If it was indeed a code for a noncontributory cylinder, I'd rerun the CBT again. This time allow the computer to run the test all 3 times (when a cylinder fails, you can elect to run the test twice more, where the puter uses differing criteria to determine how lame the cylinder is).
When something like that comes up, it only gives you a direction to go. Any number of things can cause a cylinder to not be as useful as it could be. The next step would be to see if the cylinder is not performing as strong as the others (dirty injector, etc) or not at all. If not at all, I check for spark, inspect the plug and use a noid light on the injector. Then if needed, compression test that cylinder. If the compression is good, pulling the injector and bench testing it can be a next step.
If it was indeed a code for a noncontributory cylinder, I'd rerun the CBT again. This time allow the computer to run the test all 3 times (when a cylinder fails, you can elect to run the test twice more, where the puter uses differing criteria to determine how lame the cylinder is).
When something like that comes up, it only gives you a direction to go. Any number of things can cause a cylinder to not be as useful as it could be. The next step would be to see if the cylinder is not performing as strong as the others (dirty injector, etc) or not at all. If not at all, I check for spark, inspect the plug and use a noid light on the injector. Then if needed, compression test that cylinder. If the compression is good, pulling the injector and bench testing it can be a next step.
My dad told me to run it again and the same #4 cylinder came up. i to pull a 12 hour shift in bout 30 mins central time so i will check it in the morning...also im hearing some tapping from that cylinder to.
Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder
balance test. Low compression on one of these cylinders rules out the
injectors as being the most likely cause of the problem. Look at cylinders
that fail the cylinder balance test but have good compression. These
cylinders either have a bad injector, bad spark plug or spark plug wire.
Move the wire and then the spark plug to another cylinder and run the
cylinder balance test again. If it follows the moved wire or spark plug,
you have found the problem. If the same cylinder fails the test again,
the injector is bad. If different cylinders fail the cylinder balance test,
you have ignition problems or wiring problems in the 10 pin black &
white electrical connectors located by the EGR.
How to do a compression test:
Only use a compression tester with a screw in adapter for the spark
plug hole. The other type leaks too much to get an accurate reading.
Your local auto parts store may have a compression tester to rent.
If you do mechanic work on your own car on a regular basis, it would
be a good tool to add to your collection.
With the engine warmed up, remove all spark plugs and prop the
throttle wide open, crank the engine until it the gage reading stops
increasing. On a cold engine, it will be hard to tell what's good &
what's not. Some of the recent posts have numbers ranging from
140-170 psi. If the compression is low, squirt some oil in the cylinder
and do it again – if it comes up, the rings are worn. There should be
no more than 10% difference between cylinders. Use a blow down
leak test (puts compressed air inside cylinders) on cylinders that
have more than 10% difference.
Do a compression test on all the cylinders.
Take special note of any cylinder that shows up as weak in the cylinder
balance test. Low compression on one of these cylinders rules out the
injectors as being the most likely cause of the problem. Look at cylinders
that fail the cylinder balance test but have good compression. These
cylinders either have a bad injector, bad spark plug or spark plug wire.
Move the wire and then the spark plug to another cylinder and run the
cylinder balance test again. If it follows the moved wire or spark plug,
you have found the problem. If the same cylinder fails the test again,
the injector is bad. If different cylinders fail the cylinder balance test,
you have ignition problems or wiring problems in the 10 pin black &
white electrical connectors located by the EGR.
How to do a compression test:
Only use a compression tester with a screw in adapter for the spark
plug hole. The other type leaks too much to get an accurate reading.
Your local auto parts store may have a compression tester to rent.
If you do mechanic work on your own car on a regular basis, it would
be a good tool to add to your collection.
With the engine warmed up, remove all spark plugs and prop the
throttle wide open, crank the engine until it the gage reading stops
increasing. On a cold engine, it will be hard to tell what's good &
what's not. Some of the recent posts have numbers ranging from
140-170 psi. If the compression is low, squirt some oil in the cylinder
and do it again – if it comes up, the rings are worn. There should be
no more than 10% difference between cylinders. Use a blow down
leak test (puts compressed air inside cylinders) on cylinders that
have more than 10% difference.
Thanks man, i will try that when i get up. Had to work a 12 hour shift last night. But anyways i hope its not worn rings. By the way u r full of great information. Once again thanks man.