2007 G35 Journey sedan. A couple of weeks ago I started having a cold start issue (although cold is a relative term in south Texas right now) where it starts, but the idle is only about 500 rpm then after a few seconds or so it will increase to normal rpm of 1800 then settle down to ~700 rpm. I recently did an oil change, spark plugs, and air filters. I did try something recently that has me thinking fuel pressure is not being maintained. I started it up then shut it off after only a couple of seconds then restarted it and it started normally. Possible pressure regulator problem? Car runs fine otherwise. Good power, fuel economy is unchanged at 22mpg.

Tom

 

How does it run at high rpm when it's hot? Any sputter or misfire?

I would suspect the plugs, pull and inspect them, don't just assume because they're new that they aren't the issue. Perhaps a coil pack has a little corrosion on the contact spring up inside the well boot.

 

It runs fine other than the initial start issue. Plugs don't explain it starting normally if I shut it off quickly and restart.

 

If you suspect fuel pressure order the sandwich adapter from Z1 Motorsports. I think I got the adapter with a gauge and a fuel test port all for like $65 a couple years ago.

Still worth pulling those plugs though. Especially if you haven't looked at them in the last 50k miles.

 

I appreciate the input. The plugs are brand new, maybe 1000 miles on them. I have a fuel pressure gauge, just need to make the time to check it. I doubt it's the issue. Perhaps a sticking throttle body? It's behaving better the last couple of days so who knows, perhaps it'll fix itself.

 

There is no fuel line port on the G35, this is why I suggested the sandwich adapter so you can add one.