My G seems to vibrate excessively at idle. More so when in neutral - rpms are around 600-700 in Park, 5-6 in Drive - A?C makes is even worse. Seems to be really excessive for this kind of car, and I don't recall it vibrating like this when new. Had a Mobil-1 full synth oil change at the dealer at 3k, car is now at 4k. I don't recall it doing this prior to the oil change, but I am not sure and I don't want to point fingers at something which may have nothing to do with the issue.

Is this normal?

 

does your idle drop or fluctuate in any way or is it 100% stable?

 

My car does the same thing, and its annoyong. It does't stay stable it dropes the rpm then vibrates then it returns normal again.
Could it be the oil?

 

xo4ox, please take a look at this thread>>

http://g35driver.com/forums/v36-engi...-rpm-drop.html

Thanks.

 

I think my startup and P is normal, but I have nothing to compare to - cold start, P, rpms jump to 1200, then slowly drop down to 6-7 or even 800 rpm, and then they basically sit there. Usually around 800 RPM in Park. And the car vibrates noticeably. Steering wheel vibrates, my seat vibrates - I mean, my G8 GT didn't vibrate this much, and it had 6 liter v-8 with a lopey cam. If I were to put a coffee cup or a coke bottle on the steering wheel, you would see a lot of wave action.

 

I read that thread on driver, guys saying he cleaned the throttle bodies and it worked like a charm

 

I also experience the rpm dropping then going back to normal. This generally happen after coming to a complete stop and seems a bit weird, almost like its about to stall.

I wouldn't consider the vibration that i have to be excessive being that i have HFC installed, but i can definitely feel when the rpm drops (almost no vibration at all).

The only changes thats been done to the car is K&N air filter, Berk HFC, and also had the TSB applied for rough downshift.

 

Thanks Q8y! It seems the throttle body cleaning is the solution. Man it sucks they voided your warranty because of your mods, it's unfair!

 

NP. yeah, and whats more ****ed up is the fact that the mechanic who tested the car agreed that the intakes (the reason why my warranty went down the drain) is not the cause for the issue. Yet the know-it-all physics genius Mr. Service Manager didn't like the mechanics conclusion and decided he was right. FTS.

 

I would go to talk to someone high up! They shouldn't void your warranty unless they can prove that the mod caused the problem, and in this case the intake did not cause it.

 

Well, apparently it's company policy to void the warranty whenever they spot an intake / HFC / etc installed. Even if you're just coming in for an oil change. Either way I don't care what they do since I'm changing my oil myself. More money in my pocket and none for them

 

Could it be oil related? It could be in that the VVEL is "sensitive" to oil pressure
AND/OR the "throttle function" on the VVEL engine is actuated up and down by
oil pressure filling and draining in a "vane" driven "motor" in the VVEL...sorry for
the vague explaination so I've included this explaination from a published
evaluation of the VQ37.....

" CVTC is integrated into the intake cam sprocket. It consists of a vane equipped inner rotor attached to the intake cam which is free to rotate within a housing machined into the intake cam gear. A pulse width modulated solenoid controlled by the engines ECU meters pressurized oil from the engines oil pump to the vaned chamber in the gear. As oil is let into the chamber, it moves the vanes with the engines rotation and advances the cam. When the ECU wants to retard the cam, it meters the oil draining out of the chamber allowing the cam to retard. By metering the inlet and outlet oil flow, the advance and retard of the intake cams can be controlled in a stepless manor.
The CVTC system has a comand authority of 37 degrees and the mechanical capabilty to move 39 degrees on the older versions of the VQ engine. The VQ37VHR has a larger control range. The unique VVEL system completely controls the intake valves opening and closing events. The VVEL system is exceedingly complicated using two separate rotating shafts driving links that operate eccentrics activating a valve activating reciprocating rocker arm that takes the place of the traditional cam lobe. The rocker slides back and forth on the valves conventional cam follower to open and close the valves. The rocker is equipped with a moving fulcrum which can quickly change the motion ratio of the eccentric to the rocker. The fulcrum position is controlled by a powerful stepper motor controlled by the VVEL computer. This Rube Goldberg-like system of linkages and shafts gives the ability to steplessly change the duration and lift of the intake valves quickly on the fly. The command authority of the VVEL system is great enough so controlling valve opening is the primary means of throttling the VQ37VHR’s output, instead of traditional throttle plates"

In a nutshell, the advance and retard of the VVEL is activated by
monitoring oil flow..this is the heart of why oil selection is so
critical to response and proper lubrication of this engine. Understanding
how the VVEL works leaves no doubt that this engine is going to be more responsive and run better on some oils than others.

I'm not claiming oil as a cause for your engines vibrating because it's
"hunting" for the correct idle speed and F/A mixture, but the VQ37 has had
well documented issues with this.......Some people have had symptoms of
noise in the valve train, and others have not had the noise, but have
needed to have the sensor and actuator replaced. In the cases I've
read about, Infiniti starts by reprogramming the ECU and refilling with
their ester oil according to the TSB.

I would start by insuring that the TSB on the ECU has been done and then
having the dealer check the sensor and actuator in the VVEL. Don't be
suprised if your service manager doesn't know about this, as Infiniti
has done a poor job training them on these issues and it seems there
is more information in magazines and the internet than is available
from the dealers.

Also, (don't shoot me for saying this), What you guys are calling the "throttle body"
on the VQ37 is a complex part of the "throttle system" and the emission control
system and modifying it will void your warranty.

 

IS the ECU TSB on this site somewhere? I'll be doing Ester / nano oil next time around.

 

I

--------------------------------------------------------------------------------
ITB08-028a - noise from bank 2VVEL Actuator

It's on "infinitihelp.com" under TSB's.....hint...if you tell the dealer
your problem and include that you occasionally hear strange
ticking noises, I'll bet you get a free oil change....but I'm not
advocating not being honest. Read the TSB for further info.
There are more and more owners reporting great results and
performance by using full ester oils like Redline, Motul, and Eneos.
My opinion is we're starting to see why Nissan recommends
ester oil for these engines. Goodluck.

 

Thanks..any performance downgrades with the ECU reflash? I looked at the ECU threads, but nothing jumped out. I guess in the end I just need to take it in to the dealer and have them look at it. Hate to do that. 90 miles away.