I recently read the post in the "General Tech" pages regarding rudeness when the available techs on this site take time to help people out. Althought I am a new member to this site, I want to say that I think that people who use knowledge from this site and take off without showing appreciation or sharing the info for others is absurd and I will not take part in such an action. I am very appreciative of any information/guidance I can take from this site and I will share my experiences with all in hopes that maybe it will one day help them. With that said, I am hoping that someone can step in and give me a few words of advice with the problem I am having with my car as I am getting pretty frustrated (not to mention broke) trying to diagnose and fix it.

So...the problem is this:

I bought my 2005 Cadillac Deville about one year ago, the car had about 45,000 miles on it at purchase. All went well until about 6 months into my ownership. This is very hard to describe, but the car started to make these "jerking" feelings when at a stop. It started out just when the car was cold but now it does it when the car is warmed up as well. About 5 minutes after starting the car will start jerking and "bucking" randomly. This happens sometimes constantly when at a stoplight or stop sign.

How I have addressed the problem so far:

So far I have had my car into a trusted mechanic and he took a drive with me and feld the jerking. He immediately said that a cylinder was misfiring and did some diagnostics to confirm that cylinder 3 was misfiring. He replaced spark plugs and put some fuel injector cleaner in. He also replaced a couple of sensors in the car that deal with the position of the cylinders. All of this was done to the tune of around $800. THe car did not jerk for the short time he had the car after that but started doing it shortly after.

Aside:

My mechanic has an internet database of common problems with car makes and models and how they were addressed at repair shops nationwide and this problem showed up as one of the most common for the 2005 Deville.

Another odd problem that I have with this car that my mechanic thought may be tied to the cylinder problem is that whenever my electronics are on (i.e. heated seats, cruise control, etc) I get a fuzzy interference noise in the speakers only when my satellite radio is being used. Perhaps associated? Im not sure.

Like I mentioned, any information anyone can offer is greatly appreciated and I hope that you can overlook my rookie status in the forum. No one seems to know whats wrong, please help!! I have heard rumors that it may have something to do with coil packs..?

Sincerely,
Jack

 

codes? If misfire still present on #3 it likely will need coil assembly.

 

I cant remember the code exactly, I am guessing that the misfire would be something on the order of "P0303"? My mechanic brought up this idea when my car was in to the shop but said he wanted to try a couple other ideas first before going for the coil assembly as they are pretty expensive, but after what it costed Im guessing that the coil assembly would have been the more economic route from the start. Because I am interested, how does the coil assembly work and is it simply a part failure that causes this misfiring problem? I was told that this has been a fairly common problem with this model car. Thanks for the insight, I really appreciate it.

I go to college about 6 hours from my hometown where I have always had work done on my car unless its urgent. Before the 2005 Deville I had an absolutely beautiful 1993 Deville that was white with a red leather interior and it was in truly mint condition. I loved that car and took great care of it. I took it to the Cadillac dealership in the town where I attend college and the guy that changed my oil didnt put the oil filter on properly so about an hour after the oil change I ended up back in their shop. Long story short they ended up buying my car from me (I took a hard loss) and I refuse to go back there for any help or service. I will not be able to get my car back into the shop at home until about Easter weekend unfortunately.

Many thanks,
Jack

 

If you search net you will find the answer in detail. Basically the primary windings get battery / operating voltage which induces voltage in the secondary windings. When voltage to primary winding is turned off voltage in secondary coil collapses causing spark or discharge of energy. In the coil pack the there is IC to turn coils on and off. You need to respect the power they can produce. DIS now a days can have a unlimited voltage potential, the higher the source voltage going in the higher the output - meaning more than 100kv in a vehicle with overcharging charging system.

 

Thanks for your time and insights. I have an appointment for my car this Friday, so hopefully Ill get things taken care of. Any idea what the coil assembly costs?

Thanks again,
Jack

 

Hey just wanted to say thanks for the help! I had a new coil assembly put in and the car runs great!!! My mechanic gave me the old coil assembly and marked the one that was bad. That way if it happens again I can replace the bad one with a good one from the old assembly. This is a great word of advice for anyone else with this problem to ask for the old part! The coils cannot be purchased individually but rather in the entire set. Can save a lot of money!!! Thanks for the help!!

 

missleJ,

Thank you very much for posting this a couple years ago. I am having the same issue on my 05 Cadillac. I have replaced the plugs, air filter and fuel filter. I am now in the position after seeing your post in considering buying a coil pack assembly. Just curious did the problem ever resurface? I do not have a check engine light on and was told the diagnostics could not be done. The car is daily driver and it does it primarily at a stop sign although it has good power once I get it going.

I sincerely appreciate you posting the resolution and I hope this helps with my car.

Regards,
02and05Devilles

 

Problem solved here as well- Coil assembly replaced and the problem solved.

 

I have a 2005 STS with the 3.6. I have a constant problem that when accelerating the car will lurch or buck like a really bad misfire is happening. Usually no lights flash. I have even been driving down the street and Onstar has called me asking if everything was ok?! I couldn't tell if anything was wrong but they said that the engine was misfiring...no idiot lights. I took the car to the dealer and they replaced the coil and it seemed to fix the problem. But, then it came back, probably worse. No codes. Today it bucked so violently that the check engine light blinked then stayed on solid. I called Onstar but by the time they were able to do a diagnostic the light was off and the car was running fine. They said they couldn't see any codes and to call back when the light was on. HELP please.

 

How long ago did you have your vehicle into the dealership for this?

Michelle, Cadillac Customer Service