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The mkiv Supra Owners Club

How to do a compression test?


Tom
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what i do, what you do doesn't really matter. not everyones head or garage is as clean as a whistle.

 

why take the risk?

 

Very very true ...some do it this way some do it others.

 

I have noticed that the readings can be ever so slightly lower with the plugs in ..just a tad due to the restriction in the other cyls . It can be done either way you just have to work out your readings. What i will say ..is that OEM comp readings are all done on the bench with all plugs out ..but taking 3-4 psi on the reading wornt hurt. But horses for courses :thumbs:

 

And the same on google. most if not all use the plug out method ..but a few keep em in :)

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This test should be done on a HOT engine.

 

So to clarify;

Hot Engine

Fuel Pump unplugged

1 plug at a time removed..

Working battery ;)

 

A flooded engine won't start but give it time and it will again...

 

Can't you just leave the fuel pump plugged in and just remove the efi fuses as someone else said on here? Seems easier to me. But then I'm a woman.......

 

And another thing - when the factory figures are obtained on a bench, the engine is all spangly and new.(no gritty bits) If I were to do the same on my engine by removing all plugs (even after blowing compressed air around the bases of the plugs) I'm not sure I'd trust one of those cylinders not to ingest a little flake of grit or something from around an open plug hole.

 

One plug at a time (for me) on an engine that's been in the real world.

 

Sorry if I'm stepping on any toes, but I'm just learning here too!

 

Just asked Soop Dogg and he reckons he'd do it this way to be safe. Very little difference in the final reading between the two methods unless the gauge is particularly accurate which apparently many aren't!

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Can't you just leave the fuel pump plugged in and just remove the efi fuses as someone else said on here? Seems easier to me. But then I'm a woman.......

 

And another thing - when the factory figures are obtained on a bench, the engine is all spangly and new.(no gritty bits) If I were to do the same on my engine by removing all plugs (even after blowing compressed air around the bases of the plugs) I'm not sure I'd trust one of those cylinders not to ingest a little flake of grit or something from around an open plug hole.

 

One plug at a time (for me) on an engine that's been in the real world.

 

Sorry if I'm stepping on any toes, but I'm just learning here too!

 

Just asked Soop Dogg and he reckons he'd do it this way to be safe. Very little difference in the final reading between the two methods unless the gauge is particularly accurate which apparently many aren't!

 

 

Not at all ..I think most of us skin a dog in a different way. Like you say some people like to do it with plugs in some dont ..no beef ..it's just prefference.

Not jumping on anyones throat or anything like it . I just do what i do and what i was trained to do others dont ..Hey thats the world . I like to base my figures on what TSM/factory specs are and factor wear ..and some base them or like you say real worlds figure...some like bacon some dont . Its all good at the end of the day we all end up with results we can work from.:ok:

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