[slamster]

******* UPDATE ******

I fixed the issue. Injector 6 was not properly seated. This was causing compression issues in cylinder 6.

I discovered this by pulling injector 6 out and meeting no resistance when pulling it out. I swapped injector 5 with 6 then recoded.

After that I went for a test drive and it was excellent!


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Hi All,

I've been having an issue with my n54 135i for a couple years now that has progressively gotten worse. I'm at a point where the car is undriveable. Here are the symptoms:

Runs fine during idle but under some acceleration it misfires and starts to shake violently. At that point, if I let off the throttle, it stays in that condition (misfiring uncontrollably) until I restart. Under restart, it is just fine (until I apply throttle again).

Things I have replaced to fix:

• Spark Plugs (Bosch)
• Coils
• Injectors
• VANOS Solenoids (both)
• Valve Cover Gasket

I also just walnut blasted my intakes with no change in symptoms.

I get the following error codes:

• 2AAF
• 29CD (misfire cylinder 1)
• 29CE (misfire cylinder 2)
• 29CC (again, misfire)

I'm really starting to get to the end of the road here.

My next thoughts are:

• Low Pressure Sensor
• Low Pressure Fuel Pump
• High Pressure Fuel Pump

Anyone have ideas/help! Any would be appreciated!

EDIT: I have JB4 installed. It misfires regardless of tune

Thanks,
Slamster

[slamster]

Tonight I looked at my Low Pressure Fuel Pump Sensor.

I loaded up INPA and monitored the pressure at idle. I got 48094 hPa which is ~710 psi.

It looks like it is a little low? Does anyone have any thoughts?

[type-dRew]

Isn't this a clear indication of mosfet issues? Or is that just if it misfires constantly without change.

[slamster]

That's interesting. I'll pull my DME and test my MOSFETS. My understanding, I just need to test continuity for the right connector?

[IllSic_Design]

I believe you test continuity on two pins on the mosfets themselves, been a while since I did it

[BM3Rrrr]

Reading the BMW Diagnosis for 2AAF it states:

The fault code 2AAF (if stored alone, or without any other faults related to the low fuel pressure system) is caused by DME diagnostic sensitivity, and should not be considered an indication of low pressure system malfunction.

DO NOT REPLACE the low pressure components (e.g., EKP Module, pressure sensor, electric fuel pump or filter) in order to address 2AAF

[IllSic_Design]

Post a log during a pull(or attempted pull) so people can check some parameters out. I'd like to see what your LPFP sensor and rail pressure read. I had other codes though, and not misfire codes, when I had a failing HPFP so I doubt it's fuel related.

[slamster]

I ordered some MOSFETS. I'm going to try and bring the DME into work tomorrow to see if the MOSFETS have continuity.

If so, I'll have a tech at work do the replacement of the components.

[slamster]

Just pulled my DME. Looks like it is a MSD81. I was reading on the forums. Seemed like the MSD81 doesn't have this issue. Could someone confirm?

Should I go ahead with the swap anyways?

[IllSic_Design]

Haven't really heard of MOSFET issues with MSD81, only 80. You have it out, test with a multimeter and see.

[slamster]

Just tested all 6... All of them seem to check out just fine. No beeping except the middle tab.

Any ideas?

[IllSic_Design]

Only thing I can say is post some/any type of log/s that you can get. Doesn't really make sense.

[slamster]

I agree, it doesn't make any sense at all.

I ordered up a USB OTG cable so I can use MDH. Once I get that, I will try and log some data. Is there a way to get any data from INPA?

I don't know of any other way to get info besides that. I am seeing misfires on cylinders 1-2. I just replaced all spark plugs, coils, injectors... I suppose I could swap out coils and plugs.

When i turn the car on, I also have some oil burning - visible oil smokes up from the front right (right side of vehicle). Perhaps something is wrong with the head gasket? Leaking? If it were leaking, maybe that would drive misfires. Not really sure, just a hypothesis at this point.

[Ilma]

Originally Posted by slamster

I agree, it doesn't make any sense at all.

I ordered up a USB OTG cable so I can use MDH. Once I get that, I will try and log some data. Is there a way to get any data from INPA?

I don't know of any other way to get info besides that. I am seeing misfires on cylinders 1-2. I just replaced all spark plugs, coils, injectors... I suppose I could swap out coils and plugs.

When i turn the car on, I also have some oil burning - visible oil smokes up from the front right (right side of vehicle). Perhaps something is wrong with the head gasket? Leaking? If it were leaking, maybe that would drive misfires. Not really sure, just a hypothesis at this point.

That sounds like a leaking valve cover gasket and the oil usually contaminates spark plugs leading to misfires and fouled spark plugs

The oil can also find its way to your exhaust manifold and cause smoking.

[slamster]

I just replaced my valve cover gasket. I guess it could be the case that it is still leaking... but it was smoking before and it is still leaking. It could also be a cracked valve cover...

I will certainly take a closer look

[slamster]

I just started my car again tonight. Strangely enough, no smoke. (I guess that is a good thing... although I don't like not know when something was fixed). The only difference was changing the JB4 map back to map 1 and also removing/reinstalling the DME. Perhaps there was some residual oil on the exhaust. I did notice a very small oil stain underneath the car.

So I ran a couple more tests to be certain it wasn't the plugs or the coils. As I was getting misfires on cylinders 1 and 2, I decided to swap plugs 3 and 4 for 1 and 2, respectively. I reran my WOT test. Like clockwork, it started misfiring on cylinder 2 (I didn't REALLY punch it for a significant amount of time which likely led to only cylinder 2 misfiring).

I then swapped the 1 and 2 cylinder coils for 3 and 4. Again, misfires on 1 and 2.

Furthermore, I took a look at plugs and coils. Neither of them had much for oil contamination.

Once the engine misfires, it goes into misfire mode where the vehicle needs to shut off then turned on again. However, when in that mode, it is indeed misfiring. The INPA "Rough Running" tool shows the cylinder probes are outside of the operational band to confirm (although anyone could tell the engine is misfiring based on the whole vehicle shakes)

My USB OTG cable is coming but might be a week with the delivery slow down from Covid

So that is next on my radar. The thought did cross my mind of moving injectors around to see if the problem follows the injectors. I know that there is a conformable Viton seal for each injector so I am slightly concerned that that will get messed up if I swap injectors.

Has anyone swapped injectors like I describe above? damage, no damage?

[slamster]

Another part of the saga... I found a thread by Mr. 5 that he was able to do some reset adaptations to fix his misfire/stuttering issue. See the thread here:

Stuttering, Misfiring, Stumbling--Fixed!
https://www.e90post.com/forums/showthread.php?t=386376

This morning, I went and reset all adaptations via INPA-- no luck. I also went through and reset all individually as well. However, some of them were not available to reset. Still having misfires. So I guess that rules that out unfortunately...

I noticed that the language was not the same between bavauto resets and INPA resets. Are there more resets that I am not clearing when going through INPA?

[autoart]

Have you tried the throttle relearn procedure?

[slamster]

Are you talking about this?

1. Never touch the brake pedal & leave the key inserted the entire time
2. Insert key and push START Button
3. Press and HOLD accelerator pedal for 30 seconds.
4. WITHOUT RELEASING THE ACCELERATOR PEDAL, push the START Button (remember without touching the brake, so the car doesn't really start yet.)
5. Release accelerator pedal
6. Wait 30 seconds
7. Start car normally

Edit: I should note, that I have a uneasy throttle as well. Meaning, when I accelerate, my throttle pulsates like when a newbie is just learning to drive a manual. Also, when i am in low RPM, the throttle surges

[autoart]

yes that's the one.

[slamster]

Yup, already tried that. No luck...

To summarize what I've learned so far about misfires:

• Spark Plugs - Just replaced. Although I've heard that people should use the BMW bosch vs normal bosch. They say it causes misfires...
• Coils - Just replaced them
• Injectors - Just replaced them (index 12 or 13). Could try swapping 1 for 3 and 2 for 4.
• HPFP - I haven't done this but I don't have long crank
• LPFP - Not sure if this would cause misfires but I read this "Not as common but a weak LPFP can cause misfires. You can measure this by trying to get logs from your tune of the LPFP voltage/pressure. You can also check your fuel trims to see if they are exceeding 31-34%. (However, your tune may just need adjustment). We advise to contact your tuner of choice in regads to fuel trims and if your low pressure pump may be on the fritz."
• LPFP sensor - I believe this is okay via INPA but I will check once i get MHD
• MOSFETS - I have MSD81 which means this is not an issue. Furthermore, I checked continuity on my MOSFETS and they all passed
• O2 sensor - not getting any O2 error codes
• Adaptations - I have reset all adaptations in INPA and also done the throttle reset procedure
• Carbon Buildup - Just walnut blasted intakes
• Valve Cover Gasket - Just replaced
• Vanos Solenoids - Just replaced. Didn't do OEM but no codes

[slamster]

Okay guys, I just got some data. Here it is:

https://datazap.me/u/slamster/202005...og=0&data=3-20

Please let me know if I need different channels logged.

Furthermore, i found an interesting post on another forum where a guy was seeing misfires on bank 1 (like I am). See the post here: https://bmw.***********.com/threads/...uel-trim.3456/

Basically, his front Cats were completely gone and had plug up his secondary cats. I'm wondering if this is what is going on in my vehicle. I definitely did have leaky injectors. I found another corroborating content here:

https://www.youtube.com/watch?time_c...ature=emb_logo

My hypothesis is that most N54 engines see discintegration of the front catalytic converter due to leaky injectors. This material then plugs up the secondary or primary catalytic converters. The N54 then becomes much more sensitive to any other effects (plugs,coils,injectors,vanos,etc) and manifests misfires.

Just a hypothesis. Will try and pull apart exhaust unless someone here has a better idea.

THANKS!