Post Headgasket/Bigsert compression # and codes
 

Good Morning,
My post headgasket, head machining, Bigsert and valve job compression numbers on a 160K mile M54...
#1 172#
#2 154#
#3 158#
#4 158#
#5 158#
#6 170#

The compression tester is pretty old and the finger tight nature of this test is never my favorite.
I did not put any oil into the cylinders during the test to check the rings (yet)
Should these compression numbers be adequate to have a functioning vehicle until and if I decide to do the bottom end at a later date? I'd prefer they were a bit more even.
I have not had the fuel injectors tested. The coil packs are new with 0 miles.
I have to sort out the O2 sensor wiring.
I'm getting random engine misfire codes on #5 and one or two others but the others are not consistent.
After hearing thoughts on the compression I'll post the codes I'm getting.

Here are the codes...
Add a misfire for cylinder #3 as well.

Until the car is driven a bit with codes cleared I wouldn't be concerned about misfires. That said, after chasing misfires on wife's car it was injector cleaner that did the trick


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Any thoughts on the other codes? It seems the ECU is turning off some coils and if I clear codes it runs smoothly in the driveway until the misfire codes pop back up. I haven’t crawled around and looked from underneath to see if I forgot to connect a hose or wire when it was super cold.

When DME detects enough misfires it shuts off that cylinder. I was chasing one after another until I ran injector cleaner.

Small update...
The cylinder misfires do not occur if I hold the idle speed at 800 rpm or higher.
I sat there holding the pedal down a fuzz for 5 minutes and no misfire codes. If I took my foot off the gas pedal, the idle would settle to 550-600 and the misfire codes would pop up.
I'm thinking I should work on getting the other two codes to go away first and see if the misfire codes follow. Seems to me the situation is typical of a vacuum leak. My gut tells me the vacuum hoses running to the solenoid valve under the back of the intake are a potential culprit. I have the aluminum stiffener belly pan off so I might put that back on and take a cruise around the block to give the injector cleaner a chance to do it's work.
The Foxwell scanner I have doesn't give the same code numbers listed in my Bentley manual. Is there somewhere else I can access the same code numbers or do I need a different scanner?

You can drive without the stiffening plate if the back four bolts are replaced that hold the anti sway bar. Wife's has been off a while; makes the chassis more jiggly for sure. Feels like my old z28 when I had the top down vs up.

I suspect dirty injectors causing the misfire at low rpm. Put in a bottle of Lucas or tecron and drive half an hour or more to work it though.

Wife's mystery misfires stopped within an hour of driving never came back after two years or so. I put a bottle through every 9 months or so.

Update.. Made the 3E code go away by plugging in the electrical connector on the solenoid valve under the back of the intake. I'll check the other solenoid valve just in front of the Idle Air Control valve and take a good look at the DISA valve for the random misfire codes.
I think I have an extra DISA but they tend to need a little love at the big O ring if they pass the finger on the vacuum port test. I'll drive it up on ramps and take a dive underneath to see if I forgot anything else now that it's not single digits anymore. And put on the under tray and take a drive.

compression numbers are fine...

The low compression in cylinder 2,3,4, and 5 is the reason for the misfire code. A low compression in a cylinder will not make as much power as a cylinder with a high compression. Misfire in today's modern engine means the computer can detect the amount of power each cylinder is producing when the engine fire. The crank rotational speed can be computed by the computer and that is what determines a misfire.

Low compression can be leaky valves and worn bottom end. You can have a leak-down test performed to determine the source of the low compression.