im new to the forum and any forum for that matter. This seems like a good place to get some useful info. I recently purchased a 2007 g35s sedan 6mt and absolutely love it except for the fact that recently started doing this weird bucking at low speeds, typically only in gears1-3.no there are no codes no cel or any other light. clutch and trans feel fine, and the engine has plenty of power. haven't tried changing cam sensors yet. did supposed ecu reset and throttle resets with no change. I figured before I went any further id see if anyone else has experienced this, and possibly know a remedy

 

Are you sure it's engine related and not drivetrain backlash from worn differential bushings? Start with all the obvious wear items on the engine, vacuum lines, intake tract pipe leaks, spark plug and coil inspection, etc.

Perform the ECU reset, idle air recalibration, throttle position recallby doing the pedal dance.

When exactly does the issue happen in relation to clutch engagement?

 

I thought about that at first and I haven't gotten around to checking underneath like I would like to, but it seems to intermittent to be bushings or something. The shifts, the clutch, and the driveline feel smooth. 90% of the time the is no problem what so ever. Also, you don't have to use the clutch to make it happen. simply slowing to make a corner then smoothly applying throttle after will make it happen. it happens maybe 2 to 3 seconds after lightly applying throttle. also first 10 minutes or so of driving after sitting overnight its perfect

 

That sounds like differential bushings to me, if you're going about 20mph in 3rd gear and you accel/decel you probably feel it right? It's a common wear item on the vehicle, you shouldn't feel ANYTHING except the g force from excel/decel if everything is functioning properly.

This is really easy to identify as well, it's easiest using a local oil lube shop with a pit, chock the front tires, "drive" fwd / rev, just a little pressure from the clutch to apply torque to the rear diff is all you need not much, if it's an automatic just putting it in gear is probably enough.
The other person stands below the vehicle and watches for differential movement, it's obvious, you see it twist, you see the bushing compress badly one direction or another, if there is ANY play then you probably found the culprit.

If using a pit isn't an option (they always accept cash as a "diagnostic fee" wink wink) then you can pull on it by hand but it's harder to tell imo.

 

ill deffenetly check that out and let you know what find out.

 

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Just resolved this on my 2007 g35s 6mt, I'm about to make your day. So this hesitation/bucking happens after about 10 mins because after your engine reaches operating temp it starts modulating the cams. I bet You can watch on the temp gauge and the car will literally change at the same point like a switch . So it can't be any mechanical like bushings ect. The ecu isn't getting the proper readings from the sensors on the motor because the two points of connection are terrible! Seriously the #6 wire, negative, both from the battery to the frame and from the motor to the frame, is poorly connected because the surface was painted. This is the common connection for basically everything back to negative on the battery. Coil packs sensors, solenoids everything goes thought to this big wire so honestly find those two points and scrape off the paint you will have a different car. You can buy a grounding kit or basically just scrape off the paint under the connection. One point is easy one is tougher but I bet if you just did the easy one on the driver side wheel well it would prob change it or half cure it then you would know to continue. Love you too

 

That is a known issue on G35 sedan 07-08. It is related to exhaust valve timing solenoids which are in the front timing covers. Try disconnecting blue connectors under the hood just in front of your car and check. If the issue is gone, then you have to replace front timing covers.