Low but very conaistent compression

[GermanEngineering]

I just did a compression test and got 85 across all cylinders. Car runs great and pulls good except for the idle but im running megasquirt so ive been trying to work that out. Just seems very weird and I feel like im doing something wrong. Any ideas? Had my throttle wide open during testing. Put a few squirts of oil inside cylinder and didnt help so its something with the top end.

[TobyB]

Cam adjustment can do that if you're running no lash.
Cam grind can do that if you're running a lot of overlap.

Inaccurate tester can do that if you shop at Horror Freight!

Try a leakdown next- and listen to where the air comes out.
If it's not coming out the valves, i suspect your tester.

you do crank it until the pressure stops rising, right?

t

[GermanEngineering]

I used a rented tool from autozone. I tried two different ones and still the same numbers. I will get a leakdown tester from harbor freight today.

The valve lash should be good.
225k motor btw

[e30sh]

Two cheap gauges? Oil will normally bump it up a little with a small valve leak.

Read the Harbor Freight reviews. They are based on 10 psi vs the std 100 psi. They are good however for locating air leak locations.

[GermanEngineering]

So here is what i got..
2 different autozone rentals- both showed 80psi across all 6 cyl
1 new harbor freight gauge- 120psi all 6 cyl
1 new bosch gauge- 165 psi all 6 cyl

Harbor frieght leakdown showed 12% leakdown and i heard a little bit of leaking out the oil filler.

So between all the tests im pretty sure its fine.

[TobyB]

I'd run it.

t

[GermanEngineering]

Yuupp. Time to turbo this 225k mile motor.