I am having a weird problem and i was hoping maybe one of you can help diagnose the issue.

When the car is cold it runs perfect. Once its fully warmed up (about 10 minutes) i am getting this weird pulsing feeling from the motor. This pulsing starts at 1500rpm almost exactly and goes to about 2500rpm. If i give the car more throttle through this range i cannot feel it, but if i give the car light throttle then the car feels like its pulsing, not really sputtering, more like a pulse feeling of vibrations.

I know in the past i had some issues with the fuel system and it being dirty, but fuel system cleaner always resolved it. But those problems were a BAD sputtering through the whole powerband, hot or cold car. This new issue only happens after the car is warmed up.

Any suggestions on where to begin? I have no CEL codes.

thanks

 

Your description fits that of a lazy O2 sensor. I experienced a very similar situation on my '90 Civic Si. The ECU won't code a lot of times because it is still getting some input from the sensor. The problem is that input is way out of time for any useful fuel trim information.

FWIW, the generic Bosch didn't work well for me. I ended buying an OEM sensor.