'03 3.2 AT lux package currently with 26kmiles. Purchased July 05 with 16k miles. Car has run great until yesterday.

Issue:

While on a trip to Chicago yesterday pulled into a toll booth. Car was running very rough.
AC was on and in gear.
Put car into neutral it smooths out/runs normal
Turn AC off and it smooths right out
Premium gas is always used.
Ran tank down to almost empty and refilled with Shell Premium on the way back but issue is still there.
Called dealer this morning and he thinks maybe some bad gas:confused:. Try some dry gas, run it over the weekend and see what happens. I have a service appointment on Tuesday morning for other work.Anybody have any thoughts? I've searched the forum and there are some discussions on 3.2 rough idle issues and possible TSB fix but I found nothing similar to this issue. The thing that bothers me is that this is a new issue for this car. Idle and performace until now has been great!!! Even during last summers heat. I do realize that AC will cause a little rough idle but again this is a brand new issue and very pronounced.
Thanks in advance

I have 03 23,000 miles no problem with idle. Something broke on yours dealer will fix it on Tuesday. :thumbsup:

'03 w/ 70k kms ~43k miles, got the usual idle TSB computer update that bumps the idle speed up by 50rpm or so.

No problems whatsoever idling with A/C on.

hmmm, i have just over 40k miles on mine (bought with 27,5k) and i havent had any idle issues. mine is also a 03 Lux. Sport.

I've got 57000 miles on my '03 Lux; no problems.

some of us with 03's have experienced a rough idle. As B0000rt said, there is a TSB to have the DIC flashed to raise the idle level about 50rpms to fix the problem

It also covered early production 04's (like mine) with the 3.6.

yep ECM flash at the dealer and you "should" be ok. I got the flash, have a manual tanny and still run a little rough at the light. I have been told the 3.2 is that way.

TSB's are only covered under the manufacturers warranty? or can they be applied outside of standard manufacturers warranty?

You'd have to ask your dealer about cost, but it takes about 40 minutes to flash the ECU, since the total engine control software get's updated (several megabytes over a 9600 baud link via the ODB2 port). It basically raises the idle speed 50 or 100 RPM, and does a few other things (runs a fan for a while after you turn the AC off to clear the moisture out of the condensor to prevent mildew in humid climates, among other things).

This is definitely a long knows issue on the 3.2, and easily solved. With an engine that peaks at 6000 RPM, it's not easy to get a smooth idle. The 3.6 is better since it has Variable Valve Timing.

Thanks to all for the advice. It's going into the dealer in the morning for service work and will discuss the issue including the TSB. Once I get it back I'll let y'all know what they find (if anything).

To all
Well, had it into the dealer this morning and they ran the diagnostics etc. Seems the car already had had the ECM "upgrade" prior to my purchase last summer.

So the problem is still there. Although I will admit that after driving it over the long weekend and ~200 miles with 2 bottles of dry gas in the tank it seems a bit smoother but not as smooth as before this problem cropped up late last week.

For now and at the recomendation of my dealer I'm going to add more dry gas at the next fill up, run that through the system and see if it improves things. If not the dealer indicated that they will dig further.

Stay tuned and thanks again in advance for the help/suggestions.

what is "dry gas"?

Pmpott -

A. Dry gas is basically alcohol, ethanol to be specific. The ethanol mixes with the water and keeps it from freezing when the temperature drops and makes it burnable. So yes, it does serve a very useful function. The engine doesn't matter. It could be a little three cylinder Geo Metro or the V-16 Cadillac. Condensation will still form in the gas tank and you will need the dry gas to keep it from freezing so it can be burned.

Also works in warm weather in case you get some gas with a bit of water in it. Any auto store (and some supermarkets) carries it.

Check out the below link.

http://autorepair.about.com/library/faqs/bl677e.htm

Mine also has issues with rough idle. Passengers can even feel it. Was told buy more than one Caddy mechanic that its normal on the 3.2 (wish I had the 3.6).

Mine also has issues with rough idle. Passengers can even feel it. Was told buy more than one Caddy mechanic that its normal on the 3.2 (wish I had the 3.6).

Visit a different mechanic.

How is your coolant level?

Does the A/C still blow cold air or is it noticeably warmer than before?

Shit, I'm going to get killed on this one... but how do I know if I have a rough idle?.... :rolleyes:

Shit, I'm going to get killed on this one... but how do I know if I have a rough idle?.... :rolleyes:

Typically you will feel a vibration when you are stopped at a light, hence the rough idle. A lot of things can cause a rough idle.

Mine usually happens after it is warmed up, sitting at a light or stopped. The dealer has done the update and has told me to use better gas, however it still runs rough (a little bumpy). I believe it is a known issue.

Typically you will feel a vibration when you are stopped at a light, hence the rough idle. A lot of things can cause a rough idle.

I can't say I have that on mine.... :)
I will check again, but hopefully they either already did the TSB on it or just was never a problem....

Visit a different mechanic.

How is your coolant level?

Does the A/C still blow cold air or is it noticeably warmer than before?

Coolant level is fine and AC blow's cold. No issue with either. I've now added 2 bottles of FI cleaner and run them through almost 2 tanks of premium gas on a trip yesterday to Pittsburgh and back. Still running rough especially when the car has been running for a while.

As I discussed in my original post this is a new issue and has not been there before.

I'll head over to the dealer later today or on Monday to further discuss the issue. My dealer and service guys are real good and will work with me.