I have done searches and not seen any real hard data as to the differences in psi observed doing this test COLD vs WARM. I have my engine bay apart tonight and as you could imagine I don't really want to put it all back together to obtain WARM temp to do the test and of course nor do I like working on a hot engine bay for obvious reasons.
So please answer to what you have SEEN cold compression tests show vs warm ones on the SAME ENGINE. This isn't a thread to bicker as I've seen some of the other compression threads do. This is a thread to try and find possibly an established PSI range difference that cold testing would show vs hot testing AS WELL AS TO CLEAR UP HOW COMPRESSION TESTING IS DONE ON OUR CARS for those that need to know.
Kicking questions/comments off right here is the official procedure from the manual (with a few added remarks) and yes I realize it says to test warm so I don't need to hear it. I know everyone isn't testing warm.
Procedure:
Page 11-14 ENGINE - On-vehicle Service
COMPRESSION PRESSURE CHECK
(1) Prior to inspection, check to ensure that the engine oil, starter motor and battery
(good charge on it) are in proper condition. Place the vehicle in the following conditions:
- Engine coolant temperature: 80-95°C (176-203°F)
- Lights, electric cooling fan and accessories: OFF
- Transaxle: Neutral (P for A/T)
(2) Remove the spark plug cables.
(3) Remove
all of the spark plugs.
(4) Disconnect the crankshaft position sensor connector.
NOTE: By so doing the engine control module stops performing ignition and fuel injection.
(5) Cover the spark plug mounting
holes with a shop towel, crank the engine, and then check for foreign substances deposited on the shop towel.
Caution
1. When you crank the engine, keep away from the spark plug mounting holes.
2. If a compression measurement is performed with water, oil, fuel, etc. in the cylinder due to the cracks in the cylinders, these substances heated to a very high temperature will blow off the spark plug mounting holes and could be dangerous.
(6) Install a compression gauge in a spark plug mounting hole.
(7) Set the throttle valve in a fully opened position
(unless the plenum is off already), and crank the engine to measure the compression pressure.
Standard value:
Non-Turbo 1,270 kPa (185 psi) [250-400 rpm]
Turbo 1,080 kPa (156 psi) [250-400 rpm]
Limit:
Non-Turbo min. 959 kPa (139 psi) [250-400 rpm]
Turbo min. 792 kPa (115 psi) [250-400 rpm]
(8) Measure the compression pressure in each of the cylinders and check that the difference in compression pressure between the individual cylinders is less than the limit value.
Limit: max. 98 kPa (14 psi)