Hi, I was driving my Max the other day. Then the car's RPM starts to swing up and down, and the car is like go and stop and go and stop.

What could be the problem? Some people told me it could be spark plug get clogged, some people told me I have to change my O2 sensor, and some people even told me I had hydro lock since I am using place racing style CAI.

I don't think it's the transmission, since every time when I start my car, it goes smooth for like 5 mins, then the problem starts rising. Expert please help me. I just towed my car home.

 

hydrolock? lmao. first thing you do is open up your radiator and make sure there is coolant in there. this only happens when the car is warm right? either the coolant temp switch is bad or you have an air bubble. best thing to do is check for the air bubble first. make sure the rad is filled and make sure you have some in the resevoir.

 

The radiator and reservoir are both full. Since I just fixed my water pump eariler on.

My max starts getting all the problem at 170k, and its pain on the neck for me. Spent quite some money on it.

 

did you just check the radiator or are you saying that becuase you recently fixed the water pump? If there is no air in the system, my first guess would be the engien coolant temp sensor.

 

Why are you linking coolant system with the knocking of the engine?

How does the coolany level affect the swiniging of the RPM?

And my car really hesitates when the RPM swings.

 

Check your TPS (Throttle Position Sensor - attached to the Throttle Body at the back end of the air intake/MAF). I had a similiar issue that I first thought was tranny related.

Here is my thread: http://forums.maxima.org/showthread.php?t=503300

 

Thanks. I will try to look into that.
Thanks.

 

because running a hot car while the ECU thinks it is cold will cause the engine to limit. and since you just changed the water pump there is a chance that you may have left air in the system as about 2 other people did in other posts. but its your vehicle. good luck.