How to check compression on cylinder - 1996 Land Rover Discovery

0 compression doesn't make any sense. it could be valves compression Rings or head gasket. I've never heard a cylinder getting 0 compression. I would do another compression test and double check it

If the misfire is on one a particular cylinder or perhaps 2, these issues need to be addressed and checked...
1. Power to the spark plug.
2. Coils and spark plug condition.
3. Fuel supply to the cylinder
4. Air supply to the cylinder
5. Correct fuel/ air mixture to the cylinder
6. Cylinder compression. Low compression or a cylinder compression level below spec will result in a misfire. If the compression tester shows low compression in a cylinder the causes of the poor compression reading then need to be addressed.

The fault codes generated by the computer and read by an appropriate scanner will tell you which cylinder or cylinders are misfiring.

Check these three things in the misfiring cylinder: spark, gas, and compression. One of them is wrong or missing. For spark check the spark plug and wire. Make sure you have spark on the plug wire, a strong blue spark. For gas, the fuel/air mixture may be wrong. Does the fuel injector pulse, putting gas into the cylinder? Possibly you may have a leaking injector or a clogged injector.

If gas and spark seem okay, you need to check compression in the cylinder. Low compression will cause a misfire. If compression is 20 or 25% lower than adjacent cylinders, that could be causing a misfire. For example, say numbers 1 and 3 cylinders had about 150 psi compression. 80% of 150 = 120, so if cylinder 2 is 120psi or less, that could be setting the misfire code. Low compression can be caused by valves not seating well, or bad piston rings, bad head gasket- something in the combustion area of the cylinder is losing compression.

Checking the compression amounts to using a pressure measuring device either held and sealed by rubber gasket against the cylinder spark plug orfice, or could be threaded the same as your specific plug is. It is a measure of the compression pressure within your cylinder when it is on the compression stroke....meaning all valves closed and the cylinder going up toward the cylinder head resulting in compression. Reasons for low compression are worn piston rings, burnt or mis-adjusted valves, or could be a cracked cylinder wall, blown head gasket or a hole in a piston. Gasoline engines run much lower compression than diesels. For your compression pressure norm, Google in your engine or buy a service manual and it will have the specs in pounds per Sq. in.or PSI. Good Luck

Timing may be off. Have you checked it? Back firing could be valve timing problem; could also be too much gas-check injector spray pattern-should see a cone shaped pattern of fine mist on the throttle plates when cranking engine-this is if you have throttle body injection.
For $20-$30, you can buy a compression gauge tester and check engine compression. On a warmed up engine, pull all spark plugs, disable ignition and fuel delivery (pull injector fuse or unplug injectors), hold throttle wide open, and check compression on each cylinder by cranking engine over about 7-10 revolutions-the same amount for each cylinder, about 4-5 seconds each. All cylinders should be nearly even and balanced. Lowest cylinder should be at least 75% of highest reading cylinder. For any low reading cylinder, put a squirt of oil (about a tablespoon) in that cylinder and retest compression: if compression rises, rings are worn. If compression does not improve, valves are the reason for low compression-valves may be burnt or not sealing good.
I would do the compression test-on an engine that old, before putting expensive parts into it, you should know if the engine's internal mechanical condition is good first.

when you do your compression test squirt some oil in the cylinder through the spark plug hole first then check compression if you have compression then its rings. If still no compress you might have worn off cam lobes.

Hi,
That means u have to replace the piston ring on that piston in the #1 cylinder or check the intake/exhaust valve, it might have problem in sealing the cylinder during compression! If you have done the compression test, those are the main problem of loose compression. The only way to check it is to remove the cylinder head.
Hope that might helps u out!

#1 cylinder not firing, check spark plug, spark plug wire, remove spark plug and use a compression tester, and check the compression of that cylinder. should have at least 65 pounds of compression per cylinder. If the compression is low, you may try shooting a little oil in to that cylinder, replace spark plug, and try running motor again. if the compression is low on said cylinder, could be due to bad piston rings. requiring a motor rebuild.

Find the cylinder that is missing,and check the compression on the cylinder.If the miss is not narrowed down to one,or two cylinders,then run a compression test on all the cylinders,if while testing one cylinder,and the gauge fluctuates up and down,then check the one next to it,it it also is doing this,then the head gasket is leaking compression into one another.

A compression test will tell you if your engine has good compression. An engine is essentially a self-powered air pump, so it needs good compression to run efficiently, cleanly and to start easily.

As a rule, most engines should have 140 to 160 lbs. Of cranking compression with no more than 10% difference between any of the cylinders.

Low compression in one cylinder usually indicates a bad exhaust valve. Low compression in two adjacent cylinders typically means you have a bad head gasket. Low compression in all cylinders would tell you the rings and cylinders are worn and the engine needs to be overhauled.

HOW TO CHECK COMPRESSION
Compression can be checked two ways: manually with a compression gauge, or electronically with an engine analyzer the measures cranking compression. With electronic testing, a computer analyzer estimates compression in each of the engine's cylinders by measuring slight variations in engine cranking speed.

The results correlate well with actual gauge readings, and can be completed in a matter of minutes without having to remove any spark plugs. What's more, the analyzer prints out the results of the compression test making it easy to see and compare the actual numbers.

To check compression manually with a gauge, all the spark plugs must be removed. The ignition coil must then disabled or the high tension lead grounded. If the engine has a distributorless ignition, the ignition coils must be disabled to prevent them from firing. The throttle must also be held open.

The engine is then cranked for a few seconds using a remote starter switch or a helper while a compression gauge is held in a spark plug hole.

The maximum compression reading is noted, then the process is repeated for each of the remaining cylinders.

The individual cylinder readings are then compared to see if the results are within specifications (always refer to a manual for the exact compression figures for your engine because they do vary from the ballpark figures quoted earlier).

IS IT THE RINGS OR THE VALVES?
If compression is low in one or more cylinders, you can isolate the problem to the valves or rings by squirting a little 30 weight motor oil into the cylinder through the spark plug hole and repeating the compression test. The oil temporarily seals the rings.

If the compression readings are higher the second time around, it means the rings and/or cylinder is worn. No change in the compression readings would tell you the cylinder has a bad valve.

Hope this help (remember comment and rated this).