do you guys know if the tach will still read the crank angle sensor with the egi fuse pulled?

im doing a compression test and my readings are 7.5, 7.5, 0.0. the rpm on the compression gauge shows 999. also it does the same thing on both rotors. when i crank the car, the tach dosnt bounce. it acts like its not counting the revolutions. do you know how to check for bad sensors or what the problem might be.

 

Usually, when you yank the EGI fuse, that kills power to the ECU. If the ECU has no power, it cannot sense (or more accurately "fire the trailing coil") the engine RPM speed.


-Ted

 

i dont want to fire the th trailing, and i need to yank the egi to d the compression test. does anyone know where the compression tester ges its rpm reading from. andwhat does 7.5, 7.5, 0.0 mea on an engine.

ben

 

You could always kill the fuel pump a number of ways.

7.5 7.5 0 means a bad engine - usually dead side seal.


-Ted

 

ha ha i found the problem, the engine wasnt cranking fast enough for the compression tester to do the test and thats why it showed 999 as rpm.
the comression test counts the pulses and then makes a calculation.

engine is good now

 

That's a good ending!


-Ted