[jayess82]

Alright, a couple months back my e92 started missing pretty badly, so I parked it. I had codes for cylinder 6 and 4 misfires, along with multiple misfires. I ended up changing coils and plugs. The misfire stayed but only in cylinder 6. Tried swapping cylinder 6 coil around but misfire stayed at 6. I ended up replacing plugs again, but no change. Next thing was changing #6 injector. No change.

I've now got 29D2 (cyl. 6) and 29E1 (Mixture control 2). Can't remember if the last one popped up before or after changing injector. Did a compression test today and from 1 to 6 I had 190-210-210-205-185-0. This was done with a cold engine. I also did the cheap glove/cigar smoke test but didn't see any leaks. Trying to figure out what next step I should take before tearing it down. Recommendations? Didn't run hot, didn't get low on oil. Had no issues until it started missing.

[gbalthrop]

Originally Posted by jayess82

... Did a compression test today and from 1 to 6 I had 190-210-210-205-185-0. This was done with a cold engine... Didn't run hot, didn't get low on oil. Had no issues until it started missing.

You appear to know what you're doing, but it would be rather unlikely that #6 cylinder has NO compression at all -- 0. Particularly if there was NO event with "ominous" sounds from engine.

Since that is on the REAR cylinder, #6, which is hard to access depending upon the TYPE of compression tester hose used, I have to wonder if the tester "Sealed", particularly if you did NOT use the threaded type with an O-Ring seal. I note that #5 was "Next-Lowest" at 185 PSIG.

My suggestion is to REDO the compression test on #6 (particularly if smoke test did NOT show leak) and then use $20 (Amazon) USB Endoscope to examine inside cylinder #6, checking Valves & piston for any sign of contact or failure. That Endoscope can be used with either Phone or Laptop. Please let us know what you find.
George

[bmwbob89]

Leak down test this your next step. You have to find out if it's A valve Or a piston. Difference between pulling the head pulling the engine.

[jayess82]

Originally Posted by gbalthrop

You appear to know what you're doing, but it would be rather unlikely that #6 cylinder has NO compression at all -- 0. Particularly if there was NO event with "ominous" sounds from engine.

Since that is on the REAR cylinder, #6, which is hard to access depending upon the TYPE of compression tester hose used, I have to wonder if the tester "Sealed", particularly if you did NOT use the threaded type with an O-Ring seal. I note that #5 was "Next-Lowest" at 185 PSIG.

My suggestion is to REDO the compression test on #6 (particularly if smoke test did NOT show leak) and then use $20 (Amazon) USB Endoscope to examine inside cylinder #6, checking Valves & piston for any sign of contact or failure. That Endoscope can be used with either Phone or Laptop. Please let us know what you find.
George

It was the thread type with oring. I did each multiple times. When cranking on 6, it didn't sound like the engine was turning over. Completely different sound than on 1-5. I have video of the difference in sound but can't get them to upload.

I do plan on getting an endoscope to do just that.

[NZE90]

My money is on a damaged valve from one of your DISAS failing. If you are certain you have no compression on that cylinder, i would suggest removing the intake manifold to inspect the valves.

[jayess82]

Originally Posted by NZE90

My money is on a damaged valve from one of your DISAS failing. If you are certain you have no compression on that cylinder, i would suggest removing the intake manifold to inspect the valves.

I may be wrong but don't believe my 328i has any DISA valves. That was one thing I ran across when I started having the problem. I searched a ton looking for what else it could be. I saw where those valves would come apart, but did not notice any on my intake.

[jayess82]

Attaching pictures of plugs when I pulled to do compression test. 1-5 fouled. 6 is a lot less fouled.

[NZE90]

Yes, if it's a stock 328i it won't have DISAs. You may have to use an inspection camera in the cylinder then as others have suggested.

[jayess82]

Originally Posted by NZE90

Yes, if it's a stock 328i it won't have DISAs. You may have to use an inspection camera in the cylinder then as others have suggested.

Looks like that's my next move. Should have one here tomorrow.

[mictang]

I had the same thing happen to my old N52B25, which is prone to ring issues.

Nothing weird happened before and suddenly started misfiring one day, zero pressure in cylinder 6.

Poured a little oil through the spark plug hole and there were some pressure (very low). This led me to conclude it was a ring issue and swapped the engine.

I probably could have saved the engine by rebuilding it with new pistons and rings (I am pretty sure the cylinder wall was fine), but I always wanted to swap a B30 so I didn't bother.