RPM dips down then jumps back up when slowing down or braking

Isn't it soot? Probably burned off gas deposits etc from the engine, not from the air.

I know cadillacs require throttle body service every 20,000 miles or something. maybe our engines just need them too, but isn't part of the service manual for some reason.
 
Had this same problem that just started to acted up a few weeks ago, just got it back from dealer they claimed they did a reprogram as I complained of rpm dipping when almost at stop (brakes on). Also did an update on transmission bc of weird the weird upshifting it was doing, got it back seemed ok will wait a few days to see if it holds. LOL
now that you guys mentioned it maybe throttle body problems it maybe a good idea on check the flapper valve on air intake duct which regulates you air into engine. Usually would build up with grit and oil which gets the valve sticky and not to move freely, I previously had similar problems with rpm problems dipping on my motorcycle that flapper would not function correctly bc of build up which mostly came from my overly oiled k&n air filter. :eek.:
 
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After the update the dealer did all is well now. It was actually scary in stop and go traffic because when I would brake or let off on the gas the RPM would dip real low then bounce back up to maintain the speed. When it did this it would cause the FX to get to the point where the engine almost cut off in the middle of driving and it kept making it jerk when it did it. Almost like a feeling that your being hit from behind.
 
I only have one more complaint but thats with the transmission software. All Infiniti's with the 7 speed auto have the TCM programmed to lock the torque converter in real low when coasting or at low speeds. When I'm coasting or driving around 35-40 mph the car revs around 1100-1200 RPM and makes the engine sound like its bogging down. I think it's annoying but apparently Infiniti says they programmed it to rev low at cruising speeds to get the best gas mileage. I'm at like 35mph and the car is like in 6-7th gear :sluggish:

Two ways to fix this though from my experience:

1. Drive in DS mode to keep the revs up and the response better

2. Or step on the gas to get the torque converter to unlock and then it responds much better. This is why sometimes when cruising and you need to take over another car and change a lane you REALLY need to step on the gas to get out of that low revving. Then all the power comes at once and it throws you back in your seat. Another way around it is to throw it in manual mode and downshift to a lower gear to overtake someone.
 
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Fire0nic3FX said:
Something I've been noticing for quite some time now is when I'm in stop and go traffic or whatever and I push the brake pedal to slow down or come to a complete stop the engine speed (RPM) dips really low for a brief second almost to the point of the engine sounding like it's going to cut off, then it RPM bounces back up to normal cruising RPM speed range. Anyone else have this problem on here? I found a bulletin, but I'm not sure it's the same thing:

ITB10042


  • IF YOU CONFIRM The customer reports any of the following: - Engine hesitation at idle or very low speeds, and/or - Engine speed drops lower than expected when decelerating or coming to a stop. ACTIONS 1. Refer to Step 2 in the Service Procedure to confirm this bulletin applies to the vehicle you are working on. 2. If this bulletin applies, reprogram the ECM. See this bulletin for further detail.
Click to expand...

I had the same exact problem. I cleaned the throttle bodies and it's been fine since.
 
We just picked up CPO 2010 FX 35, after being loyal 5 years to German cars
Let me tell you from German's cars expert - FX is an excellent car hands down , we really love this crossover
The only issue we had with it , - jerky transmission on low RPM , harsh 2-1 downshift ( as many of you probably know )
Good news, - after dealer installed bulletin ITB12 064A ( tranny software patch ) , transmission feels like a new today
Have it a try :)
 
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Is this a new Tranny patch ? I had a flash maybe a year ago regarding downshift jerking.
thanks
 
this happen to all of my and my friends new model infiniti like my g37x, my g35. the fx. and my buddys g37xs. i think it has something to do with the vacuum
 
same on my FX35 2009 since a while... ignoring it for the moment. Long time I don't clean throttle body.
 
I had same jumping revs at low rpm. I did a DIY G37 throttle body cleanup. Problem went away so far. Saved some bucks for Chritsmas [emoji3]


Sent from my iPhone
 
hey fire, how much do you think it would cost for your throttle body to get cleaned in nyc? wanna see if this will work.
 
I'm also in NYC, if you find a spot and get a quote let me know. I just picked mine up last week and also noticed weird shifting. Idk if it is because I'm coming from driving manual or not being used to this 7sp but something doesn't feel right
 
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