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-   -   Want to do Compression check (https://www.miataturbo.net/general-miata-chat-9/want-do-compression-check-10941/)

Rage_Kage 07-01-2007 02:15 PM

Want to do Compression check
 
I was wanting to do a compression check and I was wondering what the best way to disable the ignition is?

Trent 07-01-2007 05:46 PM

What I would do is pull the two harnesses off of the CAS.

cjernigan 07-01-2007 05:48 PM

The cas only has one harness that i know of.

Pull the connectors off the coils and pull the fuel injection fuse in the fusebox. Hold the throttle to the floor.

Braineack 07-01-2007 10:17 PM

I just pull the wires for the injector harness and coils.

Uncle Arthur 07-02-2007 09:25 AM

unplug the cas

Fergus 07-04-2007 09:00 PM

Can somebody please explain to me what the heck is goin on here ?
I thought that you'd need some type of measuring equipment to do a compression check ?

reddroptop 07-04-2007 10:07 PM


Originally Posted by Fergus (Post 128754)
Can somebody please explain to me what the heck is goin on here ?
I thought that you'd need some type of measuring equipment to do a compression check ?

Yes, A compression tester. However to use the compression tester you need to crank the engine, you don't want fuel and spark when you are cranking it just to test compression.

Everyone above is describing ways to cut fuel and spark.

Braineack 07-04-2007 10:24 PM


Originally Posted by Fergus (Post 128754)
Can somebody please explain to me what the heck is goin on here ?
I thought that you'd need some type of measuring equipment to do a compression check ?

yeah it's a pressure gauge, thats about it.

you stick it in the spark plug hole and you crank the engine...this measures how much compression you are making in each cylinder.

Fergus 07-05-2007 04:42 PM

Ah cool.
Thanks for that 8)

jayc72 07-05-2007 04:47 PM

Pull the fuel injection relay and crank away.

lazzer408 07-05-2007 04:54 PM


Originally Posted by Uncle Arthur (Post 128032)
unplug the cas

Correct.

lazzer408 07-05-2007 04:55 PM


Originally Posted by jayc72 (Post 128961)
Pull the fuel injection relay and crank away.

Incorrect. Not with a wasted spark ignition system unless you ground the plug wire you removed. If you don't you have 30,000volts that has to go somewhere and it can ark inside the coil internally and blow an ignitor.

MotorManiac 07-05-2007 05:09 PM

pull fuel fuse and remove wires. good to go :)

blue89turbo 07-08-2007 10:32 PM


Originally Posted by jayc72 (Post 128961)
Pull the fuel injection relay and crank away.

That's what I did and it worked fine for me!

Now I am tearing her down for a head rebuild


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