The graphs are made by a Mac program called "plot". You can use any "strip chart" or graphing program.
Most graphing programs will require the #Start time line to be deleted - it confuses them.

Generally it is better to look at fewer PIDs, resulting in more samples from each one.
I would focus on:
• Engine RPM
• Vehicle speed
• Calculated load value (estimates % of peak engine torque)
• Control module voltage (allow us to check alternator load)
• Absolute load value (engine load based on MAF air flow)
• Absolute throttle position & Absolute Throttle position B (bank1 / bank2)
• Short term fuel trim / long tern fuel trim for bank 1 and bank 2
• O2 sensor lambda (Bank 1, Sensor 1) and (Bank 2, Sensor 1) (under light to mid engine load should be around 1.0, which equals about 14.7:1 air/fuel ratio)

and optionally:
• Evap system vapor pressure (this will increase when the charcoal canister is being purged and can change the fuel trims and idle slightly)

My hope is that there will be a correlation between the reported engine load, absolute throttle position and engine RPM.
However, even if we do see that, we might not be able to determine what is increasing the engine load...

BUT you don't know until you look.

PS I don't have time now to look at your latest CSV log, I need to get back to work.

 

In my opinion, there simply isn't enough data to answer the question of: Why does this occur in some G's, but not others? I wish I knew the answer myself! I even asked the opposite question here on the forum: What G37 owners are NOT having a vibration in Drive (D) while at a stop? I did get a few replies, however, even on these forums, there is not enough of a sample response to get a board idea of whether or not there exists a widespread problem. I think for this particular issue, it comes down to People. I know of some people that would never notice this vibration. Yet others (all of us) that have noticed this rather quickly. I think there are tons of folks out there who probably drive around in their G’s with the same exact issue and assume it’s totally normal. Or, perhaps these people never notice anything to begin with? That being said, it appears the “vibration in Drive (D) at a stop” is a Nissan issue; not just something specific to the G’s.

Check out the two links below from the Nissan Frontier forum. Both indicate a vibration in D while stopped. One guy had the idle increased and it resolved the issue. Another guy later posted the notion that the reason the idle is low is that it all comes down to emissions and fuel economy. I would tend to believe this to a certain degree. I can see any manufacturer doing what they had to do to get there vehicle models through the general emissions threshold imposed by government bureaucrats.

#1
https://www.clubfrontier.org/threads...t-idle.228073/


#2
https://www.clubfrontier.org/threads...n-drive.54200/


These posts too seem to indicate the same dumbfounded reluctance of the dealer to have any knowledge of being able to adjust idle. As for price, I think it can be done cheaper than $220. The diagnostic fee at my dealer (Faulker Nissan) is $95. I think if you can explain to them the common reports of this issue (across several models) as well as the common solution that other Nissan dealers have taken to solve the problem (i.e. adjust idle) you shouldn’t have any problems. However, if any of them (i.e. service advisers, service managers) tell you otherwise, ask to speak directly with a master technician. Also, take a copy of the page of your respective service manual where it explains this. The evidence is there! For my service manual (Q40) it was on page EC-145 (Engine Control Section). It outlines the functions under the Work Support section on the Consult 3 software. Also, keep in mind too that adjusting the idle is still staying within specs... 650 (+/- 50).

Keep us posted if any of you guys get this done… And, be sure to share your dealership experience!

 

I, too, have a low idle (~500 rpm) in "D".

Absolute throttle position in "P" is 1.6 %.
When I select "R", the absolute throttle position increases to 2.3 % or thereabouts, and idle speed is within spec.
When I select "D", the absolute throttle position remains at 1.6 %, and idle speed drops to 500 rpm.

 

Are you using OBD Fusion or Torque?
Are you logging or did you create a sensor on a dashboard? If logging - are you able to log which gear you're in?

Thanks!
-Eric

 

You make great points!

My thought from the beginning is the rough idle is a side effect of the low idle. If you asked G owners to pay attention to where their vehicle idles in drive over a week you may get different results with many more agreeing it's sometimes at 500 and others at 650. Many drivers don't pay attention to how their vehicle idles (unless something's really out of spec) and if they have kids in the car, a chatty spouse, are on the phone or have subs installed they may not notice it. Even though we're referring to the idle as "rough" it really isn't bad and my wife doesn't even notice it (or she doesn't want me to spend money fixing it).

Coming from Lexus and Honda/Acura vehicles, I'm not used to an inconsistent idle once the engine is warm. Referencing the Frontier forum, their experience seems to be their vehicles always idle low with the resolution being to increase the idle speed. What gets me with this scenario is that the experience is inconsistent - some days it's 500 in drive, others its 650. In my opinion, something isn't reading or reporting correctly - it should always be the same idle (+/- couple dozen RPMs based on load, fans, etc.) and I have times where it's consistently spot on 500 (on the dial - not from PIDs) and others where it's consistently at 650 (again on the dial, and at least where it is in park/neutral/reverse if not 650). And - why is reverse different than drive when it's acting up?

This may remain one of the unsolved mysteries of the G series. :-)

-Eric

 

Hi. I'm using BlueDriver

I'm watching the PIDs live on a dashboard, and it logs simultaneously in the background. I do not have access to data from the TCU.

Long story short, the ECU cracks open the throttles a bit when I shift into "R", but does nothing when I shift into "D". I'm assuming this is why the idle is so low in "D".

 

Thank you!

If you scroll back to my post #105 the service manual indicates the ECM adjusts fuel when shifting into Drive for better performance. What isn't clear is what its designed to do, i.e. increase fuel, change fuel ratio, adjust throttle, etc.

I'd be curious if you see the ECM open the throttle when your vehicle is idling correctly, assuming it does from time to time.

-Eric

 

I'll see if I can catch it when it's idling within spec in "D". My hunch is it'll behave the same as when "R" is selected (a slight opening of the throttles).

 

Yeah, you would think low idle = rough idle. However, in my case, the idle was low, but smooth. My 2002 and 2016 Maxima never had any idle issues. They were always at the same idle and always smooth. We also have a 2014 Honda Pilot and it is as smooth as silk too. HOWEVER, what I noticed about all of them is that their idle was never at 500. Even my Q40, now with idle at 700 was still at or below what all the aforementioned vehicles were set at. They all have comparable V6 engines too. I'm driving my dad's Lexus RX-350 today as my Q is getting new pads/rotors. I took notice to the idle in Drive and it was at 800/850. It was spot-on and smooth as silk. In all honesty, the last time I had to deal with idle issues, it was on my 1987 Mazda RX-7 Turbo II. Wow, that takes me back. :-)

Since you are reporting your idle fluctuates (sometimes 500, other times 650 after a spirited drive) you may have another issue going on. I can say that I may have gotten a fluctuation to two before the adjustment (i.e. when at a stop for a while, the idle would raise to around 650 or so). However, thus far, I get no fluctuations post-adjustment. And, the idle stays consistent in every gear (shift selector).

 

Just to add to the data pile. After cleaning the TBs... When I come to a stop, often idle starts at 700-650 then decreases stepwise to 535-500. It repeats this behavior at nearly every stop, until the transmission/driveline is all warmed up. It runs a steady 650 from thereon out, 700 in P and N.

 

I created a poll for insight:

https://www.myg37.com/forums/engine-...-in-drive.html

 

Is there some correlation with mileage at all? From the photos posted on here, they seem to be in the high 80k miles - low 90k mile range, just like me experiencing it around 90-91K miles

 

Mine's been doing this since I bought it in 2017 at about 68k - now at 87k and hasn't changed.

Here's my original thread
https://www.myg37.com/forums/general...-and-goes.html

 

Mine started around 70k miles , I'm at 87k miles.

 

I noticed the issue around 62k miles. However, I have not owned my G (Q40) for very long... only about 3 months.