JoeFromPA Posted January 16, 2009 Posted January 16, 2009 Hi all, 10 degrees out this morning when I started her at 6:30am. She's got 16000 miles and was bought in March of 2008 brand new. I'm running Pennzoil Platinum 5w30 and the car was last driven yesterday around 8pm for a 8 mile/15 minute drive, and before that it was 35 miles/45 minutes in the same day. I started her up and she coughed to life....cold and all, but was idling fine. I set the climate control to 85 and low heat, turned the seat heater on, and got out of the car and shut the door. I walked up my pathway and heard the car's idle change dramatically. Instead of the usual cold-running idle of 1500-2000 rpms, it must've dropped to about 500 rpms and almost stalled. The car coughed/idled rough for about 1-2 seconds and then returned to 1500-2000 rpms. The car had been running for about 20-25 seconds when this happened. I've never seen this before. Is this normal? Did something surge? Any ideas? This was the coldest start I've done.... Joe
SeeeeeYa Posted January 16, 2009 Posted January 16, 2009 The coolant heater in the throttle body won't be effective until the coolant itself becomes warm. Conceivably there could have been some issue that the heater is there to eliminate, which it would as the coolant warmed up.
JoeFromPA Posted January 16, 2009 Author Posted January 16, 2009 I'm used to a fluctuating idle in the first 5 seconds or so, as the engine clears itself out and adjusts to the ambient conditions. It was odd that the idle had been stable for 20 seconds and then stopped. I was thinking major the air pump shut off causing a fluctuation... Joe
stingray1967 Posted January 16, 2009 Posted January 16, 2009 How much gas did you have at the time? Were you parked on a hill? Maybe it temporarily starved itself of fuel? Could it have been a slipping alternator pulley? Cold battery, just started is down on power, then if the alternator is slipping and not powering the car, it would die, right? Just brainstorming.
Gatvol Posted January 16, 2009 Posted January 16, 2009 I have had this happen to me before and I have 6800 miles on my 06 LGT. I am am running Mobil 1. Seems it does this on very cold mornings when it has been sitting for a long while. After bout 15 secs it clears right up. So it's the cold.
JoeFromPA Posted January 16, 2009 Author Posted January 16, 2009 Gatvol - This happened 20 seconds after a normal startup, with no one in the car, and resolved itself after about 2-3 seconds at most. Stingray - More than half tank of gas parked on a level surface. Alternator belt didn't slip when the car started, but I guess it COULD have when it started to heat up as it was moving. I think my question is answered: This isn't normal and no one knows for certain what it was based upon my description. I'm going to monitor and see if it happens again. Joe
LGT Dave Posted January 16, 2009 Posted January 16, 2009 This is the third winter since I bought my car and it's always done that every now and then when the temps are below about 20°F. The revs sometimes dip down to 700rpm or below and the engine sputters a bit before jumping back up higher when it's still cold. It even does that sometimes after driving for a few minutes and coming to a stop. It seemed to happen more often after I installed Cobb Stg.1 at the beginning of last year and now that I just got a protune this past November at Stg.2+ it seems even worse. It has always idled rough when the revs dip down like that, but the car has never completely stalled out and after it warms up to operating temperature everything runs just fine. I don't think you have anything to worry about.
Gatvol Posted January 16, 2009 Posted January 16, 2009 Nothing to worry about. That's normal. It has happened to me everyday this week with the temps in the morning. seems to do it at 20-30F. And it fixes itself everytime. And I always set the heat on full defrost and have the real window defogger on. Nothing to worry about man, just the cold.
Backlash Posted January 16, 2009 Posted January 16, 2009 Nothing to worry about man, just the cold. and it's not just your car that does this. with the cold, it can be a lot of things. i wouldn't say normal... but not uncommon either.
rouar Posted January 17, 2009 Posted January 17, 2009 My car does that. It occurs more often during the cold weather, but I also witnessed it once or twice in summer. Freaking scared me the first time it happened, within a week of owning the car.
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