ok well I have had a rough idle issue. Did the basic tune up stuff, then found the cracked exhaust manifold, replaced with the Tacoma mini header. Problem still there. Then realized that maybe i had a burnt valve. Did compression test. #1-0, #2-30psi, #3-60psi, #4-70psi. OUCH. Off came the valve cover to check valve adjustment. #1 Exhause was less than .0015 and .0030. #2 was .0015 and .004 then bouncing from .003 to .007 on the rest of the exhaust. Intake was all within spec. Did valve adjustment. Car idles as smooth as ever and returned to power. ONE PROBLEM. #1 cylinder 30psi compression #2 45psi, #2 90psi, #4 90psi. I would think if there was still a problem I would have some sort of drivability issue. Oil and coolant looks fine. So I am confused.

Oh by the way its a 3rz 4 cylinder 2.7L.

 

Were you holding the throttle open during the compression test?

 

rings?

 

Was not holding throttle open and not sure about rings however I believe that rings that bad would create very poor performance but I could be wrong

 

You have to remove all plugs and hold the throttle open while cranking to get an accurate compression test.

 

Thanks I will give that a try and report back

 

No difference in compression

 

Try a "wet" compression test - squirt some oil down each spark plug hole and test again. This seals the rings to rule them out. If it improves, you have ring issues. If it doesn't improve, your problem is the top end, like the valve sealing (which you fixed) or a head gasket or something.

 

Well tried the wet compression test. had a jump of 40psi. Looks like rings are wore out. Vehicle has 146k. Very disappointed as I have always been a toyota fan and expected many more miles. I have had this runner since new 1999. taken very good care of it but did pull alot of mountain passes with the family suffed inside. Never towed a thing with it. I am just disappointed. So when I decided to jump into a new engine what is the best way to go? How hard and expensive is a 3.4l swap? I have a 5speed manual transmission by the way too.

Great forum by the way.

 

I'd pull the head and take some pictures. You're just taking wild guesses at this point.