Hi Eric,
I totally agree. A nuisance that (at times) really drives me nuts!


Speaking of... here's the latest update folks:

UPDATE:
I just spoke with the service manager this morning (10-15-19) at the Infiniti dealer. He told me that you cannot adjust the idle and that it is set and controlled via ECM. I told him that I thought the Nissan CONSULT III can adjust and program the idle. He said no, that is not true. I’m not sure I agree. I will contact other Infiniti and Nissan dealers and ask this question. If anything can be re-programmed on these nowadays, one aspect should definitely be the base idle. It’s all software these days as the physical ECM is hardware. I asked him then if 500 rpm in Drive (D) is abnormal, he said no.

Anyway, I then explained the whole vibration situation again and he really did not have any explanations as to what it could be. Honestly, he really didn’t seem to give a crap. He offered no solutions and didn’t even ask if I wanted to have them look at the car again to check other possibilities (the typical characteristics of a dealer). I even added that there are a lot of other owners out there that experience the EXACT same issue. I advised that since my car was re-flashed, this should eliminate any electronic or sensor issues. I said other than the ECM itself getting or going bad, the only other explanation is something mechanical underneath the car and/or with the engine/transmission. I did say that other than this vibration issue, the car otherwise drives very nice. It’s smooth, powerful and handles very well. I said I did have the underside checked (i.e. mounts, etc.) but maybe something was missed. He then said regarding the mounts, that even though engine and tranny mounts can look visually fine, he said over time they are not going to absorb as well as they did when brand new. He said that even though the mounts are doing their job, he said perhaps they could be getting weak to a point where you are feeling this vibration. I told him I would check on this in more detail and thanked him for calling me back. As I mentioned, the only hint of shining light of this dealer experience was the service adviser, Shauna. She at least gave a crap about the concern.

Now, as for the engine/tranny mounts… Keep in mind my car is only 4 years old! I doubt the mounts are the issue—unless there is a defect of some kind? The guys out there with 100k miles (and over); are they having these vibration issues as well? Probably not. Man, this is getting frustrating. Like I said, my next step is to contact other dealers for confirmation. If, in fact, the service manager is correct, then I am back to square-one. Here is a video I found several weeks ago on YouTube where they are adjusting idle using a Nissan ScanData II:


It even specifies 350Z, G35, Maxima, etc. Now, even though this video shows idle adjustment, can it save a new idle setting? If the service manager was lying, why? Of course he’s lying. In my previous update, Adviser Shauna said that per the service manager, they would not adjust idle due to it conflicting with the warranty. If idle can’t be adjusted anyway, why say that?

Ugh…

 

Called a different Infiniti dealer, and, a Nissan dealer this afternoon. Both dealers say you cannot adjust idle as it's programmed at the factory and controlled via ECM.

So, if that is the case, how are they adjusting the idle on this 2005 FX35 using a G-Scan?

 

UPDATE:
In addition to this website, I have this concern posted on infinitihelp.com as well. A member there had suggested another idle relearn and throttle position re-learn. I advised I already did that several times. The conversation got me thinking about what I have done thus far, as well as what was diagnosed and done at the dealer. Below is what I had posted on the other site just now and I am adding it here in-case anyone else has any thought or comments on this.

My car’s idle is at 650 rpm per spec when in Park (P), Neutral (N) and Reverse (R). It's only when I'm in Drive (D) and at a stop sign or stoplight (foot on brake) that the rpm is at 500 and the vibration occurs. Also, the idle is smooth too (no roughness or flutter).

Now, let me say this as this may be an important clue:
When I had the re-flash done, and as I was leaving the dealer and approached the first stop light, the rpm did go to 500, but there was NO vibration. It was like that for the rest of that day, and maybe the next day or two afterwards. As time went on, the vibration came back as it was before the re-flash.

Another piece of important info to add:
Before the technician performed the re-flash, the service adviser mentioned that the technician had found that one of the throttle bodies was sticky. She used the exact term "sticky." I'm not sure if sticky meant "glitchy" or if it was physically dirty. I'm thinking she meant "glitchy" as the TB's were cleaned about a week prior to going to the dealer for the re-flash (And yes, all re-learns were performed after the TB’s were cleaned). I’m wondering if the re-flash reset and corrected the "sticky" TB, causing everything to perform as it should. I'm curious then... since this engine has twin TB's, if both TB's aren't working perfectly in unison, could that possibly be causing an air intake imbalance at idle? Hence, causing the vibration? The only reason I mention this is due to the fact the vibration was gone after leaving the dealership—and idle was at 500.

 

Great insight!

I wonder if one (or both) throttle bodies stick closed preventing the ECM from opening to modify the idle speed? That could make sense as I often find that after spirited driving my car idles at 650 in drive.

However, my counter argument would be this scenario should also impact the car in reverse and it doesn't.

Also - I don't know if the engine idles rough when it's at 500 or if we're feeling the load on the engine causing it to "chug" (for lack of a better word) which goes away as the RPMs increase. I have a video on YouTube where my car is in drive at 500 (e brake on and blocked) with a glass of water sitting on top of the engine showing the rough idle.

-Eric

 

Hi Eric,
Yes, that's a good point. If there was an imbalance between the TB's, it should do it in Park and Neutral as well. That's a cool test with the glass of water. What would be another cool test is if you had clear intake hoses that you could visually see the TB's while the engine was running to see where each TB plate is located.

 

I have another thought and I’ll state upfront that I’m not a service tech.

We know the vehicles that experience this issue idle at spec in park/neutral as well as reverse. To me, this would indicate the throttle body is acting correctly and the ECM is able to adjust the idle speed according to variables such as altitude, air temperature, engine temperature and engine load (a/c compressor, cooling fans, etc.). This would also indicate throttle re-learns have no impact as the system is working as designed.

Which leads me away from throttle bodies, vacuum leaks, etc. Does the vehicle know when it’s in gear (drive or reverse)? Is it programmed to modify the idle ensuring it stays around 650 when in drive or reverse? Assuming the ECM knows the vehicle is in gear, what triggers this? Console gear selector? Switch on transmission? Does the PCM (or BCM) relay this information to the ECM?

Assuming the above is true (ECM knows when in gear), is it possible the trigger (switch or other communication) intermittently fails? It seems as though some are indicating that when the A/C is engaged, the vehicle is more likely to idle correctly in drive possibly indicating the ECM isn’t always aware the vehicle is in drive. Also – mine seems to always idle correctly after an extended trip or spirited drive, which in both scenarios the powertrain is thoroughly warmed up, whereas after shorter trips the engine is warm but the transmission isn’t, which might be of interest if a switch in the transmission indicates the vehicle is in Drive. One way to test this scenario would be to remove the trigger for Reverse to see if the idle speed then drops to 500 in Reverse as well as Drive.

Thoughts?

-Eric

 

Mounts can go bad easily since stock are filled with fluid

 

I'm sure you're right! From your experience, do they leak like the differential?

What we're trying to determine is why the RPMs don't always stay at 650 in drive which makes the engine idle more noticeable - when it does idle correctly at 650 it's fairly smooth. Do you know how the ECM knows when the vehicle is in gear?

-Eric

 

How can we determine if bullet #5 is working correctly?
-Eric

 

Hi Eric,
See above my thoughts on bold.

I would think too that since everything is controlled/monitored by the ECM, if, after all the diagnostics are done and nothing is wrong, is he problem then inherently the ECM itself?

Btw, the service manager I spoke with regarding idle adjustment is full of crap. The CONSULT III can in fact adjust idle. Nissan doesn't like doing this due to emissions nd EPA crap (stuff I couldn't care less about to this extent). Raising the idle 50-100 rpm isn't going to do squat to the environment. I was able to chat with an Infiniti tech from the midwest and he advised this can be done. Also, keep in mine I am not asking them to go beyond what is specified in the friggin service manual. Spec is 600-700 and I want to see a) where my base idle currently is set at, and b) tell them to increase the idle too see if it even removes this vibration.

 

If I can find a dealer that will do it. These service advisers even question WHY I want the idle checked (when I ask about setting up an appt). It's like a conspiracy or something!

Also, I've noticed lately that when I'm at a stop, and the vibration is worse than normal (i.e you can feel it in the steering wheel too) after about 30 seconds or so at a stop, the idle will increase on its own to around 650--or at least that's what I'm guessing per the location on the tach. My guess is that in this times where the vibration is really bad, I bet the idle is dropping below 500. This is the first I've noticed this, and it has occurred several times. The only thing that has changed over the last several months is the WEATHER. It's been been getting cooler lately due to fall. Since I've only had this car 3 months, it'll be interesting to see if cold temps alters anything further? I'm in Pennsylvania btw, so our winters are cold, but not Minnesota cold.

 

UPDATE:
I was browsing the Q40 Service Manual this weekend and found the Work Support section for the Consult 3. It's located in the Engine Control (EC) chapter. On page EC-145, you can see there is a selection for adjusting idle (see attached or below)

So, that means the service manager at my local Infiniti dealer (Faulkner Infiniti of Mechanicsburg) was absolutely feeding me a bunch of crap. Or, he didn't know you can do this. My guess is the former...

Last night, I decided to do an idle relearn. Except this time, I did it with A/C and radio ON. I figured it was worth a shot. Anyway, it didn't change anything.

Still scoping out a dealer that can (will) do this idle adjustment. Anyone else having any luck with anything? Anyone take there G/Q to the dealer and have then do this?

 

Thanks - interested to see how it pans out.

Nothing different here. - I'm trying to determine how the ECM knows the car is going into Drive as I want to flush out lack of communication as outlined in the FSM I posted.

Side note - low 60s here yesterday and the entire time I ran errands, approximately 2 hours with 3 stops - idle was spot on in drive.

-Eric

 

Interesting. Does it seem like your vibration issue is intermittent? Have you done anything different since the last time it was acting up? Mine is always at 500 when I come to a stop. The only time is rises to (I assume 650) is if I'm at an extended traffic light and the vibration gets really bad. I assume those times is when idle drops below 500.

 

Mine has always been intermittent and I believe that's common. There's really no rhyme or reason to why it's sometimes 500 and sometimes 650 in drive, however after a spirited drive or when the engine/transmission is thoroughly warm, it's at 650 more than not.

This leads me to believe some sort of communication error.

-Eric