Idle Irregularities

[hfrez]

I started an earlier thread called "Bad Gas" which has now evolved into another question that I would like to have answered if possible.

Every time I stop at an intersection my RPM's will drop from 750 to 625 after about 15 to 20 seconds and the motor vibrates like it is starving for gas but never really stalls. I thought that I might have picked up some bad gas but I'm on my fourth tank since then and have gotten new fills from trusted gas stations. I added some STP Fuel System cleaner for Ethanol gas two tanks ago and now I added Sea Foam to try to cure the problem thinking it was bad gas. It seems to help some but it has not cured my problem at all.

So yesterday I took it to the dealer and the mechanic said that this was normal for the 4.0l and occurred also in the Titans and Armada's for some reason. However, he did sit in my truck shifting the tranny back and forth with a semi-puzzled look on his face. He went as far as telling me that I should try out someone else’s Pathfinder and that I would see they are doing the same.

Other things that I tried was taking it out of gear and putting into Neutral or Park but the engine vibration did not seize. I also turned off the A/C and that did not help either. I guess my F150 SuperCrew Lariat has pampered my behind too much but this is not what I expected from a 2011 vehicle.

So my question is does anyone else have this noticeable problem?

I have also purchased a VOLO V12 that I have not yet installed and I think it will change the fuel mapping to a higher idle which may help but I do not want to install it until I am sure that it will not just mask a problem that has a potential to get worse.

[disallow]

The only time I've noticed a blip in the RPM is when the fan clutch engages. Otherwise the idle is rock solid.

[goblue90]

Does your rpm shoot up (say, over 1000) when you initially start the vehicle?

[hfrez]

Does your rpm shoot up (say, over 1000) when you initially start the vehicle?

Oh yes. The mechanic said that this was normal as well. I see mine go to 1500RPM's and then it will slowly make its way down to 1000RPM's if you wait about 15 to 20 sec. Then for the first few miles of driving it will land and stay at about 1000RPM's at intersections or stops.

[hfrez]

The only time I've noticed a blip in the RPM is when the fan clutch engages. Otherwise the idle is rock solid.

But even then the ECM should adjust for the power loss and raise the RPM's!

[goblue90]

Does your rpm shoot up (say, over 1000) when you initially start the vehicle?

Oh yes. The mechanic said that this was normal as well. I see mine go to 1500RPM's and then it will slowly make its way down to 1000RPM's if you wait about 15 to 20 sec. Then for the first few miles of driving it will land and stay at about 1000RPM's at intersections or stops.

Did you clean your throttle body recently? I had the exact same symptoms after a shop cleaned my throttle using BG Product's Fuel/Air Induction service, which messed up the sensor on the throttle plate. I have pictures that I'll post of what it's suppose to look like vs. what happens after you run cleaner through the throttle body. I performed the following procedures well over a dozen times before I purchased a new throttle body.

1. Accelerator Pedal Released Position Learning
2. Throttle Valve Closed Position Learning
3. Idle Air Volume Learning

I installed the new TB myself, performed the Idle Air Volume learning procedure and the rough idling went away. Try doing the IAV learning procedure before replacing the TB unit. Here's a thread related to idling issues after cleaning the throttle body.

http://www.thenissanpath.com/viewtopic. ... sc&start=0

The link contains the steps to perform the procedures listed above. Good luck!

[pathology]

My '08 4.0 does this, I'll give the procedures a try, thanks!

edit: is there a throttle body cleaning procedure somewhere in here? I've looked, but not found one.

[dared3vil00]

Wait, is it not normal for the engine (on cold start) to shoot up to around 2300RPM's then back down to idling at about 1100-1250?

[aadadams]

Wait, is it not normal for the engine (on cold start) to shoot up to around 2300RPM's then back down to idling at about 1100-1250?

My 05 does it...

[JAHBLESSINGS]

my truck idle's fine and i've cleaned my throttle body/plate about 5 times or more since i've owned it. i don't spray anything into the throttle body. i spray this wynns induction spray on a shop rag and wipe away.

[hfrez]

Well I just got done installing the VP12 VOLO Performance Chip yesterday and it seems to have resolved my idling issue. It is true that the VOLO changes your fuel mapping and therefore the idle is set a bit higher. This resulted in a better gas pedal reaction. The Pathy now has a much better and smoother response on takeoff. I have to remind you that I do have a K&N FPIK cold air intake system. My previous problem could have been a result of that but the chip accounts for having it installed so that makes a big difference.

Yesterday I showed a Mustang GT driver (4.6l generation) the rear end of my truck . Blew him away until we hit 100MPH and then he passed me but it felt goooood. I was able to rev out the engine at 6250RPM's between the first two shifts. Man it feels better than my old F150 5.4L Lariat when it pulls away. (The Lariat was also modified with K&N, Gibson Exhaust & Dialo Performance Chip).

I'm too cool for school now!

[goblue90]

Wait, is it not normal for the engine (on cold start) to shoot up to around 2300RPM's then back down to idling at about 1100-1250?

Sorry, I re-read my post and realized it didn't make sense. Yes, the engine does shoot up over 2,000 rpms... I meant to write:

"Does your rpm stay high (say, over 1000) after initially starting the vehicle?"

Mine did that after the whole TB cleaning incident, and then bogged down when stopped at intersections.

Pathology, the best way to clean out your TB is how Jahblessings explained it... spray on a rag and then wipe, don't spray directly into your TB.

Hfrez, glad to read that your idling issues have been resolved.

[dared3vil00]

It only shoots up on the initial ignition process, perhaps half a second? then goes back and stays steady at at around 1000 RPM's (i watched it closer today)

[Fookn4x2]

Mine too guys. Idle will shoot up to around 2K then stay at 1100-1200 for about a minute before dipping down to 800. I usually start it then turn the wheel to drop rpms a bit so it doesnt have to shift hard into gear when backing out of my driveway. I don't like waiting a minute and a half to drive my truck. After driving a while it will do the engine vibration and dip in rpm's thing at red lights or while stopped. If anyone finds a solution let me know!