06 GT 3500 miles. On starting when very cold the last four days, it stumbles for five to ten seconds then picks up and goes to a normal high idle. It then runs perfectly. With such few miles I can't think of what it might be and yes, it does see WOT several times a day.

 

IT JUST MIGHT BE THAT YOUR RUNNING LOW OCT GAS. MY CAR DID IT A FEW TIMES WITH 87 OCT.

 

Last fill was 91, highest test at this altitude. I did think that maybe that gas was the problem since I had always used 89 before.

 

you're supposed to run 87 on these cars. unless you have a tune.

it's sometimes necessary to warm up the car and let the rpms drop (usually takes roughly about 30seconds to 3 minutes depending on how cold it is)

 

Yes, in the past it would start and go to high idle without the stumble. I will put a tank of 87 in, I am low now, and run that through. If there is a difference I will post. I know I should use the lower octane but was trying to clear the tank for my CAI and tune. But now I am curious so I will go to the 87 and see if there is a difference. The cai won't be here till next week anyway And I can tell the wife I have to drive the H*** out of it and rack up miles before the CAI gets here!! LOL

 

i'm don't have an intake and programmer, but i was under the impression that you get 3 tunes with the intake/tuner. so you can set your tuner to 87 and when it runs out you can put the 91 oct tune on it.

 

I know that. I am tuned! but it’s a bit off since it was pinging on the dyno (it was a dyno day haven’t gone back for dyno tunning. So i been compositing with higher Oct on the 87 tune.

Higher oct cant hurt you going back to 87 isnt gonna help u bob6515 stick to higher oct try letting it warm up for a min or two, there was an issue in the forums a while back with “idle� jumping around it came down to not letting the car warm up, it is a lot more common with car s with headers

 

Could be the O2 sensors and she is running fat for some reason because it is so cold on start up. Take it to the dealer and let them have it overnight (supposed to be real cold the next few days) so they can see what happens. Tell us what they said and go from there. Put any octane in you want but it is useless if you dont have the tune for it! I had the same problem with start up and so have many other FI guys on this site and it was because the tune was rich on startup. Sounds like the same thing to me. Try disconnecting the battery for 15-30 minutes and reconnect and see if that helps your cold start ups maybe the computer needs a reboot and that is exactly what you are doing when you disconnect the battery! Try it it wont hurt and it may help! J

 

i use 93 and never had a problem maybe its the brand you used. i used to have that problem with hess gas

 

I know some FI cars even throw codes during the first few minutes of running. My car stumbles when cold for a mile or so, but I feather-foot it and never had a code thrown up yet. It's due to the system running the fuel fat (choke) but the blower getting 'in the way' of the airflow.