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Nautricity Nautricity is offline
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Default Consistent Cyl 3 Misfire - 10-12-2020, 05:56 PM

I’m relatively new to N54’s but am mechanically inclined. I only have a basic scanner at the moment and am unable to pull codes like an MHD could.
I have a 2008 BMW E92 335xi 6 Speed with 139K miles on it
Stock car no modifications at all

P0303 Cylinder 3 Misfire Detected
-HPFP replaced under recall
-Injectors replaced under recall (x4 Index 8's x2 Index 7's)
-Replaced All 6 Spark Plugs BOSCH ZGR6STE2
-Replaced All 6 Ignition Coils BOSCH
I want to assume Injector 3 is still good as I’d imagine it hasn’t failed that quickly (within 40K) and same applies to the HPFP
Car ran perfect otherwise, if I pull 1-2 it won’t misfire 75% of the time, but if I hold 3-4K too long it’ll misfire almost every time and turn on the CEL.

Any suggestions? Could really use the help.

Last edited by Nautricity; 10-13-2020 at 05:58 PM..
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Default 10-12-2020, 07:01 PM

I'd recommend getting some way to pull the BMW specific trouble codes to see if there is anything there.

At this stage you can't rule out the injector. 40K (i recently rebuilt an engine that had muiltiple bad injectors at similar miles) wouldn't be unheard of for an injector to fail. You need to rule this out or you'll be chasing around a long time.

If you show some pics of the spark plug from CYL 3 on here the gurus will be able to tell you if your injector spray pattern is 'off'....

If you replace the injector and the problem remains you'll need to consider mechanical issues in the cylinder.

If I were in your position, i'd do a compression (or better a leak down test) on that CYL just for additional data.
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Default 10-12-2020, 07:22 PM

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Originally Posted by CastleBravo
I'd recommend getting some way to pull the BMW specific trouble codes to see if there is anything there.

At this stage you can't rule out the injector. 40K (i recently rebuilt an engine that had muiltiple bad injectors at similar miles) wouldn't be unheard of for an injector to fail. You need to rule this out or you'll be chasing around a long time.

If you show some pics of the spark plug from CYL 3 on here the gurus will be able to tell you if your injector spray pattern is 'off'....

If you replace the injector and the problem remains you'll need to consider mechanical issues in the cylinder.

If I were in your position, i'd do a compression (or better a leak down test) on that CYL just for additional data.
Heres some pictures, the pictures are out of order so I labeled them, one of cylinder 1 which was good and 3 photos of cylinder 3
They all seem identical, and I believe might be original
I don't believe the car has ever been walnut blasted, but that shouldn't cause a misfire necessarily, just reduced power
Imgur: The magic of the Internet
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Default 10-12-2020, 07:42 PM

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Originally Posted by Nautricity
Heres some pictures, the pictures are out of order so I labeled them, one of cylinder 1 which was good and 3 photos of cylinder 3
They all seem identical, and I believe might be original
I don't believe the car has ever been walnut blasted, but that shouldn't cause a misfire necessarily, just reduced power
Imgur: The magic of the Internet
Original plugs? So these are photos of the original plugs , but you have since replaced the plugs? Gotcha.

Clearly not covered in fuel like a leaky injector would be doing...might look a tiny bit 'dry' to me though. Given it's the only other thing you haven't swapped I'd consider replacing the injector or even swapping them to see if the misfire moves (don't forget to change the calibrations in the DME).
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Default 10-12-2020, 07:56 PM

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Originally Posted by CastleBravo
Original plugs? So these are photos of the original plugs , but you have since replaced the plugs? Gotcha.

Clearly not covered in fuel like a leaky injector would be doing...might look a tiny bit 'dry' to me though. Given it's the only other thing you haven't swapped I'd consider replacing the injector or even swapping them to see if the misfire moves (don't forget to change the calibrations in the DME).
How would I go about the calibrations? Im used to working on old BMW's and haven't had to deal with computers yet
The plugs and coils I changed tonight, and it didn't cure the misfire, so the plugs have maybe 5 miles on them.
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Default 10-12-2020, 08:23 PM

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Originally Posted by Nautricity
How would I go about the calibrations? Im used to working on old BMW's and haven't had to deal with computers yet
The plugs and coils I changed tonight, and it didn't cure the misfire, so the plugs have maybe 5 miles on them.
Ah...you'll need an appropriate cable and either a capable scan tool or software loaded on laptops. I tend to only use the BMW dealer tools (INPA, ISTA-D) etc but getting hold of these and setting them up is far too involved really...

Each injector has a calibration number on it and the DME needs to know that calibration so it can deliver the right amount of fuel...I'm wondering if this might even be necessary for a small test. I'd be inclined to try it and if the misfire moves or goes away you at least know it's the injector. I have no experience of what might happen if you don't change the injector calibration...I think it would be bad for actual normal use but can't see it being an issue for a test.

Another thing is if you have the injectors out you need some way to keep the o-ring compressed or it won't go back in, also it's good practice to replace the decoupler ring (and getting the injectors out without a decent tool is tricky also.

There is a big thread here on it...
N54 Injector Swap Coding Diy!
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Default 10-12-2020, 08:51 PM

Quote:
Originally Posted by CastleBravo
Ah...you'll need an appropriate cable and either a capable scan tool or software loaded on laptops. I tend to only use the BMW dealer tools (INPA, ISTA-D) etc but getting hold of these and setting them up is far too involved really...

Each injector has a calibration number on it and the DME needs to know that calibration so it can deliver the right amount of fuel...I'm wondering if this might even be necessary for a small test. I'd be inclined to try it and if the misfire moves or goes away you at least know it's the injector. I have no experience of what might happen if you don't change the injector calibration...I think it would be bad for actual normal use but can't see it being an issue for a test.

Another thing is if you have the injectors out you need some way to keep the o-ring compressed or it won't go back in, also it's good practice to replace the decoupler ring (and getting the injectors out without a decent tool is tricky also.

There is a big thread here on it...
N54 Injector Swap Coding Diy!
Thank you! I appreciate it, I might end up investing into a tool to be able to take care of modern BMW's.
Im going to pull some injectors from the junkyard and hopefully see how they work without calibration, iv seen videos without calibration running fine but obviously it exists for a reason
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Default 10-12-2020, 09:05 PM

Quote:
Originally Posted by Nautricity
Thank you! I appreciate it, I might end up investing into a tool to be able to take care of modern BMW's.
Im going to pull some injectors from the junkyard and hopefully see how they work without calibration, iv seen videos without calibration running fine but obviously it exists for a reason

Agreed, I don't think for diagnostics issues it will be a big problem...although be aware that there are 'old' (index 1 - 10) and 'new' (Index 11 and 12) calibration injectors that can't be mixed between banks..If all you had in your vehicle were index 7 injectors, you could mix and match them any way you like. Just another thing to be aware of, but many vehicles that have not had replacement injectors have much lower index injectors than 11.

You are in a good place in the world if you can pull working N54 injectors from the junkyard, most yards I've seen strip anything worth money out of all the 'desirable' vehicles :D

As far as scanning/coding tools go, I've seen good things about the Bimmergeeks Protool for Android , it's about 140 bucks but it has capabilities that only dedicated scan tools costing 10x the price would have. Although if you have the time and effort the BMW INPA tool will do everything needed (but it's a learning curve and requires a laptop).
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Default 10-13-2020, 05:17 PM

Quote:
Originally Posted by CastleBravo
Agreed, I don't think for diagnostics issues it will be a big problem...although be aware that there are 'old' (index 1 - 10) and 'new' (Index 11 and 12) calibration injectors that can't be mixed between banks..If all you had in your vehicle were index 7 injectors, you could mix and match them any way you like. Just another thing to be aware of, but many vehicles that have not had replacement injectors have much lower index injectors than 11.

You are in a good place in the world if you can pull working N54 injectors from the junkyard, most yards I've seen strip anything worth money out of all the 'desirable' vehicles :D

As far as scanning/coding tools go, I've seen good things about the Bimmergeeks Protool for Android , it's about 140 bucks but it has capabilities that only dedicated scan tools costing 10x the price would have. Although if you have the time and effort the BMW INPA tool will do everything needed (but it's a learning curve and requires a laptop).
I ended up pulling a full set off an 08 335i for $60
The injectors on my car are 4 Index 8's and 2 Index 7's (Keep in mind, an old lady owned this car before me, and it was only ever done at a dealership)
Index 9-4-12-12-12-12 in the picture, these are what I got from the salvage yard
I take it I shouldn't use 4 because its a different style injector, and shouldn't use 12's because they're the "new" versions, so clean, reseal, and use Index 9?
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Default 10-13-2020, 05:59 PM

Quote:
Originally Posted by Nautricity
I ended up pulling a full set off an 08 335i for $60
The injectors on my car are 4 Index 8's and 2 Index 7's (Keep in mind, an old lady owned this car before me, and it was only ever done at a dealership)
Index 9-4-12-12-12-12 in the picture, these are what I got from the salvage yard
I take it I shouldn't use 4 because its a different style injector, and shouldn't use 12's because they're the "new" versions, so clean, reseal, and use Index 9?
Good find!

Yes as lucky as you are to have had a set of hopefully good index 12s they are not immediately helpful to you for diagnostics....unless we assume that the exact calibration / mix and match stuff doesn't really matter for the purposes of tracking down a misfire. You're sort forced to use the 9 here.

Also please do take care you let the pressure on the fuel rail reduce overnight before opening up any lines....these high pressure rails can do damage worse than blades.
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Default 10-13-2020, 06:25 PM

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Originally Posted by CastleBravo
Good find!

Yes as lucky as you are to have had a set of hopefully good index 12s they are not immediately helpful to you for diagnostics....unless we assume that the exact calibration / mix and match stuff doesn't really matter for the purposes of tracking down a misfire. You're sort forced to use the 9 here.

Also please do take care you let the pressure on the fuel rail reduce overnight before opening up any lines....these high pressure rails can do damage worse than blades.
Yep! I have been letting it sit, the price was cheap enough to justify buying just incase, if I do not need them I could always sell them.
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Default 10-13-2020, 06:34 PM

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Originally Posted by Nautricity
Yep! I have been letting it sit, the price was cheap enough to justify buying just incase, if I do not need them I could always sell them.
Assuming they are good and they probably are (as index 12s are pretty robust) hang on to them. You know with N54 you are going to need replacement injectors. I think the thinking out there is that index 12s "don't fail" but I don't think anybody has been running them long enough to really be sure.

Good luck with the troubleshooting and let me know if I can help. I'm not the best on diagnostics but I've rebuilt two N54s now so at least know my way around the hardware.
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Default 10-13-2020, 06:56 PM

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Originally Posted by CastleBravo
Assuming they are good and they probably are (as index 12s are pretty robust) hang on to them. You know with N54 you are going to need replacement injectors. I think the thinking out there is that index 12s "don't fail" but I don't think anybody has been running them long enough to really be sure.

Good luck with the troubleshooting and let me know if I can help. I'm not the best on diagnostics but I've rebuilt two N54s now so at least know my way around the hardware.
I really appreciate the help A LOT, especially since I haven't been able to find a solution anywhere else, and I'm relatively new to these cars

I did take a look at my cylinder 3 injector, and its oddly yellowed, all others are white, which to me, might tell me it overheats somehow and burns away the color, but that's just an assumption knowing how some colors "yellow"
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Default 10-14-2020, 12:26 AM

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Originally Posted by Nautricity
I really appreciate the help A LOT, especially since I haven't been able to find a solution anywhere else, and I'm relatively new to these cars

I did take a look at my cylinder 3 injector, and its oddly yellowed, all others are white, which to me, might tell me it overheats somehow and burns away the color, but that's just an assumption knowing how some colors "yellow"
Unless it's some mechanical issue with CYL 3, fuel via the injector is the only thing that you haven't ruled out. Given it's always on the same cylinder I'd be at a loss to think what else it could be if it's not the injector now .
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