2008-2013 Cadillac CTS General Discussion Discussion, Misfire - Plugs or coil pack? in Cadillac CTS Second Generation Forum - 2008-2013; Thanks for h pics. How exactly oes that mechanism works that attaches he coil pack plug?...
Automobile(s): 2008 DI RWD w/ PREM & PERF Pkg BLK/BLK
Re: Misfire - Plugs or coil pack?
Originally Posted by DaPurpleRT
Just change the plugs would run $300...
Let me clarify: The coils are covered under the powertrain warranty but plugs are considered a wear item. My dealer changed ONLY the two plugs under the coils that went bad as coil failure will cause the plugs to carbon up.
This happens to me too.
Took it into the dealer a while back; they said they fixed it by reprogramming.
Every time I hear that I laugh.... Still does the same thing.
Looks like a DYI project for summer.
I just might change everything. Was it easy to change all plugs + coils? Accessible?
Can anyone recommend better coils + plugs.
I have had many vehicles and have been driving for 35 years and have never had a coil go out until I bought my 2008 CTS4. At 66k my car started running like crap and had a hard time going up hills. It was jerking and you could hear a muffled backfire. Dealer found the number 4 coil had gone out. replaced it and ran like new again. The check engine light never came on. Now at 146k I strarted noticing lower gas economy then a very slight jerking on acceleration mostly when it was cold. this progressed but not as severe as before. Took it to the dealer again and yep, coil but this time the computer wouldn't pick it up and the cars ECM showed no codes. I had to drive the Tech around with his computer hooked up until the jerking started and then he saw misfires on 3 and 6. after further diagnostic it was the coils. Changed them out and runs like new again. So it appears a coil can go completely out like my 1st one and easily be detected or they can go partially out and be harder to detect but eat away at your fuel economy and gradually get worse so you know you have to take it in. The dealer suggested I replace all of the coils. They charge 400.00 per coil to install stating the intake manafold has to be removed to get to the coils. I think its rediculous that these coils malfunction like this. The picture I attached is one of the coils I had replaced today. You can see rust or dirt on the rubber seal that fits into the chamber so it looks like moisture gets past this seal and could be shorting them out.Coil 1024 768.jpg
To the guys who have changed the plugs, did the geniuses at GM torque these plugs down to 100lbs or something? I just tried to get on with a 3/8 ratchet and I applied double the force I've EVER applied trying to loosen a plug and stopped for dear of breaking something because NO plug should ever be that tight!
I have had three coils go bad and the symptoms were always progressively the same. Weak power at 2500, some hesitation, then finally starts to miss at 70 cruise with light throttle. Finally gets almost constant. Doesn't set check engine light until it misfires badly and like three times in a row.
Note that my coils were damaged by a disconnected vacuum hose - air leak. After that was fixed it still took last 2 coils another 6 months to fail.
Runs like a new car with all good coils!
So for a long time I had no codes and it still ran badly.....
I have 185,500 on my CTS and it is doing the same thing, no codes at dealership. They were able to get one cylinder to misfire, I was close to a tune up so I had them replace all the coils and plugs and I am still having the same misfire under acceleration. Mainly after the motor has been running for awhile. Not sure what my next step is to do, the dealership doesn't seem to know what to do either.