So I don't disable the ignition system? Or does pulling the injector fuse disable both systems?

 

noooo really?? looks like ive done that i crompresion tested and now it wont start any ideas where i can get a coil unit cheap?? thanks

 

Just the fuse is fine. When you crank the motor thats where the psiton gets the power to give you your compression.

 

just unplug the ecu

 

Here is how I have successfully did multiple compression tests.

- Remove the 10amp ecu fuse under the hood
- Unplug the distributor plugs

Remove One plug at a time and screw in the fitting for the compression gauge, Crank the engine over 8 times with the throttle open. Read the number. Reinstall spark plug, move onto next cylinder.

I've did this probably over 10 times and never blew a coil, icm, etc.

Just my .02

 

and when you do the compression test what are the numbers supposed to be? like for a 99B20b?

 

i did a compression check just yesterday and didnt pull the ecu fuse and my turnt on and then shut off a sec later , now it turn but doesnt turn on.. im thinking i blew my coil. but it was late so today im going to check my main relay and the coil .. any thing else should i consider?

 

I think Jimmy meant unplug the dizzy harness, this way no voltage ever gets to the dizzy to fry anything, in addition to the 10 fuse

 

this is how ive always done it

1. disconnect small plug on distributor or plug on coil
2. take out spark plug and screw in compression tester
3. turn motor over with wide open throttle
4. release pressure
5. move on to next cylinder
6. ect
7. ect

 

a little tip my auto teacher taught me to check if its in the top or bottom end is to place a cap full of oil into the cylinder thats being tested and if the reading goes up then its in your bottom half (rings are shot) and if it stays the same then you know its in the head.