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I read through the search (compression tests) on here and finally decided to do the compression test myself. I just have a couple of question.

1. What happens if the psi between each plug is more than 14?

2. Another thing, what does "crank/turn the engine over until guage stops responding" mean? (I know this is a stupid ?)

3. Should I give full throttle or not, whats the difference?

4. Can you check it by turning on the car for a short while, letting the guage measure the pressure, then shutting off? (my friends mechanic told me this was okay to do, but not sure)


thanks in advance
john
 
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WhiteVR4demon said:
I read through the search (compression tests) on here and finally decided to do the compression test myself. I just have a couple of question.

1. What happens if the psi between each plug is more than 14?

2. Another thing, what does "crank/turn the engine over until guage stops responding" mean? (I know this is a stupid ?)

3. Should I give full throttle or not, whats the difference?

4. Can you check it by turning on the car for a short while, letting the guage measure the pressure, then shutting off? (my friends mechanic told me this was okay to do, but not sure)


1) This means you car's power production is not balanced any more.

2) Keep cranking the engine until compression gauge stops going up, meaning it has reached highest pressure reading. Needle will jump some 50 PSI at the time.

3) Open throttle (step on gas). This allows engine to breathe, becuase if it's closed, and you run out of air in intake manifold, it'll create vacuum, and it'll be slower to fill out the combustion chamber with air.

4) Don't do that. Take out EFI1 and EFI2 relays, so the injectors don't open, and remove all plugs and coils before getting readings. If the car spray fuel into cylinders w/out burning it, it will contaminate your oil, and wash the oily film off cylinder walls....not a good thing.


Hope this helps.
 
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They are in the engine bay, behind the battery under that black plastic cover. Underside of the cover has the map of where is each relay.
 
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