2006 DTS - Intake Plenum?

[Luke]

Okay, so, my 2006 DTS (currently 165,000 miles) started dinging and saying SERVICE TRACTION CONTROL/SERVICE STABILITRAK every once in a while, about 2 years ago. It wasn't often so I didn't worry too much about it. About 4 or 5 months ago, it started doing it constantly. I have actually known my transmission had been slipping for about a year before the messages started. If punched, it would act like it was popping out of gear then catch. New filters and fluid changed did not fix this problem. I always figured it was the transmission acting up that was causing the messages.

So, I had my transmission replaced about 6 weeks ago. I found one from a 2010 DTS with 24k miles and paid $1,870 said and done for transmission, new LOCKUP torque converter, new starter (just in case), fluids, gaskets, and installation. I think I did pretty well!

Anyway, the SERVICE TRACTION CONTROL/SERVICE STABILITRAK did not go away. When I picked the car up, it had also developed a rough idle.

I've been struggling to find the problem. When the message appears, I get P0171 and P0174. Upon researching, everything on the internet points to a torn intake plenum. My guess is that when they had the intake off, they did not notice a tear in the plenum and removing and installing it made the problem worse.

Here is my question.... everything I have found on the internet and on caddyinfo talks about the plenum leaks on 2000-2005 DeVilles but never have I found a mention of the problem on 2006+ DTS. Has anyone ever heard of this happening on 2006+ DTS?

BTW, even though the installation of the brand used transmission didn't fix the problem, I am happy I had it done. The transmission no longer slips. It shifts BEAUTIFULLY (when the SERVICE TC/STABILITRAK messages aren't present) and should last me many years to come! Other than these problems, this car has been such a great car and I intend to drive it for the forseeable future since the STS-V is not my daily driver.

[Texas Jim]

Okay, so, my 2006 DTS (currently 165,000 miles) started dinging and saying SERVICE TRACTION CONTROL/SERVICE STABILITRAK every once in a while, about 2 years ago. It wasn't often so I didn't worry too much about it. About 4 or 5 months ago, it started doing it constantly. I have actually known my transmission had been slipping for about a year before the messages started. If punched, it would act like it was popping out of gear then catch. New filters and fluid changed did not fix this problem. I always figured it was the transmission acting up that was causing the messages.

So, I had my transmission replaced about 6 weeks ago. I found one from a 2010 DTS with 24k miles and paid $1,870 said and done for transmission, new LOCKUP torque converter, new starter (just in case), fluids, gaskets, and installation. I think I did pretty well!

Anyway, the SERVICE TRACTION CONTROL/SERVICE STABILITRAK did not go away. When I picked the car up, it had also developed a rough idle.

I've been struggling to find the problem. When the message appears, I get P0171 and P0174. Upon researching, everything on the internet points to a torn intake plenum. My guess is that when they had the intake off, they did not notice a tear in the plenum and removing and installing it made the problem worse.

Here is my question.... everything I have found on the internet and on caddyinfo talks about the plenum leaks on 2000-2005 DeVilles but never have I found a mention of the problem on 2006+ DTS. Has anyone ever heard of this happening on 2006+ DTS?

BTW, even though the installation of the brand used transmission didn't fix the problem, I am happy I had it done. The transmission no longer slips. It shifts BEAUTIFULLY (when the SERVICE TC/STABILITRAK messages aren't present) and should last me many years to come! Other than these problems, this car has been such a great car and I intend to drive it for the forseeable future since the STS-V is not my daily driver.

Luke,

On your model car, the INTAKE BOLTS are known to get loose... tighten all the intake bolts and see if that helps with the P0171 and P0174.

[IceCold]

Okay, so, my 2006 DTS (currently 165,000 miles) started dinging and saying SERVICE TRACTION CONTROL/SERVICE STABILITRAK every once in a while, about 2 years ago. It wasn't often so I didn't worry too much about it. About 4 or 5 months ago, it started doing it constantly. I have actually known my transmission had been slipping for about a year before the messages started. If punched, it would act like it was popping out of gear then catch. New filters and fluid changed did not fix this problem. I always figured it was the transmission acting up that was causing the messages.

So, I had my transmission replaced about 6 weeks ago. I found one from a 2010 DTS with 24k miles and paid $1,870 said and done for transmission, new LOCKUP torque converter, new starter (just in case), fluids, gaskets, and installation. I think I did pretty well!

Anyway, the SERVICE TRACTION CONTROL/SERVICE STABILITRAK did not go away. When I picked the car up, it had also developed a rough idle.

I've been struggling to find the problem. When the message appears, I get P0171 and P0174. Upon researching, everything on the internet points to a torn intake plenum. My guess is that when they had the intake off, they did not notice a tear in the plenum and removing and installing it made the problem worse.

Here is my question.... everything I have found on the internet and on caddyinfo talks about the plenum leaks on 2000-2005 DeVilles but never have I found a mention of the problem on 2006+ DTS. Has anyone ever heard of this happening on 2006+ DTS?

BTW, even though the installation of the brand used transmission didn't fix the problem, I am happy I had it done. The transmission no longer slips. It shifts BEAUTIFULLY (when the SERVICE TC/STABILITRAK messages aren't present) and should last me many years to come! Other than these problems, this car has been such a great car and I intend to drive it for the forseeable future since the STS-V is not my daily driver.

Luke,

On your model car, the INTAKE BOLTS are known to get loose... tighten all the intake bolts and see if that helps with the P0171 and P0174.

I have a 2005 Deville and I just had the same exact problem about 30 days ago. I solved my problem with the following and it cleared both codes.

APDTY 022121 Throttle Body To Intake Manifold Plenum Coupling Rubber Boot

My Plenum Coupling Rubber Boot was torn at the very bottom.

Hope this helps!

[Luke]

The saga continues...

In trying to find the cause of my engine running rough and codes P0171 and P0174, here is what has been done...

used transmission with 24k miles (this is when it started running rough)

intake gaskets

plenum

valve cover gaskets

EGR valve and gasket

throttle body

MAP sensor

MAF sensor

alternator (volts were dropping and causing the engine to rev)

gas cap

I know it just sounds like I'm throwing parts at it but this has turned into more of a hobby. I've already replaced it with a 2008 DTS performance. I buy new OEM parts cheap on eBay and put them on myself so I don't have a whole lot of money into it. And I figure, once I find the problem, I'll practically have a new car. LOL

Anyway, I just finished replacing the alternator today. If voltage drops, the computer raises idle to around 1200-1300 in my case to try to increase voltage. This happened often. If in traffic, it would fight the brakes and the engine would run hot. One day, on the way to work, it decided to rev right after a car in front of me stopped. I had the brake pedal on the floor and barely got stopped in time.

So, no more revving. But, I still have P0171 and P0174. What else could it be? I did take it to Sewell Cadillac in Dallas (I do NOT recommend Sewell) who charged me $500 to change the EGR gasket. I fought it and got a full refund. They couldn't find anything causing the poor idle.

Anyone have any ideas? Catalytic converter? AIR injection check valve? Purge solenoid?

I'm at a loss.