s14 ka24de having problem with idle and CEL, please help!

[csw1986]

Hi guys, I've searched but I couldn't find anyone has symptoms like mine.

My car is 98 ka24de 120,000kms. Recently, the car had 5spd swap. After swap, CEL was on because shop forgot to change the ecu to manual one.However, after they changed it to 97 manual ecu, CEL was still on. They manually checked the code and they said it was code 77 which is rear o2 sensor. So I bought it and got it installed. But after that, CEL was now flashing. (it was stayed on before) So we thought it would be the mechanic forgot to turn the knob on the ecu to back position. Mechanic did even check the code for flashing CEL but there was no code showing, and I even plugged the OBD2 and still no failure code..

Sometimes it doesn't flash, just stay on, but most time it flashes... What would be the cause??..

And one more weird thing,. When I'm driving and if I release the gas pedal, the rpm goes down to almost 400 rpm and up to 1500 rpm. Then it slowly goes down to normal idle. It happens only when under load(while driving).

Can anyone help me out?

Thanks for reading!!

[csw1986]

Anybody?~

[rogoman]

A flashing CEL is caused by a misfire. One or more DTC codes P0300 to P0304 are most likely set. A misfire could be caused by bad spark plugs or by dirty fuel injectors.

[csw1986]

I already changed the spark plugs.

And like I said, there is no failure code, but cel is still flashing