What is the problem with 4000 RPM at 100 km/h?
3 Answers
4000 RPM at 100 km/h indicates slight clutch slippage. Here are detailed explanations about clutch slippage: Manifestations: Clutch slippage mainly manifests as the vehicle's speed failing to increase with the engine's RPM during acceleration, resulting in the engine's power not being fully transmitted to the drive wheels, leading to weak driving performance, especially noticeable when going uphill. Causes: The main causes of clutch slippage include insufficient friction of the clutch friction plate; shifting gears too early or disengaging gears before the clutch is fully engaged; prolonged driving with the clutch partially engaged or coasting with the clutch pedal depressed; shifting or disengaging gears incompletely, and abruptly applying throttle when the gear is not fully engaged or disengaged, causing abnormal wear of the clutch plate.
Oh, I just encountered this issue the other day! When the speed reached 100 km/h, the RPM surged to 4000, making the engine roar. I figured it's mainly because the transmission didn't shift to a higher gear. For automatic cars, it might be due to dirty transmission fluid blocking the shift, while for manual cars, it's probably forgetting to shift to fifth gear. Sometimes, climbing steep slopes or carrying too much load can also cause this, as the computer automatically downshifts and revs up the RPM. If you frequently brake and accelerate, the transmission computer might get confused. Also, a throttle body dirty as coal can restrict airflow, so that needs checking. Lastly, if the drive shaft is worn out, the power loss will be significant, naturally causing the RPM to soar. This problem needs fixing ASAP, otherwise, it'll waste fuel and damage the engine.
My old car used to do the same thing, the tachometer would shoot up to 4000 rpm on the highway. Turned out the clutch was badly worn, couldn't transfer power to the wheels. If the transmission synchronizer has issues, it can get stuck in third gear like it's glued there. I've also heard that when the oxygen sensor fails, the ECU can't calculate the air-fuel ratio properly and just gives you high revs randomly. Aging ignition coils are silent killers too - weak sparks make the engine work harder. Changing transmission fluid is the cheapest fix, you can even DIY - just clean the filter first. If new fluid doesn't help, chances are you'll need a transmission teardown, and that's gonna cost big bucks.
