Hello all! I am fairly new to this forum. I purchased a 2010 m35x in April 2018 with just under 74,000 miles. I have been commuting a couple times a week to a town about 80 miles away so I have put about 14,000 miles on the vehicle since I purchased it. The car is a blast to drive and has not given me any issues other than the throttle body was dirty and needed to be cleaned and reset shortly after I purchased the car. Within the past couple weeks, I am seeing a couple odd things that I am not sure are related but could be. I was hoping others on this forum might have experienced one of the other of these problems. 1) I first notice an occasional loss in power for a split second like someone turned the key off and back on in a fraction of a second. I would call it a hiccup or stumble. It does not do it often and it happens so fast that it doesn't really affect the way the car drives other than you can notice the quick jerk. 2) The transmission on occasion when driving around town will act as if have it in manual mode. What I mean is that it acts like it has a manual transmission and doesn't coast like most automatic transmissions. If I am coming down a hill it will slow the car down like if I was downshifting it so I didn't need to use the brakes coming down a mountain hill. This is also intermittent which is frustrating from a troubleshooting perspective. Because both of these problems are not constant I feel like they are related to a sensor or something computer or electrical but I don't know enough about these cars to begin to troubleshoot the problem. Weird problems like this may be hard to find for a non-dealer. I have a Nissan dealer is 80 miles away and the Infiniti dealer is 180 miles away so I was hoping that someone on this forum may have seen this before.

I took it to the Infiniti dealership and had all of the gearbox, power steering, brake fluid, and transmission fluids changed shortly after I purchased the car.

Has anyone had a similar experience on either of these problems?

Brad

One other thing... No service lights are on.

Welcome to the forum.

For the 1st issue, how are the spark plugs looking? It's possible you're having a split second misfire, although I'd expect that to trigger a CEL. Maybe try running a can of SeaFoam through your gas and also through the intake manifold (see HowTo thread for information on that procedure)?

For the 2nd issue, do the RPMs increase when you notice this braking phenomenon?

I had thought about the spark plugs because the car does have 88,000 miles on it and they could be the originals. Since I bought the car used I do not know the history other than the stuff the previous owner had done at the dealership. As for the transmission problem... I don't notice anything odd with the RPM's just that it behaves like I have pulled the shift lever to the left and put it into manual mode. It sometimes but not always acts like it is stuck in manual mode but it is in the standard drive mode. When I let off the throttle it will slow down with the RPM's increase slightly due to engine working like a break.

The battery terminals are soft metal and tear/yield easily to the point where they dont hold tension very well. See if the battery terminals are loose and causing a brief power cut. Replacements are cheap, readily available, and easy to replace

Without seeing the 2nd issue...it almost sounds like your car is rev-matching as it's downshifting...

Thanks for the replies. I will check out the battery. I know that electrical things such as grounding issues and corrosion can cause odd stuff. The car has lots of power and has been fantastic since I purchased it. The fact that they are so random is what is irritating. Thanks for your help!

try to take note of what the tach does when it cut out. if it maintains RPM readout or drops to zero. that will also help diagnose the issue

Thanks picoman and Ilya! I will let you know what it turns out to be should I get it fixed.

Brad

I had the 'stumbling' issue on my drive to chicago last week. I was cruising along about 80, er, I mean 69mph (70mph limit) and for a split second it did what I would call a stumble, like no ignition for a 1/5 second or less. Checked for lights or anything afterwards, and nothing. Didn't happen in the next 400 miles of my trip, hasn't happened since.
Probably going to do some plugs and possibly coils?? Already ran some octane booster/cleaner through the engine.
Loving the car, just wish the heated cooled seats worked better. And wish there was a heated steering wheel.

I still have the problem occasionally. I am going to go to take it in and have the plugs replaced and have them see if there are any codes that show up on the car. With the holidays and all, I have not had much time to think about dealing with the car.

I hope all of you had a great Christmas and wish you a Happy New Year!

Brad