Ok here is what I got for compression numbers, the reason why I did the test is because I got owned by my friends 06 sti stage 2, and I have the following mods in my sig. So here are the numbers.

cylinder 1) 152
2) 152
3) 130
4) 152

Now this is a real cheap gauges, so I believe that is why I am in the 150's, when my friend who is a tech used it gauge it was reading 1) 175, 2) 175, 3)152, 4)175... that was taken months ago.. before we did the head gasket and new arp head studs.. So after the new gasket and head studs, I am still loosing compression in number 3. Also if you add oil to the cylinder it does not go up in readings, and a leaking down test was performed before the head gasket was replaced to rule out a hurt motor, and it was only a 4% loss...


SO fellas can you help me out on what to do next?

 

bump

 

bumpity bump... come on fellas help a fellow evom member out..

 

did you do the compresion test on a warm or cold engine?

 

hot engine...

 

Could you duplicate the compression test with same result?

Do a leak down to see if rings or valves, might even be a head leak from the ARP install

Were you making 310 on a mustang at 22 psi?

 

We did the compression test 3 times same cylinder to make sure the test was accurate.

I have already did a leak down test, couldnt find a leak only 4% loss in air.

Yea I was making 310 on a mustang at 22 psi..

 

JAM told me to do it with the engine cold and the TB open to get the most accurate results. Your dyno numbers seem right in line

 

ah well i give it a college try in the morning lol to see if it changes.. but my car is very slow.. so i know there is a problem...

 

I never heard of this and since your rings checked good, I guess you could adapt a fitting to the #3 plug and apply a little air with the cylinder positioned on compression stroke. Loosen the manifold to see if it's the exhaust valve, figure a way to check for leaks at the intake valve, if neither then the head has to come off .

At least it's a good thing you caught it early

 

the head was already off the car about 1 month a go... valves looked fine and sealed... only conclusion I have came up with is the LIFTERS in cylinder 3 are no good.

 

Have lifters caused this on 4g63s before? If so then it's the next easiest thing to try - Good luck

 

do you have a ticking noise during cold starts that should tell if you have a bad lifter

 

I'm in the same boat...JAM "no-tick" lifters on the way!

 

If it is working leave it alone. Leak down test looks good with only 4% loss...