OBD-II scanner
It does show in first photo "freeze frame"
see if you can read and report what it says as the PCM stores information as what other sensors were reporting at the time the P0305 tripped which can be a good clue what was going on

You can get a full scanner not the best but OK, like Amazon for $100 if you want Bluetooth connection to either a cellphone APP and also comes with software to scan and record on a laptop using MSwindows
Both connect to the DLC under the dash

Look at OBDLINK, MX+ in Bluetooth or cheaper is with USB connection versions but only for a laptop
 

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2009 CTS
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My engine is misfiring and is giving me a code for cylinder 5. I have yet to get it checked but under the assumption that it ends up being spark plugs or a coil, does anyone have brand recommendations when I go to buy them? Or should I not worry about the brand when it comes to coils and spark plugs? Thanks in advance!
Most probably are the coils. They will start failing one by one until you will need to replace them all. My experience with Pep Boys and AutoZone units are good, but he original ones will last longer for sure. Check prices for both alternates. I would replace all of them at once if the car has many miles, and replace spark plugs at the same time. Everything should give a more trouble free operation after that.
 
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