Misfire cyl 4 & mixture too rich bank 1- long list of parts

A

al535e34

Member
Hi everyone, I’m new to the forum but long time BMW owner and wrencher.

I’m stumped with a 2006 3.0si n52 Z4 with 85k with misfire Cyl 4 & mixture to rich Bank 1 for now. Had Bank 1&2 but Bank 2 resolved after replacing a broken intake rocker eccentric arm.

Been through many troubleshooting but the misfire on 4 hasn’t changed. List includes the following:
1. Swapped coils around
2. Replaced plugs (2x) - platinum then back to iridium
3. Smoke test - found upper CCV hose cracked
4. CCV replacement (hoses and unit)
5. Injectors replaced with remanufactured ones
6. Upstream O2 Front/back replaced
7. MAF replaced with Continental MAF (replaced with a cheap one originally)
8. Checked/cleaned Vanos solenoids
9. Checked & Cleaned idle valves (2 small filter like on side of engine front - they were clean)
10. valvetronic unit tested including wiring from computer side
11. DISA valves replaced x2
12. Found broken rocker ecentric arm on Cyl 4 & replaced it
13. Replaced valve cover gasket, torqued to spec with new screws
14. Replaced oil filter housing oil & coolant gaskets
15. Compression tested which Cyl 4 was higher by about 10% (before replacing eccentric arm)
16. Reset adaptation & cleared codes what seems like 100 times
16. No blue smoke on startup
17. MAF connector was replaced early on
18. Tested wiring from ECU to coils, valvetronic and
Injectors, no issue
19. Tested voltage to ground for injectors and all seemed ok

IMG_2568.jpeg

I have INPA and cylinder 4 when running hard, is ok, else it can go to the 4-7 range. No lack of power and the original sputtering at start went away after replacing the eccentric arm.

I’m tired of throwing parts at it but I’m in the middle of trying to clean the post cat O2s and was thinking to replace them.

Obviously I have put a ton of money and time into it and just want it to run right and pass emissions as tags have expired. Any help would be greatly appreciated as I’m beyond frustrated with all the work done and no to little change especially the misfire on Cyl 4

Thanks,
Al
 
I think I'd be wanting to know how the rocker eccentric arm broke, I've never heard of that happening before. I know you have done a compression test, I think I'd try a leakdown test as well.
 
A long shot, how old is your battery. When mine started going it caused all manner of warning lights etc.
 
Rockhopper said:
I think I'd be wanting to know how the rocker eccentric arm broke, I've never heard of that happening before. I know you have done a compression test, I think I'd try a leakdown test as well.
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That was my boneheaded mistake. I replaced the valvetronic motor and didn't reset its limits. I think it was a bad motor and was locked and I heard the banging and thought that I bent some valves.

Mike6 said:
A long shot, how old is your battery. When mine started going it caused all manner of warning lights etc.
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Roughly 3 years old
 
I wonder if that's exactly what you have done? I've seen cars with okay compression readings fail a leakdown test because of slightly bent valves.
 
So I finally got a leak down tester and time to perform the test and nothing jumps out. I performed the test on Cyl 4 first and then decided to do all cylinders. Nothing really much. Cold engine gave less than 10% leak down in all cylinders. Only air hissing noise from the oil cap opening. Now what? :headbang:
 
al535e34 said:
So I finally got a leak down tester and time to perform the test and nothing jumps out. I performed the test on Cyl 4 first and then decided to do all cylinders. Nothing really much. Cold engine gave less than 10% leak down in all cylinders. Only air hissing noise from the oil cap opening. Now what? :headbang:
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Check the ccv, when past their best they feed oil vapour into the inlet manifold.
Rob
 
When you say misfire, how bad is it? Does the engine hesitate for a second and then clear or is it all the time? I would be looking at the wiring to cylinder number 4 coil pack.
 
al535e34 said:
So I finally got a leak down tester and time to perform the test and nothing jumps out. I performed the test on Cyl 4 first and then decided to do all cylinders. Nothing really much. Cold engine gave less than 10% leak down in all cylinders. Only air hissing noise from the oil cap opening. Now what? :headbang:
Click to expand...

See item 4 on my origins list. Unit and hoses have been replaced.
 
raymond.harper said:
When you say misfire, how bad is it? Does the engine hesitate for a second and then clear or is it all the time? I would be looking at the wiring to cylinder number 4 coil pack.
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The car runs great other than the check engine light and codes. Lots of power under load. Just can’t get it to pass emissions due to codes no have done continuity testing on the wires from the ECU to the coils. Fiddled with it while the car is running and no change. Swapped coils around, spark plugs including a new set.

After driving it for a bit and parking and letting it run, it feels like something is a miss and you can hear like something isn’t 100% right, drive away and you don’t notice anything wrong
 
This is all I could find on the E46 fanatics page https://www.e46fanatics.com/threads/too-lean-too-rich-combination-totally-lost.1003610/
 
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