Clean TB and get a pressurized fuel injection system cleaning. I do this every 15,000 miles and results are noticeable. More power, smooth idle, gas mileage boost. As I reach the next 25,000 the rough low idle etc. begins to return. Been doing this for years and it works well.

 

That's a good point. The technical articles I read never specifically mention the TB/VVEL system behaviour at idle.

edit - OK, I did some reading on BMW's Valvetronic system which is similiar to VVEL in that it eliminates the need for a conventional throttle butterfly since it controls engine output by continually varying valve lift and timing.

In Valvetronic the throttle bodies only defualt to open after the engine has reached operating temperature. That means when the engine is first warming up the throttle bodies are used to assist in airflow control.

So, it's quite possible that VVEL works in a similiar fashion and that the throttle bodies are used while the engine gets up to operating temperature and then airflow control is fully passed over to the VVEL system.

 

I'm also having the same problem , whenever i stoped; rpm drop to 400-500 rpm, car vibrate for a second then it go back to 800-900 . i am thinking to replace the TB , i noticed many of g37 coupe ( 08 models) having the same issue with TB.

what do you think guys ? should i replace them ?

Cleaning the TB its not a solution , I've tried that many times.

 

BTW , i replaced the air flow sensor lately , but nothing changed.

 

I'm having the same issue. I'm running the Stillen G3 intakes, but I have cleaned my MAF sensors and had to recalibrate the idle, without any luck. I'm going to the clean the throttle bodies and clean the filters and try again. We'll see if that fixes the issue.

 

been having this same issue for about the past 2 months. It used to do it about once a day, now it does it at nearly every stop light/sign. Mine only drops about 100rpms and then goes back to normal after 2-3 seconds. I also just changed my oil and filter and continue using Eneos 5w-40, changing strictly every 5k miles. Just got off the phone with my service advisor after reading this forum and he said he thinks he remembers a tsb on the 07-08 sedans. Taking it in on Friday to see whats going on.

 

My 2008 G37 has been doing that since 27k and i finally figured out the issue. I had to have my idle bypass valve cleaned and the issue stopped for me. its been about a month since its happened last. I have had it in the shop about 20 times and they could never fix it. I thought i would pass this along since it seems to become more of an issue.

 

Same issue with my 09 X Coupe at 40k. Irritating to say the least.

 

Did it fix your issue?

 

Exact same issue here on a 100% stock 08 G37S. I am also having problems with the car when doing a "warm start", after I've driven the car and it's been parked for awhile, where I will start it, it will rev up some, then the rpm's will drop so low, that the engine will die. Of course, it won't throw a code or anything in the computer so that Infiniti can figure out what is going on.

My car did have something go wrong with the VVEL system- a relay or something that had to be replaced about 4K ago.

One day, at my office, after I had gotten back from a meeting, I went out to the car to go somewhere (home I think), and started it up, and 6 times it died, no codes in the computer at all. On the 7th start, it fired up and I was able to drive it home.

ALL maintanence on this car has been done at Infiniti, since day 1. This car has also had premium fuel in it every tank (Most of those tanks of gas being ethanol free premium), so it's not that I haven't been taking care of the car.

All the times I've had it at Infiniti and complained, they can't seem to come up with anything. At least I still have 2.5 more years of warranty on it.

Any suggestions, besides getting a different car? (In the process of buying a home right now, so a different car is completely out of the question!)

 

I have noticed for a little while now that when I am driving about 30 to 35 mph when I am in 5th or 6th gear that my rpms will drop well below 1000 rpm while I am driving the throttle response when I pressed the gas when this happens is pretty much like being in neutral because it revs up very high very quickly. It's very weird, and I think it is different than your issue here but there could be some similarity but I'm not sure. I have also noticed that when I going down a hill at relatively the same speed and have the car in 4th gear that the rpms drop very low and it is hard to tell the car is even on, it's almost like the engine cuts power or doesn't have any power, as the car is extremely quiet, once i get to the bottom of the hill i'll notice the rpms pick back up the engine noise and engine power pick back up also, it's very very strange, but again i think a different issue than a rough idle at stop lights, I haven't had anything like that

 

Had the same issue with my 300zx. Even got so bad that it was stalling out at lights. Never got it figured out. it happened at random intervals.

 

Having this issue on my 2010 sedan. After coming to a complete stop(usually a moderate to hard stop) the rpm will drop below 500, the car will shutter slightly, then the rpms will return to normal idle. Also does this when i initially engage the a/c. Took it to the dealer and they updated my ecu but the problem was still there. So i took it to the dealer and had the Throttle bodies and the Fuel System cleaned yet it the problem is still there. Car is well maintained and I've only used Shell 93 octane since I purchased the car. My car has 41K miles on it. Any suggestions.

 

having the same issues here. I have the stillen gen 3's, but I can remember having this problem since day 1. I have an 09 with 50k miles.

 

Not sure if this is going to help or not but found this on driver.

Idle dips very low (stalls at times) only at warm startup... - G35Driver

"quote: reset idle and accelerator position, the instructions are somewhere on the forum. Same thing happened to me, 10 minute fix."

Probably need to check that out too.