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2007 CTS
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Discussion Starter #1
My 2007 CTS has 65,000 miles and over the past week some issues have come to life. The car has started to have a hesitation/bogg down when accelerating. A rattling sound also is made when the hesitation in accelerating. It also has started to idle rough. These issue only come up when driving around town at speeds under 40 mph. When driving on the interstate it has no issue. I have not had a check engine light come on. Any suggestions on what could be going on?
 

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CTS 3.6L 2005 80,000 Miles
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983 Posts
sounds like misfires, normally this is caught with a CEL P0300 but not always. I wouldn't drive with it this way for too long as misfires from bad coils can kill a CAT which turns a $100 repair to a $700 repair.
 

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2007 CTS
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Discussion Starter #8
I have opened the hood. When in park it runs perfect. When you are driving at low speeds the throttle hesitates, bogs down, and the rattling begins. I just changed all of the spark plugs yesterday.

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I have opened the hood and when in park the car runs perfect. When driving at low speeds the throttle has a hesitation, bogs down, and a rattling begins. I just changed the spark plugs yesterday and this problem is still happening.
 

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Have someone give it has when in park and check where it's coming from. Maybe take a video for us. Could be the honeycomb inside the cat breaking up but normally you hear that even at idle.
 

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My 2007 CTS has 65,000 miles and over the past week some issues have come to life. The car has started to have a hesitation/bogg down when accelerating. A rattling sound also is made when the hesitation in accelerating. It also has started to idle rough. These issue only come up when driving around town at speeds under 40 mph. When driving on the interstate it has no issue. I have not had a check engine light come on. Any suggestions on what could be going on?
This is my exact issue. No codes but under 45 mph its sticking and hesitating. 2007 STS with almost 77500 miles. For the past couple months I was working from home and then for the past three weeks I've been driving highway speeds between 70 and sometimes 80 miles an hour for short spurts of time to a job I took that is approximately 12 miles away. I don't know if driving like that 5 days a week 3 weeks straight has been rough for my car that's not used to that especially with accelerating to such high speeds but when I read your post it's the most I found that is a mirror image to my problem. Sadly reading your entire thread I'm finding that there was no resolution it doesn't seem like you ever got a concrete answer from anyone. Now currently my car is due for an oil change and we're doing that today. It technically doesn't need a tune-up yet but if I have to do that I will. But it has been run through a code reader and nothing is coming up. One piece of info I want everyone reading this to know is a few days before this happened I did get a check engine light which was related to a very loose gas cap I replace the gas cap for the very next day and we cleared the code and didn't have a problem for several days. I don't know if from the loose gas cap something got into my fuel system? But as I write this I'm having the air filter changed and the person doing it couldn't believe how dirty it was so there's a possibility it was what I saw many people telling other drivers to check when they had similar hesitation issues which is the mass airflow sensor so we're going to finish putting in the new air filter give it an oil change which my computer in the car is reading that my oil is functioning at 40% so we intended to do an oil change anyway and I can get back to everyone but I specifically wanted to comment because I was very curious about what your outcome was and what your specific problem ended up being if you were ever able to find out.? Thanks in advance for anyone that has any suggestions or information. I've often come to this webpage and looked up questions I've had as this is the first time I've ever owned a Cadillac I bought it in September of 2019 it is now June of 2020. I did not frame of time I haven't driven it that much because I was laid off in November 2019 and then the whole pandemic happen where we all stayed in our house is from March until about a week ago! But at the same time I did also buy this car from a sheisty car dealership that lie to me about if conditions and problems so I wouldn't be surprised if there were hidden issues that are now just going to start popping up so just letting everyone know that when things do start to slowly peek out from under the hood that was hidden from me by the seller you guys have been a great help so thank you in advance to everyone that has posted on this page so far. Today was the day I finally decided to actually become a member!
 

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2007 CTS 3.6 >131k miles
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701 Posts
Welcome to the forum! However this is the CTS forum so some info may be irrelevant to your STS. Regarding your current problem, this is likely a basic mechanical troubleshooting issue.

Several things can cause the rough idle, so it is hard to diagnose over the interwebs. A new air filter is a good start, and a full time up is probably worthwhile (new plugs, etc), clean the MAF sensor and throttle body, etc. It is always possible that the problem is more extensive but these are the easy/cheap things to rule out first.
 

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2005 Base CTS work at Pullen solenoids Glass Factory for 36 and a half years
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170 Posts
For you being a newbie a MAF sensor is a mass airflow sensor and if you do clean it make sure that you don't use carburetor cleaner but use MAF sensor cleaner. Carburetor cleaner will mess them up a lot of times. Put some fuel injector cleaner in your gas tank also. Running at the speed you're talking about Will Do no harm unless you do have some problems with the engine that could hurt it.

Roy
 

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2007 CTS 3.6 >131k miles
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701 Posts
@TA Coupe thanks for clarifying my jargon! I sometimes forget things like this and start speaking in tongues!

@TA Coupe also mentioned fuel injector cleaner...in my experience, the only inexpensive one that really does much is Techron complete (black bottle; get the 12 oz bottle at Walmart or any parts store and dump it into a full tank of gas). Another thing to check is vacuum hoses. Even one leaky vacuum hose can cause a rough idle.

Edit: one more thing...please let us know how it is running after the oil change. I now routinely check my oil at every gas stop, but this was not always the case. When I bought my CTS the 3.6 engine used some oil if I drove freeways a lot, and idled rough if the oil level got too low. Keeping it topped off maintains smooth operation and prevents premature damage to the timing chains.
 

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2005 Base CTS work at Pullen solenoids Glass Factory for 36 and a half years
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170 Posts
The cheapest place I have found to buy Techron is at Costco. They used to sell it in a six pack and it was almost half the price of other places. I haven't bought it in quite a while because I bought a gallon of Lucas Fuel Injector Cleaner and it seems to work pretty good. Every once in awhile I will get a rough idle if I forgot to put some in for a couple of months and when I put it in it seems to clear up pretty quickly. Whereabouts are you located? That way maybe someone close to you can give you some help if you still need it.

Roy
 

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We use the lucas. The old air filter was filthy so we replaced it. Cleaned everything with the proper cleaners. Still an issue. We got cut short due to a storm yesterday so doubt the oil change today. I'm just baffled that my dash is showing NO LIGHTS and the vide reader is saying my car is fine!!???!! Its like just guessing and without codes a mechanic will just guess too. Frustrating.
 

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2007 CTS 3.6 >131k miles
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If everything is cleaned and otherwise in good condition, I suspect either a vacuum leak or oil issue. Is the oil at the correctly level now? Also, how many miles do you drive between oil changes? If either low or degraded oil is the problem, the oil change should smooth things out. If it does not, this would suggest to me that you have a vacuum leak somewhere; or possibly a deeper problem but rule out the simple stuff first.
 
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