[kman779]

Hey guys, I have looked all over Google and searched through pages of threads in the forums here but I cannot find a remedy to my particular problem. I have a 2006 DTS (not performance) with 1235XX miles and I just got back from a 1600 mile trip. About 3/4 the way through the trip I began to notice a rough idle which is especially noticeable when it is in gear and I am waiting at a stop light. It will run fine for a bit then the rough idle comes and it kinda jumps as I hold the break. I also began to feel it doing the same thing when I am on the interstate doing around 65mph and going up a hill. To me it feels like a misfire. I did not have a check engine light come on the entire trip, but it still is acting up and I don't want to take it to a dealer if it is something relatively simple.

I read plenty about the horrible tear in the intake plenum that has plagued the 2000+ Devilles, but all the information I find only applies to vehicles up to 2005. Also, #8 coil and all plugs/wires were replaced in March of 2012 by the dealership. I then had all the plugs changed again last August after the dealer found a crack in one of them.

I would greatly appreciate any information or suggestions to help remedy my problem. I really enjoy my DTS, but if I don't find a solution very soon she will be taken to the dealer and traded in. Thanks!

 

[mike5514]

not much to go on here but for a start assuming the ign. is ok.

bad gas
fuel filter
fuel pressure regulator

First go to autozone have them scan it (free) and come back with the codes. Mike

 

[grullon10]

The fuel filter from 06 on is in the fuel pump that mean that they do not have a fuel filter. Do you have a the check engine light on.

 

[kman779]

No check engine light at all, and my local auto parts store (we don't have Autozone) said they did not get any codes. I use mid grade fuel and the past two tanks since I noticed the problem I ran a can of seafoam through to see if it would clear out a possible injector blockage or something that could be causing the problem.

 

[kman779]

Took it to the dealership this morning and just received a call from them. They stated that they pulled a code of multiple random misfires and that my caddy needed coils for the entire rear bank of cyclinders (1,3,5,7) and they found a crack in a plug on one of the cylinders. Any idea what could cause an entire bank of coils to go bad?

They wanted $685 to replace the 4 coils and all the plugs. How hard would it be for me to replace the coils myself or should I just let the dealership handle it and let me bank account drain out for their labor cost?

Please reply ASAP so I can get back to them! Thanks

----------

They wanted $685 to replace the 4 coils and all the plugs.

I called my local auto parts store as well as looked on ebay and look like I can get some ACDelco coil packs for $50 a piece so I think I will order them and install myself. I would appreciate any knowledge or tips or replacing the coils though. As I understand it, the procedure is simply disconnecting a bolt and a plug then putting the new ones back on.

 

[Ozlander]

All the coils were replaced a year ago by the stealer and now half are bad again????

Might be looking for a new stealer.

 

[kman779]

My apologies, I mis-typed the first post, only the #8 coil was replaced last March. I fixed the original now, thanks for catching that.

 

[Superjim]

Hard to believe all 4 coils are bad...
I would have it checked somewhere else before dropping that much money on just the dealers say-so...

 

[Andrew224]

Changing the coils / spark plugs is easy as long as you have at least a basic knowledge of mechanics. You should be able to pick up AC Delco coils for about $45 / each and a set of AC Delco plugs should set you back about $40. So around $220 for parts and should take you like an hour or so.

There's a good Youtube video on how to do it. Just search Northstar sparkplug change.

But why change all the spark plugs?.. They are new and should last 100k miles. Just change the cracked one and see if that doesn't solve the issue. Then change the coils if you want to see if that remedies it. Or take it to another dealership for a second opinion.

I'm having similar problems (engine misses when at steady rpms at times and has an idle that drops real low and then catches itself but sometimes stalls). No Check Engine Light. I'm going to try changing the crankshaft sensors to see if that clears it up. Someone else had similar symptoms and had an 02 sensor replaced which cleared up his problem.

 

[Superjim]

I called my local auto parts store as well as looked on ebay and look like I can get some ACDelco coil packs for $50 a piece so I think I will order them and install myself. I would appreciate any knowledge or tips or replacing the coils though. As I understand it, the procedure is simply disconnecting a bolt and a plug then putting the new ones back on.

http://www.amazon.com/ACDelco-D596A...r=2006|2006&carId=001&n=15684181&s=automotive

 

[mike5514]

I dont recommend replacing parts as a form of trouble shooting most cases especially with intermittent problems.

The fact that the dealer said a bank of coils were bad seems odd and another cracked spark plug?

You can make a lot of checks with a digital multi meter . Mike

 

[Andrew224]

As I understand it, the procedure is simply disconnecting a bolt and a plug then putting the new ones back on.

Yes, disconnect the wiring via a connector. There is one 10 mm hex head bolt (if I remember right) holding the ignition coil in place. Once that is out, you just pull the coil up and off the sparkplug and that it.

 

[danog]

If the dealer replaces the plugs last August and you have less then 12k on the new plugs, the dealer has to replace the crack one under warranty. They have to guaranty there work for 1 year or 12k miles. It’s in the dealer’s contract to GM. It seams odd that a plug is cracked every 5 months. Ask if there was oil on some of the plugs.

Find out witch Coil is bad, and only replace that one.

You have to find out if you have the first gen coils or 2nd gen coils. You can tell by the plug connector on the coil.

 

[kman779]

Thanks guys for all your input. I ordered 4 AC Delco coils for $44 a piece and then order 4 of the AC Delco Platinum plugs. I figured I might as well replace eveything while I am back there and have it torn dapart. I can always return the coils or whatever else I end up not needing/using.

 

[kman779]

I finally got around to pulling the coils and plugs out and when I pulled the plugs out I noticed that there was some oil on a couple plugs. I would assume that this could be causing the random misfires that I am getting. Any idea as to where the oil is coming from and what needs to be done to remedy the problem?

 

[MoistCabbage]

Oil in the plug wells is common. The plug well O rings tend to seep over time, what's in there took 7 years to accumulate. Oil is an electrical insulator, it's not the cause of your misfire.

 

[Submariner409]

Truth ^^^^

Also common in the earlier Northstars. Google "cadillac forums northstar cam cover seals".

 

[Andrew224]

Here's an update on my problem... I took my '06 DTS in to another larger Cadillac dealer. They found the MAF sensor to be out of calibration and caused the engine to run lean. The rough idle caused an error in the Stabilitrak system which would trip the Service Stabilitrak warning message at times. They still need to road test it a bit to make sure the issue is resolved before I pick it up.

 

[Cadillac Customer Service]

Here's an update on my problem... I took my '06 DTS in to another larger Cadillac dealer. They found the MAF sensor to be out of calibration and caused the engine to run lean. The rough idle caused an error in the Stabilitrak system which would trip the Service Stabilitrak warning message at times. They still need to road test it a bit to make sure the issue is resolved before I pick it up.

Thank you for the update, Andrew! I hope you'll let us know your observations once you pick it up, and don't hesitate to contact us at Customer Service if you would like assistance working with your dealer. I'm reachable via email at [email protected].

Best,

Katie
Cadillac Customer Service

 

[Andrew224]

Thank you for the update, Andrew! I hope you'll let us know your observations once you pick it up, and don't hesitate to contact us at Customer Service if you would like assistance working with your dealer. I'm reachable via email at [email protected].

Best,

Katie
Cadillac Customer Service

Katie,

Thanks for checking in. I was very happy with the service I received from Cadillac of Naperville. They did a good job of diagnosing an intermittent problem that another dealer was unable to. They also called my attention to some other issues that need to be addressed in the near future.

Andrew Armitage