Compression Test Cranking Rpm
03-28-2013, 09:37 AM
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Compression Test Cranking Rpm
Quick Question About Cranking RPM
Going to do a compression test tomorrow, just wondering if my torque app will still show engine rpm with ESS disconnected? I want to log my rpm with torque to find out my true compression numbers
Going to do a compression test tomorrow, just wondering if my torque app will still show engine rpm with ESS disconnected? I want to log my rpm with torque to find out my true compression numbers
03-28-2013, 10:19 AM
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I'm pretty sure it uses the ESS. Mazda typically grabs it from there. It would be by far the most accurate method, I think everything else would have to be derived from other factors?
03-28-2013, 10:58 AM
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Yeah I read that you disconnect the ESS when doing the compression test to stop spark and fuel but it made me wonder if I would still get the rpm signal, ill find out for sure tomorrow
If it turns out that there is no rpm signal, would I just be able to pull my fuel pump fuse and crank the engine with ESS plugged in to see my cranking rpm?
If it turns out that there is no rpm signal, would I just be able to pull my fuel pump fuse and crank the engine with ESS plugged in to see my cranking rpm?
03-28-2013, 02:20 PM
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How do I make it so I can just crank the engine without starting while the ESS is still plugged in? Just disconnect the fuel pump fuse?
03-28-2013, 02:30 PM
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So Holding the Gas Pedal down Fully while cranking kills Fuel? So I guess even when im doing the compression test I wont need to disconnect the ESS since I will be holding the gas pedal down fully
Good to know thanks
Good to know thanks
03-28-2013, 02:38 PM
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Pulling the fuel pump fuse is one way, although I'd honestly also disconnect the coils from the harness. During the test you will have 1 or more plugs that are no longer grounded, and a coil firing without a place for the current to go will fry fast. How fast? Unsure, but from other forums and other cars it can be as fast as ~10-15 minutes of firing time. Even if you are firing for less than that, no reason to put your coils through that.
Disconnecting the ESS kills both fuel and ignition WCS. The ECU needs it to know when to fire the injectors, and won't fire them without that information.
Disconnecting the ESS kills both fuel and ignition WCS. The ECU needs it to know when to fire the injectors, and won't fire them without that information.
03-28-2013, 03:15 PM
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Pulling the fuel pump fuse is one way, although I'd honestly also disconnect the coils from the harness. During the test you will have 1 or more plugs that are no longer grounded, and a coil firing without a place for the current to go will fry fast. How fast? Unsure, but from other forums and other cars it can be as fast as ~10-15 minutes of firing time. Even if you are firing for less than that, no reason to put your coils through that.
Disconnecting the ESS kills both fuel and ignition WCS. The ECU needs it to know when to fire the injectors, and won't fire them without that information.
Disconnecting the ESS kills both fuel and ignition WCS. The ECU needs it to know when to fire the injectors, and won't fire them without that information.
03-28-2013, 03:20 PM
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Pulling the fuel pump fuse is one way, although I'd honestly also disconnect the coils from the harness. During the test you will have 1 or more plugs that are no longer grounded, and a coil firing without a place for the current to go will fry fast. How fast? Unsure, but from other forums and other cars it can be as fast as ~10-15 minutes of firing time. Even if you are firing for less than that, no reason to put your coils through that.
Disconnecting the ESS kills both fuel and ignition WCS. The ECU needs it to know when to fire the injectors, and won't fire them without that information.
Disconnecting the ESS kills both fuel and ignition WCS. The ECU needs it to know when to fire the injectors, and won't fire them without that information.
I would disconnect the coils but I would have to remove the intake and tube to get at them which is more work then I want to do, 5-10 seconds worth of cranking when checking for rpm hopefully shouldn't hurt my BHR coils ;/
Last edited by DinSum; 03-28-2013 at 03:30 PM.
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