[Explorerlyon]

EDIT: SEE POST #24 FOR WHAT WAS THE CAUSE OF THE ISSUE.

Codes: 29D1, 29D2, 29D0 and 29CC. (06 330i, 200k miles, automatic).

Car ran perfectly. Parked it for 2 hours. Upon restart the engine knocks, vibrates and RRMs are very low to high.

1. I had just cleared all the codes. New code was only cylinder 5-29D1.
2. Changed all 6 sparkplugs (it was time, 200K). No change in code.
2. Swapped coil pack #5 with cylinder #1. No change in code.
3. Swapped Injector #5 with injector #1. No change in code.

Ran the car much longer this time to see if more codes would generate. That is when I got the codes listed above for all 3 cylinders.
Ground wire for cylinders 4, 5, 6 looks good and secure.

What do I troubleshoot next?
I have INPA and ISTA.

[relative4]

B2S1

[Explorerlyon]

Originally Posted by relative4

B2S1

I assume you mean the o2 sensor? Is there a way to test the o2 sensor or just replace it?

[Explorerlyon]

I replaced B2S1 o2 sensor. Did not fix or change anything. What do I troubleshoot next?

[lowrydr310]

Have you triple checked the connectors to the coils? First time I had coils off an E90 I didn't get the connectors seated properly. Pushing the plastic lever down wasn't enough, I had to push the connector in firmly at the same time.

There might be other things to check first, but it's not impossible that you have several coils intermittently failing arouns the same time. I had a misfire on my 325 and tried swapping coils and ended up getting more misfire codes from cylinders I didn't touch. After 6 new coils and plugs, it's been running fine ever since.

[smass]

If you have an ohmmeter, check the brown ground wire resistance between 1-3 to negative and 4-6 to negative and compare. Tripple check the ground wire bolt. The threads in the valve cover can be stripped easily and it might not be making a perfect connection. Also check the ground strap between the valve cover and body. Lots of people have issues with the grounds and the 06 magnesium valve cover.

[Explorerlyon]

Originally Posted by lowrydr310

Have you triple checked the connectors to the coils? First time I had coils off an E90 I didn't get the connectors seated properly. Pushing the plastic lever down wasn't enough, I had to push the connector in firmly at the same time.

Just removed all 6 connectors. Reinstalled by pushing each connector al the way until seated fully, then closed the retainer. No change in condition.

Originally Posted by smass

If you have an ohmmeter, check the brown ground wire resistance between 1-3 to negative and 4-6 to negative and compare. Tripple check the ground wire bolt. The threads in the valve cover can be stripped easily and it might not be making a perfect connection. Also check the ground strap between the valve cover and body. Lots of people have issues with the grounds and the 06 magnesium valve cover.

Removed all 6 connectors. All 6 have continuity to the negative post (where you would jump start). All 6 have between 0.4-.5 ohms between plug (brown wire) and grounding screw for the coils.

[Clammy]

Had a similar thing going on with my '06 330i, and thought it was a bad fuel injector. Took it to my regular shop with new injectors, and got a call a little while later. Before doing anything, they performed a compression test, and found that the engine had lost compression on cylinder 6. I'm in the process of getting a used engine for my car, now.

Not saying this is what's going on with your engine, but doing a compression test might be a good idea.

Hope it isn't the same problem I had. Good luck.

Cheers!

[TunafishE93]

Did you check the resistance of the other pins to ground, not just the brown wire? Make sure you dont have short to ground on other pins or pin to pin short.

[apascutia]

Curious to find out what's going on here. Hopefully, it's not too serious.

[Explorerlyon]

Originally Posted by Clammy

...Before doing anything, they performed a compression test, and found that the engine had lost compression on cylinder 6. I'm in the process of getting a used engine for my car, now.

Not saying this is what's going on with your engine, but doing a compression test might be a good idea. Hope it isn't the same problem I had. Good luck.

Unfortunately, you were right. Just did a compression test.
Cylinder #5: Zero compression
Cylinders 1, 2,3,4,6: 185

[Clammy]

Originally Posted by Explorerlyon

Unfortunately, you were right. Just did a compression test.
Cylinder #5: Zero compression
Cylinders 1, 2,3,4,6: 185

Damn... sorry to hear that.

Mine just did it out of the blue, too. I was at a red light, when all of a sudden it dropped a cylinder. I had been having a mildly rough running issue, and one of the injectors WAS not operating correctly, but other than a bit of a rough idle, it had been running pretty normally. The injector that was acting up was the #6, so I'm thinking it went super lean at one point and put a hole in the piston. I won't know for sure until the engine swap is done. Before sending the old engine to the scrap yard, I'll pull the head, and see what's going on.

[Explorerlyon]

Originally Posted by Clammy

Damn... sorry to hear that.

Mine just did it out of the blue, too. I was at a red light, when all of a sudden it dropped a cylinder. I had been having a mildly rough running issue, and one of the injectors WAS not operating correctly, but other than a bit of a rough idle, it had been running pretty normally. The injector that was acting up was the #6, so I'm thinking it went super lean at one point and put a hole in the piston. I won't know for sure until the engine swap is done. Before sending the old engine to the scrap yard, I'll pull the head, and see what's going on.

Where did you find your replacement engine?

[Clammy]

Originally Posted by Explorerlyon

Where did you find your replacement engine?

From a Kijiji ad near me.

The engine was delivered to the shop today. It's from a 530xi with 85,000 kms (~53,000 miles) on it. My original engine has 218,000 kms (~135,000 miles) on it. The original clutch, flywheel, serpentine belt and tensioner will be replaced. The oil pan has to be swapped, and the valve cover gasket needs to be replaced. I'm also having a set of AA headers installed, with their tune.

Cheers!

[smass]

Originally Posted by Explorerlyon

Unfortunately, you were right. Just did a compression test.
Cylinder #5: Zero compression
Cylinders 1, 2,3,4,6: 185

Borescope #5. Could be caused by pieces of broken disa valve stuck in the intake valve.

https://www.e90post.com/forums/showthread.php?t=1510929

[lowrydr310]

Originally Posted by Clammy

The injector that was acting up was the #6, so I'm thinking it went super lean at one point and put a hole in the piston. I won't know for sure until the engine swap is done. Before sending the old engine to the scrap yard, I'll pull the head, and see what's going on.

Not likely. Any super lean condition would have been detected and you'd have gotten a SES light for lean mixture. I had a cracked PCV hose allowing unmetered air into the intake and almost immediately got a SES light.


The reliability of the N52 is pretty well documented. Loss of compression in a cylinder isn't impossible, but it's definitely not a normal occurrence for an engine that was maintained somewhat reasonably and not heavily modified (supercharger, nitrous, etc.) Failed fuel injectors are also not common for these engines.

Do either of you have any idea what caused these issue?

Please keep us posted when you pull the head. I'm very interested.

[lowrydr310]

Originally Posted by smass

Borescope #5. Could be caused by pieces of broken disa valve stuck in the intake valve.

https://www.e90post.com/forums/showthread.php?t=1510929

ding ding ding! This would be my best guess right now.

Notice these two nearly identical circumstances are both on 330s and not the 325/328. 330 has the DISA flaps.

I inspected my large DISA flap since it was easiest to access without removing the alternator and it looks great. A quick check of the part number indicates it's not original and has been replaced at some point. However my small DISA looks like the original (not updated) part from late 2005.

[Explorerlyon]

Originally Posted by lowrydr310

...Loss of compression in a cylinder isn't impossible, but it's definitely not a normal occurrence for an engine that was maintained somewhat reasonably and not heavily modified (supercharger, nitrous, etc.)

I didn't even think of checking compression first for exactly what you stated. Mine has no modifications and everything ran perfectly for the past 2 years (when I acquired it). What is really puzzling to me is car ran perfectly, then parked for 2 hours. Upon restart is when my issue began. Absolutely zero compression has me puzzled as well. Shouldn't there be some compression regardless? I just ordered a borescope to see what is inside that cylinder.

[Clammy]

Originally Posted by lowrydr310

Not likely. Any super lean condition would have been detected and you'd have gotten a SES light for lean mixture. I had a cracked PCV hose allowing unmetered air into the intake and almost immediately got a SES light.


The reliability of the N52 is pretty well documented. Loss of compression in a cylinder isn't impossible, but it's definitely not a normal occurrence for an engine that was maintained somewhat reasonably and not heavily modified (supercharger, nitrous, etc.) Failed fuel injectors are also not common for these engines.

Do either of you have any idea what caused these issue?

Please keep us posted when you pull the head. I'm very interested.

The SES light was lit, actually. No mods to the engine that I know of. I bought the car in October 2019, with 207,000 kms on her. I put another 11K kms on her. She ran great until the recent problems.

The fuel injector was definitely going bad.

I will know more in the coming weeks, as the engine swap is completed. The AA headers have a 3 week shipping delay right now, so it won't be soon.

Cheers!

[Clammy]

Originally Posted by lowrydr310

ding ding ding! This would be my best guess right now.

Notice these two nearly identical circumstances are both on 330s and not the 325/328. 330 has the DISA flaps.

I inspected my large DISA flap since it was easiest to access without removing the alternator and it looks great. A quick check of the part number indicates it's not original and has been replaced at some point. However my small DISA looks like the original (not updated) part from late 2005.

When the rough running first started, I pulled the large DISA, and found the flap missing. Pulled the intake, and couldn't find the flap anywhere, which makes me believe that it was gone before I bought the car. I replaced the broken DISA with a working one (latest revision), and it helped, but the car was still running rough, and eventually got to the point where it felt like I had a miss, so I assumed coils/plugs, and had them replaced, it was at that time the injector problem was detected. The tech at the shop gave me a bottle of Amsoil fuel system cleaner, and it made a HUGE improvement, but never got the engine back to 100% smooth, so I decided to replace the injector. (and the external CCV just in case), but the cylinder dropped before the parts got to me.

Cheers!

[Explorerlyon]

Pictures of my cylinder #5:

What is this right below the hole threads? This is in the 9'oclock position viewing from the passenger side. It did not move when I hand-cranked the engine.



See this Video for more detail:

[smass]

Some of the borescopes have a mirror attachment that allows you to look upward at the valves. You could also remove the big disa to inspect and if the flap is gone, borescope in the intake to see the other side of the valves.