I have a question related to cold starts and what the initial RPMs are on your V8. I only have 1,200 miles on my car so far. When I first got it, whenever I would fire it up after it sat overnight or 4 hours or more, it tach would jump right to 1,500 and sit there for a few before coming down to the normal idle RPM (750) as it warmed up.

About two weeks ago I took the car to a car wash, the kind where they drive it thru for you and I think the bastard stalled it out at some point (manual). When I got in it to leave and cranked it up it now only went to 1k and then slowly crept up to like 1,300 before coming down to idle. It just didn't sound right, especially since the car should not have cooled down much in 30 minutes. Ever since this every cold start it does this same thing, no longer does it start up at 1,500, rather it slowly creeps from 1,000 to 1,500 before coming down.

I have it in the dealership now to look at that and also replace the blown rear speaker. The guy left me a message today talking about how that is normal for the car as it picks up new parameters the more you drive it. I just dont think its right. Does anyone elses GT do this?

Sorry for the long explanation, its just really weird.

 

my car does the same thing. i just wait for the revs to come back to normal and continue about my day. i just assumed it was fine.

 

It's never very cold here in San Diego but in the morning my GT goes straight to about 1,250 rpm then 15-20 seconds later it goes to closed-loop mode and the revs drop to 1,000 rpm. Pretty soon after rolling it's down to the standard 750 rpm idle.

I think what you were seeing is the closed-loop kicking in. The engine has tables in the computer telling it what air-to-fuel ratios to aim for when running with modifiers for temperature and other conditions. When you first start up (warm or cold) the lambda sensors (which sense how much oxygen is in the exhaust gas and hence allow the engine to modify the fuelling to hit the target ratio) are cold and need to warm up to work. This takes 15-20 seconds. The engine uses its tables (plus accumulated adaptive learning data) until the sensors are warm then modifies the fuelling to hit the target air-to-fuel ratio.

It looks like after your car wash the revs were lower due to the prevailing conditions and engine temperature then the sensors cut in and asked for more fuel to hit the target AFR thus increasing your idle revs for a short time.

Whether I'm way off or not, it doesn't sound like a problem. Your car is probably still quite tight with only 1,200 miles. I found that mine really developed since new and I'm at almost 6,000 now and the engine really feels great. Enjoy!