NebulaStilo
Member
- Joined
- Jul 18, 2019
- Messages
- 220
- Points
- 50
Your 1.6 has a compression ratio of 10.5:1 so I’d expect it to make around 150PSI. Was the engine hot and did you have all the spark plugs out, or just the cylinder you were testing?
You also need to hold the throttle fully open when you crank it.
The main thing though is that the readings were more or less identical and within 10% of each other. It’s not indicating any serious issue with the piston rings or valve seats, anyway.
The wet test was only a marginal improvement.. which normally suggests that the rings are okay and the lost psi are down to the valve seats or guides.. but the reading is so close to the dry test that even a tiny rings issue would read higher on a wet test.
If your valve guide seals are leaking then that doesn’t show up on the compression test, since that just measures how gas tight the cylinder is when the valves are closed. Not a bad result though.
Ralf S.
Yes the car was warm. Not right up at operating temp but warm.just came back from a drive.
How does it look? Seems to be a sensor issue?
I read that carbon build up can make compression high.
Also we don't know maybe the additive sealed off now is showing us we have good compression?Should have test before though. But if it is so, then problem would go away if compression is the problem.
The lower than the rest cylinder was number 3 and number 3 once or twice kicked out a misfire detected code.
If it's not compression then I'm going to have a look at good quality o2 sensor.
She will have a low idle on start up in the morning and I noticed when she does that, my scan tool says, o2 sensor heater:incomplete. Not as a code. Just as info it gives you etc. Then she will after 30 seconds she will bump up her idle and smoothen off. When she does that, tool says,o2 sensor heater:complete.
Maybe o2 sensor is lazy? This is the old o2. The new one is reading steady-ish voltage downstream but ecu don't like it in upstream???