With my 2006 G35 AT sedan (stock) I have been noticing a rough idle on startup since the weather dropped below 40 degrees at night. It only does it on startup after it has been sitting overnight or until the engine has completely cooled off. When it starts it stumbles for a few seconds (and has even died a few times) and then generally idles up to normal RPM and is fine from that time on. If I give it gas on startup it will idle up and won't do it, but you shouldn't have to give an EFI vehicle gas to start it. It almost acts like a carboreted vehicle on startup - not a typical EFI on startup... Anyway, I have tried HEET in the tank thinking I might have water in the fuel - no help. I have ran fuel injector and fuel system cleaner through it thinking maybe that would help - no help. I've thought about cleaning the throttle body, but have read some horror stories with doing that, so I haven't done that yet.

Anyone have any suggestions?

Thanks in advance.

 

Cleaning your throttle body would be the first thing I would do. I had a similar problem on startup as you described, so I cleaned my throttle body and it hasn't happened since. All you need is a can of throttle body cleaner, a 5mm allen wrench (double check but pretty sure its 5mm iirc), some clean rags, and it wouldn't hurt to pickup an extra throttle body gasket just in case. Make sure you disconnect the negative battery terminal before unpluging the throttle body or touching the throttle plate and you may not even need to do the idle reset/relearn procedure.

 

I had the same exact problem on my 03 sedan. It was the throttle body. Nissan's throttle bodies are notorious for building gunk up right behind the butterfly valve. Just clean the throttle body and you'll be set.

 

Thanks for the responses, looks like I will be cleaning the throttle body tomorrow.

Thanks again -

 

I experienced the same issue with my '04. Throttle body service didn't seem tohelp. Had a new MAF installed yesterday and it started great his morning. Jumped rith up to 1700-1800 and stayed, working down to 600-700 as it warmed up.

 

I had this issue. On cold startup at 30 degrees or less, the idle was terrible. Up and down and rough. I'd shut the car off and restart and it would then idle fine.

I replaced the battery, problem hasn't been back in over a year.

I suspected the battery was dying as well, so it wasn't a random thing to replace

 

I will have to try either cleaning or a new MAF as the TB cleaning helped some, but not as well as I would have liked it to. Did you try cleaning your MAF, or did you just go straight to replacing it? Out of curiosity, what does a new MAF cost?

Thanks

 

I went straight with replacement as I have a warranty and they covered it with no deductible. I think it was around $350 installed. I'm guessing that is somewhat relative to your location.

 

OP you know what's funny i have the exact same issue and made a thread on it here and my350z. I've tried the same things as well

http://my350z.com/forum/maintenance-...ssed-revd.html

 

use 3M Tune Up Kit. Best thing I have done for my car ! Warm RPM dropped from 850-900 to 650 !