What sensor reads Rpm and sends it to the computer? Freescan read the when my car is turned off it is turning 50rpm yet when i try to crank it rpms come up to 125 ( i faild to mention my car will not start) what sensor sends this signal? does it come from the opti? I have not troble codes and no spark.

 

it comes from the opti

 

The low and high resolution signals from the Opti are sent to the PCM and turned into a crank position and RPM signal.

Do you have spark? How about fuel pressure?

 

so if i am getting an rpm signal the opiti is working? it it has no code?

 

i got it running my damn accel 300+ box died funny thing is i was just telling some folks how happy i was with it. o well it was 6 or 7 years old that probbaly a good live span for one.

 

thank you for your help it you replied.

 

On all LT1/LT4 engines, the computer uses the signals from the Opti-Spark to determine engine position and rpm in order to know when to fire the plugs and fire the injectors.

If your vehicle has a tach filter (early LT1), the rpm signal for the tach and ASR comes from the coil, not the Opti-Spark signals.

The later LT1/LT4 engines create a dedicated tach signal in the ECM, which is derived from the Opti-Spark signals, and sends it to the tach and ASR.

Tom Piper