Ok lately when i start my car the roms shoot to around 2.5 and then it will drop to 1.5 and bounce from there to 2,000 real fast. this is really annoying and it jerks my car upon acceleration. my friends that are techs say its a bad sensor but i dont know which one. does anyone have any ideas.

 

What year Civic? Is the CEL ON?

Check whether the coolant level in both the reservoir and radiator is low, and also bleed the cooling system of possible trapped air.

Could also be an intake air or vacuum leak or a dirty IACV (or dirty FITV if you have one).

 

How do you clean the IAC? Thanks,

 

See forum DIY section.

 

dito. first thing i would do is bleed the radiator fluid. that is the typical problem, just air in the system. i believe on 96-00civics ya just take the cap off and then start up the motor and let it idle for awhile till its good and warm for awhile and then put the cap on and see how she runs after toping off the fluid any of course.

 

Make sure the throttle cable is slack, and the throttle plate fully closed when you are not stepping on the gas.