Compression test - what range values?

ZoomZ · 05-21-2020, 11:32 AM

Quote:

Originally Posted by RanRich

Bumping this thread to inquire about compression on higher mileage engines.

I have a 2009 with 112K miles on it, that's been tuned for about 50K. Just got a compression test and all cylinders were at 150, give or take a couple psi. I don't know if this was done hot or cold, and was just done at my local shop vs. a dealership. A bit worried about those numbers given what I've just read even though they're consistent and the car seemingly runs and drives just fine.

The shop (which has a lot of experience building their own and working on tuned cars) didn't sound at all concerned over the phone either. Is this engine on its way out or am I worrying about nothing?

Try different gauge, and hot. Also note the FSM calls for 200 RPM for those numbers. Make sure you are on a power supply not just battery. I'm guessing 150 was taken cold. FSM calls for warmed "thoroughly" engine, Fuel depressurized/fuse out, all plugs out, ACCELERATOR PEDAL FULLY DEPRESSED, and fully charged battery (I'd use a power supply).

If you get low readings still, pour some engine oil into cylinder from plug hole. take readings again, If pressure increases, you have worn rings.

zz

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