Cylinder 4 at 60psi on compression test :(

[silver4est]

Engine was warm, did not unplug coil packs. Removed #4 plug, screwed in gauge, started car and it came out to 60. Have not checked other cylinders yet, checking again tomorrow and taking a look at valves with a borescope?
Time with my mechanical friend was very limited and rushed, leaves me with questions. What’s next?

It feels like it drives fine aside from the misfire, shake when not moving.

 

[T4R2014]

Soak the cylinder in marvel mystery oil. May free up a sticking ring. If nothing happens then just drive it.

 

[pokeyman]

Pour a little oil into the cylinder and due to compression test again if the compression goes up that means the Rings are worn out if not you might have a bad valve or a blown head gasket

 

[LittleCaesar]

See if your mechanical amigo has a leak down tester to verify just how bad that cylinder is for lacking compression.

 

[Bad Luck]

Engine was warm, did not unplug coil packs. Removed #4 plug, screwed in gauge, started car and it came out to 60. Have not checked other cylinders yet, checking again tomorrow and taking a look at valves with a borescope?
Time with my mechanical friend was very limited and rushed, leaves me with questions. What’s next?

It feels like it drives fine aside from the misfire, shake when not moving.

When you say you started the car, you mean the engine was running during the compression test? If so, that is a running compression test and will be much lower than a static (engine not running) compression test.

 

[19963.4lsr5]

When you say you started the car, you mean the engine was running during the compression test? If so, that is a running compression test and will be much lower than a static (engine not running) compression test.

Yes he needs to remove all the spark plugs and wedge the throttle wide open for the test to be accurate.


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[silver4est]

Yes the engine was started and running.

Will redo it and test each cylinder

 

[gamefreakgc]

Others have said it but that's not how you test compression. Needs to be done one at a time with the engine off, just cranking only. I usually unplug the MAF so it won't start.

If you really are at 60, a leakdown test will tell you where the compression leak is at.

 

[plcfcng]

well I have 2 cents. Make sure the battery is fully charged I do compression test with the engine cold just because its easier.

Remove all the spark plugs keeping track of where the wire go and inspect the plugs they tell you alot.

I would unplug each of the coil packs or find another way to disable the ignition system and pull the fuel pump relay.

I will block open the throttle with something like a screw driver handle keeping the throttle open at least 25% and make sure it won't hurt the throttle plates or if you have a buddy working the key he can hold the throttle down. (I use a remote starter button so I can see the gauge.)

Now how many rotations some will keep pumping till it gets to the highest number. I usually go about 7 rotations what I look for is the major peak on the first cylinder I test and then go 2 more revolutions then do all the cylinder the same amount of revolutions.

Write down each results for each cylinder when your done take a oil can with motor oil in it and squirt 2 squirts in the first cylinder and retest. Do this for each cylinder.

So now you have a dry test number and a wet test number it will not tell you quite as much as a leak down test but for me its enough. If you have a low cylinder and it comes up after the second test then the problems rings if it changes only a little then it's valves. If it's just valves the job is easier, if it needs rings it depends on how bad the cylinders and pistons. ( Time money knowledge.) So do the test post the results i'm sure you will get responses. :banana:

 

[silver4est]

thank you, I will get on this and post back