So i recently had some issues starting my car , and i went ahead and did a compression test...
Test was done on a Cold motor w/ WOT (fuel pump fuse pulled)
-Cyl 1 - 119 psi
-Cyl 2 -121 psi
-Cyl 3 - 90 psi
-Cyl 4 - 118psi

Obviously theres something wrong here at Cyl #3... not sure how to approach this issue. ANY IDEAS?

 

needs to be done hot/WOT. and your motor is ok cause the numbers are all pretty close in relation.

 

90 psi compared to 120 psi is not a close relation... I will do another test with the motor warm.

 

120 is really low, that is like lower than my civics compression. how many miles on it

 

That is not okay, at all. It is supposed to be with the motor warm. Which will yield a slightly higher number, but they are still going to be low, and a big diff. from cyl. 3

 

And the numbers between cyl. Must be within 20psi

 

If you did the test correctly and the gauge was working your engine is completely done. I think it should be 240 per cylinder if I remember correctly. Also that difference in the 1 cylinder is waayyy too big of a difference. All should be within 15 psi at the most.

 

we need more info to make any sense out of this.

is your car at stock compression? are you n/a or fi? do you daily drive your car? have you noticed any decrease in performance/increase in oil/coolant consumption?

talk to us!

 

don't worry about the overall compression numbers. Each compression tester will be different. All you need to pay attention to is the percentage difference between the numbers. That is what is important when seeing if there is a problem. Now that you have found a low compression in a cylinder, you need to find out why its low. Pour a teaspoon of oil into that cylinder and redo the compression test. If the numbers jump up, you know its a ring issue. If it doesn't, its something to do with the head. good luck

 

Hey---warm the car before taking a compression.
As I said, metal contract/expand. Engineers calculated the tolerance.
It's not accurate if the engine is cold.
Must be in operating temp.
Take the 4 sparkplugs OUT first (don't mix the wires).
Insert the compression tester - crank the engine in WOT (wide open throttle) butterfly must be opened.
Let us know.