I own an Ap1 with 169000km on it (105kish miles) and I've been debating between going turbo, or selling the car and getting a lower mileage one and then going turbo.

I did a compression test, and these were the results:

Back to front

Cylinder 1: 260-260-260
Cylinder 2: 240-240-240
Cylinder 3: 240-245-245
Cylinder 4: 245-250-245

I've had a valve adjustment done within the last 5000kms

What's up with Cylinder 1? Should I be concerned, or just run something through the car to try and clean the cylinder of any excess carbon buildup?

Cylinder 1's plug had a little more carbon than the others...

Thanks guys

 

My manual says nominal compression should be 228 psi with a maximum variation between cylinders of 28 psi. Hope this helps.

 

I would be happy about it and go for a long drive

 

Do it again, start with cylinder 4. see if your numbers change. high compression usually means excessive oil in the rings, or fauly reading. Carbon COULD cause it, but that is highly unlikely.

 

did it 4 times, exactly 260 each time

 

If the car runs and sounds fine, it probably is. I wouldn't worry about it.

 

The fact that it's consistent is good, and while your variances aren't "perfect", they're within OEM specs. Cyl 1 reading high is weird, but things could be worse.

Drive the car a bit and do the test again. Maybe an exhaust valve of Cylinder #1 isn't opening all the way? It could also be oil, or carbon buildup. I'd bet it's carbon buildup.

 

What can I run through to try and clean it a bit?

Car runs perfectly btw guys.

 

There's probably a reason for it. Fix that reason, and eventually the carbon will get burned off. You could try a steam cleaning or sea foam, but I've always been wary of putting fluids other than gasoline in my engine. Sea Foam would be my choice between the two.