I’ve got a 2.5l Subaru that is very shaky at idle. Did a vacuum test and the gauge needle shook rapidly between 10-14 inhg when idling. Just replaced all 16 valves and head gaskets and adjusted the valve gap so I don’t think those are the problems. What are your ideas?
2002 Outback 146k miles automatic.
All valve springs were replaced as well. It does throw p0302 and p0304 intermittently
Have you checked compression?
Just had a compression test done. cylinders 2 and 4 are giving about 110psi and 1 and 3 are at 175
Yea I think they are suppose to be within 10 percent of each other and I dont think that is 10 percent. Did you do it yourself or take it to someone? Sorry if I am incorrect I know on a boat motor its 10 percent.
General rule of thumb is cylinders should be within 10 percent. This is not even close. I can see where that large difference in compression would make for a shaky idle.
What do you think could be causing it? I don’t think it’s a leaking valve. Could it be that t the he head gasket isn’t sitting right?
You could do a wet/dry compression test to see if it's a problem with the rings seating (you've already done the dry part), and a leakdown test.
Did you replace the springs?
shaking would indicate misfiring. See our FAQ for more information on that.
Yes I had all the springs replaced