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1994 Toyota Supra Turbo 6spd
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Discussion Starter #1
it's a pretty basic procedure that i've done countless times in my supra. but i just wanted to see how everyone else was doing it. if the search function was up, i'd use it :)

anyway, i usually just pull all the plugs and go at it without using any throttle while cranking. i usually let it crank for 6-8 revolution to take a reading.

are there any sensors, fuse or anything else you guys pull, need to reset in doing your compression tests?

i've never done anything to mine and it has been running fine through the years :) just checking in with everyone
 

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Banned
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2,133 Posts
i do it this way:

Engine Cold
Pull EFI fuse
pull 1 plug at a time and hook up compression tester then crank

then reinstall efi fuse
get car up to operating temp
pull EFI fuse
pull 1 plug at a time and hook up compression tester then crank

reinstall efi fuse
drive car around a bit
pull efi fuse
leakdown test

takes a while but you get readings that you can actually compare.. cuz some people do it cold, others do it warm, and other times people ask for leakdown numbers... so do it all at once!
 

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1994 Toyota Supra Turbo 6spd
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1,517 Posts
Discussion Starter #3
you pull all the plugs out before you start cranking and checking #'s right? :)

that's a good way of doing it, getting one cold reading and one warmer. as far as leak down i've always wanted to do one, shouldn't be hard witha c ompressor. but how much PSI do you shoot in each cylinder?

post up details if you don't mind on the leak down testing! thanks
 

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235 Posts
you pull all the plugs out before you start cranking and checking #'s right? :)

that's a good way of doing it, getting one cold reading and one warmer. as far as leak down i've always wanted to do one, shouldn't be hard witha c ompressor. but how much PSI do you shoot in each cylinder?

post up details if you don't mind on the leak down testing! thanks
Heren ya go..its not MKIV specific but the info is good.

http://supraforums.com/forum/showthread.php?t=426570
 

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Boost4fun
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1,848 Posts
Just screw out all plugs at a cold engine, pull EFI fuse (or at least unplug the resistors of the injectors) that no fuel is being injected, go WOT and crank it for around 4-5 seconds for each cylinder (until the needle of the measuring equipment will not raise anymore).
That´s the most accurate way IMO.
Gerd
 

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Old School
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4,067 Posts
A nice trick is to pull the starter relay (the purple one in the engine bay fusebox) and jumper the driver's & passenger side socket terminals together (I made a jumper with a momentary contact switch).

This will spin the starter without ignition or fuel. And you can stand next to the engine and watch the gauge w/o having to get in the car to turn the key.

.
 

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I haven't noticed any trend to indicate that there's any need to run the engine between testing of the cylinders -- no trend toward lower readings on the later cylinders if you just warm up the engine thoroughly and then pull all the plugs at once a and do the test. I would also do the clutch switch bypass so you don't have to hold pressure on the thrust bearing during cranking, and put a battery charger on it so that the battery doesn't get weak and spin the engine slower on the later cylinders. And holding the throttle WOT seems to make a tiny bit of difference in how quickly the pressure reaches peak readings on the gauge.
 
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