Low Compression, Need Guidance

[xantdelucax]

so bought an 03 A4 with a snapped timing belt, long story short i replaced the timing belt, spring tensioner, pulley tensioner, and water pump. I removed the head and had it resurfaced all new valves and valves seals put it. Put it all back together and had a miss and didn't run quite right. I then drained the fuel tank got fresh gas and replaced the number one injector. started it up and ran fine other then what sounded like the chain tensioner. got in the car drove it made it to second gear and heard a loud blowoff of air and the car shutoff soon after. got it back to the house and spun the motor, was still free spinning and the belt was still their. tried to start it and it started extremely rough idle for 2-3 seconds then dies. tried again and held the gas and runs somewhat normal at high rpms. but when i let go it stumbles and dies, loss of power from idle to roughly around 2k. fuel and spark is good and no cel's, ran a wet and dry compression test and got 1- 60, 2-90, 3-105, 4-110, and wet 1-60, 2-90, 3-120, 4-120. with so little improvement with the wet test i assumed valve problem. removed the head to find all the valves good.

sorry for the long explanation just covering everything so i can get some help at this point. can't decide wear to go next? rings? have the valves tested? or am i missing something?
Thanks in advance for any help and feel free to ask or have me look at something.

[diagnosticator]

You need to fluid test the valves for leakage with the head off. With the valves for each cylinder closed in the firing order, fill each intake and exhaust port in the head with thin fluid like paint mineral solvent. The valve should not leak any fluid except for a small amount of dampness on the cylinder side of the valve. If more fluid leaks through the valve, then the head must be disassembled and the valves checked for straightness and bending, and the valve seats lapped in as needed to seal the valves with the valves closed.

The low compression could also be a combination of leaking valves and wrong cam timing.

If none of the valves are leaking the only other causes of low compression are the wrong cam timing and bad piston rings, but the rings pass the wet compression test.

[casey.d.felton]

I had the same (ish) issue. I had 3 bent exhaust valves between #1 and #2 holes. I couldn't visually notice that they were bent until they were taken out. An audi speciality nearby diagnosed it by doing a wet leak down test. I replaced those valves and presto. It was like a new car.


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