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Discussion Starter #1
When at a stop/idle the RPM's jump from a base of about 1K to 1.5K and sometimes 2K. I'm assuming this is caused by the AC systems kicking in, but surprised since luxury manufacturers typically smooth these things out. It's most noticeable when the RPM jumps +500 from base which then starts to pull the vehicle forward causing me to push harder on the brakes.

I'm wondering if anyone has the problem or noticed this as well?
 

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An electronic fuel injection system is a "closed loop feedback control system". Control systems was the hardest class on my way to a degree in engineering... Anyway, the intake side has a device called an "idle air controller", or IAC. It is a servo motor that controls how much air goes into the motor when the throttle isn't being pushed. If the air was a fixed amount, like an old carburetor, it would idle at different speeds under different conditions.

When the AC comes on, the additional load pulls the motor down a titch, and then the IAC lets more air in (and injectors let more gas in) to keep the RPM the same. The control algorithms in smaller motors may be coded to raise the RPMs a little bit so the AC isn't taking such a large percentage of the available power. That's why on big V8's, you don't even notice the AC cycling.

A 3.5 liter motor is certainly capable of maintaining RPM. Are you hearing the compressor clutch with these RPM rises?

Our JX is about to arrive. Since the price went up after we ordered it, I have the option to bail out of the deal. With how buggy these cars seem, I think I am about there.
 

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An electronic fuel injection system is a "closed loop feedback control system". Control systems was the hardest class on my way to a degree in engineering... Anyway, the intake side has a device called an "idle air controller", or IAC. It is a servo motor that controls how much air goes into the motor when the throttle isn't being pushed. If the air was a fixed amount, like an old carburetor, it would idle at different speeds under different conditions.

When the AC comes on, the additional load pulls the motor down a titch, and then the IAC lets more air in (and injectors let more gas in) to keep the RPM the same. The control algorithms in smaller motors may be coded to raise the RPMs a little bit so the AC isn't taking such a large percentage of the available power. That's why on big V8's, you don't even notice the AC cycling.

A 3.5 liter motor is certainly capable of maintaining RPM. Are you hearing the compressor clutch with these RPM rises?

Our JX is about to arrive. Since the price went up after we ordered it, I have the option to bail out of the deal. With how buggy these cars seem, I think I am about there.
It's easy to assume they are buggy, but I only have one complaint about my jx and that's the acceleration. No other issues.
 

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I have the same issue with the engine revving between 1000 to 1500 rpm when idling. I will ask about it at my first service as it seems odd to me as well.
 

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Discussion Starter #5
I have the same issue with the engine revving between 1000 to 1500 rpm when idling. I will ask about it at my first service as it seems odd to me as well.
How long till you head to the shop? I'm only at 1,500 miles so it will be another 2 months. Not worth making a separate trip.
 

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It's easy to assume they are buggy, but I only have one complaint about my jx and that's the acceleration. No other issues.
Seriously? Half the threads on this forum are about problems. Infiniti is lucky they have customers who are willing to over look problems. Maybe it's hard to concede that a premium was paid, but premium value wasn't delivered(?) If a Kia had as many issues, it would get ripped to shreds on the internet. I am sure the problems will subside in time, after they have had time to do some engineering revisions. It just seems like they released these too soon. I wonder if they though the MDX was pending, and they jumped the gun.
 

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Problem Threads...

If only half the threads on this forum are about problems, that's pretty good. I see thousands of reads of some threads and only 30 or 40 problem threads. That's pretty good considering most people don't post "I'm not having any trouble!"
 

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Discussion Starter #9
If only half the threads on this forum are about problems, that's pretty good. I see thousands of reads of some threads and only 30 or 40 problem threads. That's pretty good considering most people don't post "I'm not having any trouble!"
According to Google, this is the biggest JX discussion site. The biggest threads have to do with the difference between the Pathfinder, delays in production, etc. not issues.

If you are concerned about quality, take a look at the X5, GL, Q7, Arcadia fourms on edmunds. It will scare you back to Japanese. GL discussions starts off with the cars catching fire. Page after page of X5 failures.

Of all the forms and issues on this site, I haven't seen a single catastrophic failure (tranny, engine). Not one.

My JX has small things (idle jumpy, driver side washer shoots too low), all small compared to others.

My biggest complaint is the deadbeat dealership network in DFW. Lies, deceitful service, and general lack of respect are the reasons I don't recommend Infiniti to others. Too bad it's illegal to sell cars directly to the public.
 

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I wonder if that's the cause for the jx having sudden acceleration when at a stop with the brakes on. I had instances where I'm at a stop light with my foot on the brake pedal and she just jumps a good couple of Inches forward. It scared the heck out of me while I was close to another vehicle the other day and it happened. I probably had about an inch left of distance between me and the other vehicle. Anyone?
 

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Only had two issues: back door automatically closing and a stuck SOS button. Both were resolved by the dealer. Other than that, pretty sweet ride approaching 4K miles with several weekend road trips.
 

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I had an engine revving issue. Brought it in for service today and they re-set the idling. They said that there will always be some minor revving, but mine was erratic. The re-set has corrected the problem.
 

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my engine idle jumps up and down at red lights. dealer reset but still jumps.goes as low as 500rpm stutters and jumps back u. doesnt die or anything but is annoying as hell.
 

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Discussion Starter #15
I wonder if that's the cause for the jx having sudden acceleration when at a stop with the brakes on. I had instances where I'm at a stop light with my foot on the brake pedal and she just jumps a good couple of Inches forward. It scared the heck out of me while I was close to another vehicle the other day and it happened. I probably had about an inch left of distance between me and the other vehicle. Anyone?
Was the break pushed down solid/hard or just enough to stop rolling? Mine happens when the break is lightly applied.
 
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