Post Headgasket/Bigsert compression # and codes

[Effduration]

I am not as certain as upallnight is that the compression figure variation is the source of your misfires...

I have seen similar compression figures on several M54's, both in terms of absolute value and variation, and they have not been mis-firing.

OP's mentions an old and possibly tired compression tester and finger tight sealing of the tester. My guess is if he ran the test again he might get different #'s

pull fuel pump fuse
pull ALL coils and spark plugs
fresh battery, maybe plugged in to a charger
Engine warm

[ahlem]

More update.
I unplugged the MAF and no more random misfires. Still have the solenoid valve code and now a MAF code. Will swap the valve and clean the MAF and report back. Idling smoothly in the driveway. Got 2 DISA and 3 solenoid valves at LKQ today for $28. One valve works and 2 DISAs work.

[ahlem]

Plugged the MAF back in and as soon as I hit the accelerator under load the misfires returned. I'm wondering if I screwed up the Vanos reinstall somehow. I will probably swap one of the coils and spark plugs to see if that makes one of the misfire cylinders better.
Can you drive around the block with the MAF unplugged. I know you can't with an M20 AFM unplugged.

[EODguy]

Yes you can drive with the MAF unplugged, it uses a stored set of values when disconnected.

One way to check your MAF is disconnect it from the filter side and leave it connected to the intake side plus the wire loom and tap it with the handle of a screwdriver while the engine is running. If it stumbles (engine) then it is toast and MAF *cleaner won't fix it.

*only use MAF cleaner not starter fluid or carburetor cleaner.

Sent from my SM-A730F using Tapatalk

[ahlem]

I drove around th block with the MAF unplugged and the ride was far superior to the plugged in ride yesterday. Should I assume the MAF is toast? I assume you whack it on the plastic perimeter rather than the wire mesh parts.
I still have the 44 Code for the solenoid valve.

[EODguy]

Originally Posted by ahlem

I drove around th block with the MAF unplugged and the ride was far superior to the plugged in ride yesterday. Should I assume the MAF is toast? I assume you whack it on the plastic perimeter rather than the wire mesh parts.
I still have the 44 Code for the solenoid valve.

I always tap right inline with film sensor to make sure it jiggles the hell out of the hot film. I would point out that I tap it more like a pissed of Nun with a ruler than something tentative.

But at this point for you I would also clean the harness connector to the MAF just to make sure it is the MAF not a dirty connector.

Do not buy the Land Rover compatible MAF or any aftermarket one as they're a crapshoot or 6-12 month item when put on or SAV's (don't ask how I know)

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[Effduration]

Originally Posted by ahlem

I drove around th block with the MAF unplugged and the ride was far superior to the plugged in ride yesterday. Should I assume the MAF is toast?

No. Most of the time, smoother running when you unplug the MAF, means you have a vacuum leak somewhere.

Get a smoke test done.

If you DO buy a MAF sensor, only after you pass a smoke test..You need to get an OEM or Siemens MAF..Don't buy a cheap one.

[andrewwynn]

+1 OEM

[ahlem]

I built a smoke tester a while back but would prefer to finish up another one that has a better designed smoke generator. That should be done in the next day or two and I'll try it out on this problem. I do have an extra MAF sensor but want to figure out the solenoid valve code without introducing a new variable. I'm thinking the potential vacuum leak and the solenoid valve may somehow be connected. Hopefully this will all be resolved shortly. Thanks for all the input.

[ahlem]

I ran the smoke tester at 5 PSI and discovered a good sized leak at the ICV elbow I was wrestling with a couple weeks ago when it was 15 degrees outside. I didn't get the elbow properly oriented in the notch it's supposed to align with.
I reinstalled the ICV properly on a sunny 45 degree day and ran the smoke test again. This time I found a smaller leak at the base of the DISA valve. I cleaned off the factory molded gasket and replace it with a new O ring and re-tested everything. It now holds 5 PSI that can be released by removing the oil filler cap. My few dollars at Home Depot and Harbor Freight to build the smoke tester were a good investment.
I put in a new set of cheapie stock NGK plugs from NAPA that I had.
I checked the fuel pressure at 52+/- PSI at the fuel rail.
I still have engine misfire codes on 1,2 and 3.
The injectors are original with ~170K miles.
I switched off injectors using my Foxwell scanner and got varying response.
I have a home built fuel injector tester/cleaner that will get used to see what's going on with the injectors.
Any other thoughts?
I still have the solenoid valve code and am wondering if the valve is stuck open causing a lean situation since it's near 1-3. I may try to take that off and retest it. It passed a bench and kiss test before I put it in.