Car idles good but rpm gauge reads 9k on intitial star then drops to 5000 rpm at idle . But car idle sounds fine ?????? Any ideas? No cel new distributor relay injecters timing belt and water pump. iacv been cleaned throttle body cleaned . At lost

 

Sounds like your Vehicle Speed Sensor went out? But wouldn't that throw a CEL code?

 

What year Civic?

The speed sensor and speedometer provide vehicle speed (mph), whereas the ICM/igniter unit (in the distributor) and the tachometer provide engine speed (rpm).

The false tach readings you are experiencing may caused by a bad tachometer or ICM/igniter unit.

If the ICM/igniter unit in your distributor is new and the blue wire that goes to the tachometer is properly connected, then your tachometer is probably the problem.

 

You would know it if your engine was really spinning at 9k. The tachometer itself is probably faulty. When driving, does it just stay pinned at the highest reading?

The tach is driven from a pulse from the ICM in the distributor. There's a remote chance it is defective or not hooked up right. If you still have your oid distributor you could try switching the ICM back.

 

crank postio sensor ? i already rep;ace siributor once because of this now again .

 

Check the blue wire connection to the ICM/igniter. If it is fine, the tach on the dash is probably bad. If you have a 96-00 Civic (OBDII), then you can connect a scan tool to see whether tach readings on the scan tool are normal unlike tach readings on the dash.