(2003 AUTOMATIC g35)
Hey everyone, I’m new here but I made this account because I recently ran into a problem and Idk what could be wrong. I’ve owned the car (03 auto g35 coupe) since October and it currently has 202k on the body and 150k on the motor.

(NO CEL) If I take off from a stop (full throttle almost) or if I’m at a low speed/gear then I floor it, my car bucks and I can see the RPM rev as if I’m two stepping it, and I get a really jumpy/uncomfortable acceleration. It feels like my suspensions being worn out every time it jerks. my brakes are starting to give me the warning noise as they need to be replaced soon, but I doubt that has anything to do it with it. I attached a vid so you can hear and see what my problem is. My throttle is fully depressed as this occurs.

im thinking maybe it’s the throttle body/ tb sensor, or something regarding fuel (injectors/distributor/pump/spark plugs) hopefully my ECU isn’t fried.

I have yet to check anything or look at anything specifically as my apartment complex doesn’t allow me to work on my car, so I’m just trying to get ideas, in case any of you have had the same issue, beforehand so that I don’t start messing things up trying to fix it.


(also just edited this in I noticed it happens around 3-5k RPM in first gear, or while downshifting from second into first, AND RECENTLY I discovered it happens in high rpm second gear also, so I’m assuming it’s maybe throttle fuel or torque converter related

 

 

Manual transmission? Could be clutch slipping and quickly building enough friction to grab again.

Get out on the highway in 6th gear and stomp the throttle wide open. If the tach jumps but the car doesn't accelerate to keep pace then it's definitely a worn clutch.

 

thanks, (i wish it was manual) but it's an auto, I'll put it up top so it's more clear

 

And the tires are NOT spinning correct?

What modifications if any do you have.

 

It definitely sounds like something was slipping though, my suspicion is that it's clutch related so for a 5AT that would be clutch packs on 1st gear. When was your last transmission drain/fill and what did the fluid look like?

 

I had someone drop a new motor in and he replaced all fluids about 9k miles ago(december), he didn't tell me the fluid looked dirty.
i'm going to check from the throttle body to the air filter for any cracks that could be letting in too much air as soon as the apartment complex manager leaves.

I don't think it's slipping (although it could be) because my RPM barely inches up and down, you can hear in the video how the speed increases as soon as it starts "catching". it just seems unreasonable to be a slip if it only happens that perfect moment(which made me think it was a spark plug or misfire) but it only happens in first gear it seems.
The RPM is going the same pace as the speed, but the cars lurching from 3-5k RPM. it feels like i'm driving in a manual and two stepping in first gear until it shifts

definitely going to be changing the transmission oil as a precautionary step

 

the tires(front and rear are all 225-55-r17) are spinning but not loosely. when it starts lurching i feel my tires losing power also. it spins with the RPM, so it feels like the drive train is correctly functioning in regards to the tires spinning, which makes me think it wouldn't be anything transmission related.

 

It seems like it is only when the throttle is completely open, because it doesn't happen if i'm slowly accelerating up to the next gear( from first to second, but if I accelerate in the high RPM range [3-5k] it'll become "bouncy" and the RPM will bounce up and down with the speed of the car)

 

also, I tried this last night to test that(scary as ****) and it accelerated smoothly passed 80 in 6th gear

 

right now all i could think of as possibilities is
1:my fuel pressure is just slightly too low, and first gear is the only gear demanding enough to exceed the amount of fuel available
2: throttle body isn't opening up all of the way
3: throttle body is allowing too much air in because there could be an air leak after the throttle
4:transmission is slipping in first gear at high rpm only?
5: some sort of sensor is broken or my ECM/ECU got fried somehow

 

Bump pls help lol

 

My advice at this time is take it a local Nissan dealer (cheaper than Infiniti) and pay the $150 or so for a diagnostic check. It'll tell you exactly what's wrong and what needs to be done t fix it. We can only help so much and you might wait 2-3 more days for someone to finally figure it out here.

 

Im hoping I can avoid that because I’m kind of broke right now, but if it’s comes down to it and it becomes more noticeable I’ll definitely take it to prevent anything else from breaking. Also I found out it’s heat sensitive like it doesn’t happen right after a cold start; so that leads me to believe it’s a sensor that just starts acting up when it’s either active or maybe the wires or sauters (idk how it’s spelled) which is somewhat relieving. Thanks for letting me know Nissan will be cheaper though!

 

Also if I slowly accelerate this doesn’t happen only when I’m close to flooring it. It feels as if I’m accelerating on a really bumpy road causing it to cut power with every bump and once it shifts into the next gear it goes back to normal. Also my suspension is really shitty right now so I’m wondering if anything behind the tires could be causing it like a busted strut or spring? But I wouldn’t expect it to be jumping because the suspension can’t handle the power, or if that’s even possible