RPM's dropping with start - cause?
 

My '08 G35X with 70,000 miles for the past couple of months periodically has a sudden drop in RPM's with starting, usually cold, but not always. RPM's drop to below 1000 and it feels like the car will stall, but it never has, at least so far.

The one thought that crossed my mind is a true throttle body cleaning with chemicals by a certified mechanic. Has anyone else had this issue and/or advise as to possible causes and correction. Thanks.

All cars drop rpm on cold start. mine idles below 600

Thanks for the note. Mine actually drops to about 600 too, and suddenly. Does your's feel like it might stall for a moment? I suppose you may very well be right that it's simply cold.

my 35 does this 1700 to 1500 back to 1700 first start.

If your cold start is at 600rpms, your tb def needs cleaning. You don't need a professional for this, tho. Open the tb, spray some tb cleaner on the hinges and the inner body and start scrubbing with an old toothbrush. Spray again liberally and wipe it out with some paper towels.

Just don't eff with the butterfly too much. If you can open it once and hold it open that one time for the duration of the cleaning, you'll be better off.

Turn the key to acc on and have some hit the gas n clean it.

650rpm is what it should stay at once warmed up from cold, clean maf and trottlebody

This actually does not work..

What you describe can be typical, normal behavior. Most cars, upon cold start, surge in RPM's to about 1500 or so, and then slowly drop as the engine warms up until settling around 600-700 RPM warm idle.

I'm assuming something has changed then to what you perceived as normal startup routine that you may have become accustomed to.

SO my questions would be what is the general state of tune of the car? Does the air filter need replacement? Is the MAF dirty? what type of fuel are you running?

I'm not quick to jump on the TB cleaning bandwagon because at 155K miles i've yet to touch mine and the engine runs like when it had 5 miles on it. However, it wouldn't hurt to pull the intake track off and have a peek.

Honestly, I'm just gonna have to call you lucky on not having to clean your TB. I had to clean mine at around 80k miles cuz it would stall on warm starts. Once I cleaned it really well tho, it never happened again.

I probably am, but it's not like it's spotless either.

However part of me thinks **** will hit the fan if i actually do try to clean it. "If it ain't broke..."

Well, on most cars the damn things are Teflon (or some slippery coating) coated so the carbon can't stick and build up on the hinges. Not sure if Nissan overlooked this somehow or if maybe the machine that sprayed it on was a POS and some got a little, some got a lot, or what, but yeah, if its good to go, I wouldn't touch it cuz tb cleaner will rip that coating right off and you'll have to clean it regularly. Mine definitely needs to be cleaned now and then tho. Its kind of annoying.