I'd bet it's the tires. The quality of the Continentals were wildly inconsistent, with some riding great and other coming in with all 4 out of round, hence Cadillac's decision to change back to Michelins in the mid-year of 2007.
It does not have Continentals. It has Bridgestone Turanza's. 245x50x18/s. It is the Performance Sedan not the regular DTS. I have the same air pressure etc. Dealer can't explain it either. The speed limiter is also set different. The first one was at 130 MPH. This one is at 123 MPH. I have the build sheets for both cars. They are identical in suspension etc.
There is a GM bulletin on this. It is caused by a brief change in engine settings in cooler weather on warm up when the engine gets to one tick below horizonal on the temp gage. The effect is about 5 exhaust pulses that accelerate the warm up of the cat convertor and reduce emissions. I read the bulletin and was given a copy. You will more likely notice it at a stop light at idle as the exhaust system then is at low flow low pressure. It has never happened under accleration or at highway speeds for me. I suspect it may cause a tap in a slightly loose exhaust baffle but could never get my dealer to check beyond the bulletin. I agree it is a poor "normal" standard for a Cadillac but otherwise I love the car.
Yep, same exact tires. Air pressure is the same. 35 front 32 rear. Really same everything. Both are Performance Sedans. Even same color. White Lightning.
I even went to the dealer and had them print me off the build sheets for both cars so I could compare them side by side. There is THAT much difference in the two cars. I figured something was different about the suspension options. Obviously there is a big difference, or I would not have gone to all that trouble.
They check out (on paper) to be exactly the same. The only differences are the first one had the retractable sunshade for the rear window and no NAV and this one has NAV and no sunshade.
The new one sits higher from the ground then the first one. The first one had more of a hunkered down look. The fender wells were closer to the wheels. That was probably why it rode rough but handled like it was on rails.
The Service Manager worked with the new one for about two hours one day with a Tech 2 and finally got it to lower about an inch all the way around. That helped quite a bit. Made it handle a little better but increased the ride harshness a little also. I will put up with a little stiff ride as long as it handles better.
The first one was more like a BIG 4 door Corvette. Handling on it was awesome but it did ride rough. More than once, someone has remarked, "This car don't ride like a Cadillac." This one rides more like a Cadillac should but doesn't handle like the first one.
I can't explain the HUGE difference in the two identical cars, and (so far) neither can anyone else. I thought when I bought the first one... "Man, this is great. Cadillac got it RIGHT. People will LOVE these cars." Now I am thinking that the first one was an aberation and that THIS one is normal. This one is OK, but the first one was, as Tony The Tiger would say, GREAT.
All thoughts and ideas are welcome.
Jim from Texas
An equipment change doesn't appear on the build sheet. If your first one had a stiffer anti roll bar, stiffer springs, lower springs, etc. and GM changed it mid year to a higher softer set-up with different suspension parts you wouldn't see that. You would have to check part numbers for each car and even then they might be same if they updated their parts computers with the new part numbers already. D3 might have a set of lowering springs to get your handling and lowered look back.
An equipment change doesn't appear on the build sheet. If your first one had a stiffer anti roll bar, stiffer springs, lower springs, etc. and GM changed it mid year to a higher softer set-up with different suspension parts you wouldn't see that. You would have to check part numbers for each car and even then they might be same if they updated their parts computers with the new part numbers already. D3 might have a set of lowering springs to get your handling and lowered look back.
Thanks for the ideas. You are probably right about the build change.
Most people buying the $60,000 (list) Cadillac, would NOT want the hard ride that my first one had.
Anyway, after driving around in the mountains of Colorado for a week on vacation, and throwing it around pretty good, it has somewhat adjusted to my driving style and now seems a lot more firm then it used to be. Or I am getting used to it and just THINK it is.
I know I have seen something on the following somewhere in this forum but I can't find it. I probably am too impatient to wait for a search on this site.Twice when I have stopped at an intersection about 1 mile from my house I have heard a knocking sound that sounds like someone is in the trunk. It happens 5 or 6 times then disappears.Again, I know I have seen this on the forum but can't find it. I believe it was something to do with the fuel system. I would appreciate someone refreshing my memory on this if possible.
"GM Service Information Bulletin Document ID# 1856743 2006 Cadillac DTS; Exhaust Noise on Cold Start Up - keywords 4.6 air LD8 L37 leak pump secondary #PIP3546A -(08/18/2006)
Condition/Concern: Some customers may comment of a pulsing noise from the engine that ocurs during the first minute when starting the engine after sitting several hours. It is actually normal combustion noise caused by aggressive fuel and spark to heat the catalytic converters in order to meet more stringent 2006 model year emission requirements." In my case it happens in cooler weather, car stopped or coasting to stop at low (under 1000 rpm), temp gage at 8 o'clock, get 5 taps in right rear. I mean taps, not pulses but in my opinion the above pulses cause the taps, probably from a loose baffle in the exhaust. If I left the car overnight and started it (cold) at the dealer's I'm sure that 4 out of 5 times I could show the taps. Just haven't bothered to push it. Wont happen under acceleration or on the highway in my case. Otherwise I love the car. I'm 6'-6" and the range of driver seat adjustment was a major plus versus anything else that could also handle two suitcases and three golf bags in the trunk. Good luck all!
[quote=Condition/Concern: Some customers may comment of a pulsing noise from the engine that ocurs during the first minute when starting the engine after sitting several hours. It is actually normal combustion noise caused by aggressive fuel and spark to heat the catalytic converters in order to meet more stringent 2006 model year emission requirements." [/quote]
I would feel better if someone at Cadillac would be able to state that all cars will have to do this and all of them will then sound like a piece of junk clunker when this happens. Until then, you have to ask why my car does this and my son in laws new Saturn does not do it. My 2006 CTS never does this either. Just saying that all DTSes do it is not an answer that should make us happy.
In fact, I would disable this if anyone figures out how to do it.
Again, a great car. Just an interesting manifstation of the "let them eat cake" attitude by Cadillac.
I am still sitting here with police RADAR setting off my Adaptive CC but even the NTSB cares not. I will never have a problem handling the failure when it happens but I may leave a trail of broken cars behind me when they panic brake to avoid hitting me because "I stopped for no apparent reason."
There is a fix for the KNOCKING sound. Cadillac has a TSB out on this. They replaced my EVAP Canister Part Number 15941577 under warranty. Too early to tell if the replacement corrected the problem - will have to wait till the weather cools off to test.
After reading the other posts on this condition I had pretty much resolved my self to accept it as it was so common and there did not appear to be a fix. I had my car (2006 DTS Performance) in for an oil change and while waiting I mentioned to the service writer of the KNOCKING and he knew immediately what the problem was and he told me there was a TSB.
To check if it is exhaust grounding, park car on steep hill, front pointing down hill. Put car in reverse and slowly back up. If it is exhaust, you will likely hear the same noise.
If no hills in your area, go to a parking garage with a steep incline.
There is a fix for the KNOCKING sound. Cadillac has a TSB out on this. They replaced my EVAP Canister Part Number 15941577 under warranty.
BINGO.
I don't know how much quieter the new parts is, but that is exactly what the knocking sound is in this case. I hear it in many different models every day. I frequently take short roadtests and hear this before I come to a complete stop. It is the evap vent turning on and off in a self test.
