Hey guys...

My 2010 G37x has ony about 5700km on it. I'm noticing on a cold start, the engine feels rough, vibrates the car, and rpm jumps up and down a bit until it warms up and levels down. Is this just the nature of the beast? Anybody else feel that the start up is not so smooth in the G?

 

Totally normal.

During a cold start the vehicle will run in a closed loop cycle. During a cold start the air fuel mixture needs to to adjust. As the system starts to get a read on things the rpm will adjust once the sensors send the required information back to the engine computer and it operates in the open loop cycle.


All cold starts in cars are always followed by high RPM's.

 

First 30 seconds - minute is very rough. I usually let the car warm up for a few minutes before I go.

 

Yeah always let the car warm up for a good few minutes before driving it off. Most engine wear occurs during a cold start.

 

Good to hear that it's normal and just the Nature of the beast. I always do let the cars warm up, but this is my wifes, and i get so annoyed when she starts up and just backs out of the garage. Lol.

My TL is actually very smooth on a cold start. It rev's higher for the first few minutes, but not a single shake can be felt.

That's why i was a little worried something may be wrong. Thanks for your help guys

 

do you guys let the car warm up until the needle go below the 1x rpm mark?

 

I wouldn't say that i wait until the RPM get's below 1k, but i wait about a minute or two. I give it enough time for the Oil to flow. After a minute the RPM's will be pretty close to 1k

 

i usually wait for the rpms to drop to ~1200, down from ~1600. this is when the engine quiets down and smooths out. with my custom exhaust the noise on cold starts is booming in my underground garage for the first 15-30 secs. women and children beware!

 

Mine is a little rough....but no worse than the last two cars I owned: 03 BMW 530i and 04 Acura TL. The TL was really pretty bad....but it too smoothed out after a few minutes.

 

Might be rougher because of longitudual engine versus transverse ? More side to side rocking with the former, more front to back knocking(harder to pickup on or feel) with the latter... ?

 

Yep, my brand new 2011 G37 Coupe with only 500 miles on it does that too.

Must just be the cold weather.

 

That actually makes alot of sense, becuase in the G, you can actually feel the car rock from side to side on a cold Start up. Never felt that on any other car. So makes total sense to me.