I have a few questions regarding my 2002 Impreza 2.5RS. It's having some starting issues. Sometimes it will start immediately, some times it will hesitate on starting, and other times it will just crank without actually starting. Every time it does not start, it sounds like a rifle has been shot. Here's whats been done recently: I've changed wires, both cylinder head cover gaskets (including the 4 spark plug boot gaskets), the timing has been checked (no belt/pump needed), and I've changed the crankshaft sensor. Earlier the car started like normal, but when shut off and I tried to start it again, it misfired and didn't start.

 

Today, I went to the shop that the car is sitting in now, and we checked the compression for the pistons. Here's what we got:

Cylinder 1: 60 PSI

Cylinder 2: 135 PSI

Cylinder 3: 30 PSI

Cylinder 4: 120 PSI

 

My mechanic seems to think that it is the camshaft, and that makes sense, since it is just the 2 passenger cylinders. However, he is not sure, and I want this done as quickly as possible.

 

So my main questions are: Has anyone experienced this before? Are there any ideas that someone has? Is any other information needed?

 

Thank you for taking your time reading this and for any feedback.

Edited March 11, 201610 yr by Muffinland

you have an issue with the passanger cylinder head. I doubt it's the camshaft. It's gotta be leaking compression. 60 PSI is barely enough compression to make a cylinder fire enough to support itself..

you have an issue with the passanger cylinder head. I doubt it's the camshaft. It's gotta be leaking compression. 60 PSI is barely enough compression to make a cylinder fire enough to support itself..

You believe it's the actual cylinder head itself? 

If those numbers are right it has jumped timing. Backfire makes sense if it has bent valves.

 

Need to do a leak-down test.

Edited March 11, 201610 yr by Fairtax4me

If those numbers are right it has jumped timing. Backfire makes sense if it has bent valves.

 

Need to do a leak-down test.

This is originally what I thought was happening, but all of the timing marks were where they should be. All the teeth on the belt are also in fine condition. Is there another way that the valves could've been damaged?

How long have you owned this car?

How long have you owned this car?

I've had this car since July 2015. It's always been rich and it's always done subtle backfires, but never like it is now. The problem developed about a month ago.

Lots of things that could have happened.

Previous owner could have installed the belt wrong and bent the valves.

If it's been running rich for a long time it cluld have severaly worn piston rings.

 

Either way, leakdown test will tell.

If you want to confirm, pull the passenger side head and check the valves and cylinder walls.