What causes the Nissan Sunny to jerk at around 40 mph?
3 Answers
There are many possible reasons for the Nissan Sunny to jerk at around 40 mph. The specific causes are as follows: Transmission jerking or impact is often not due to internal valve body damage, but rather the accumulation of stubborn dirt and impurities inside, especially when these contaminants gather in the valve body, forming blockages that prevent effective regulation of oil pressure, leading to jerking, impact, or slippage issues. Solution: The traditional approach is to replace the transmission fluid, which may help but cannot completely resolve the issue. Disassembling and repairing the transmission is not something non-professionals should attempt. However, with advancements in technology, transmission jerking problems can now be addressed through disassembly and repair. Solution: Take the vehicle to a repair shop for professional servicing.
Experiencing noticeable jerking around 40km/h in my Nissan Sunny is quite annoying. I've previously helped friends fix many similar issues. Most cases stem from ignition system problems - enlarged spark plug gaps causing delayed ignition, resulting in intermittent power loss during engine operation. Fuel system issues are also common, like slightly clogged injectors causing uneven fuel spray (especially after using low-quality gasoline). CVT transmissions frequently exhibit this jerking sensation due to chain slippage during low-speed acceleration. Faulty sensors (e.g. crankshaft position sensor) sending incorrect data to the ECU can cause unstable control. Carbon buildup in the throttle body affecting air intake is another culprit. I recommend starting with basic checks - try cleaning or replacing spark plugs first to avoid expensive transmission repairs. Regular maintenance like avoiding overloading, timely oil changes and air filter replacements can prevent worsening problems.
My old Nissan Sunny had this issue too, always jerking uncomfortably at 40 mph. I suspect it might be due to aged spark plugs not being replaced properly, causing ignition to lag behind the RPM; or a clogged fuel filter leading to insufficient fuel pump pressure and intermittent fuel supply. The CVT transmission design is prone to jerking during low-speed gear shifts, which becomes more noticeable when the oil temperature is too high. Later, I adjusted my driving habits—gradual acceleration and braking—and the jerking reduced a bit. I took it to the repair shop to check simple components, and cleaning the fuel injectors worked well. Don’t worry, many car models have this issue. Regular maintenance with proper fuel can prevent it from worsening. When it happens, slow down and drive gently for safety.
