[aaron_]

So the car will occasionally (once every week or two) go into reduced power mode. Turn off and back on, and it's like it never happened. Error code that keeps coming up is 36C9 fuel mass plausibility or something like that. Had other issues before this (will spare you from the essay), as a result the jb4 and oiled afe CAI have come out. Those issues (really rough idle leading to stalling) have stopped but this has started. Had software updated and still there. Any clues as to what's causing this reduced power mode? Only happens at wot very infrequently, and I drive about 600kms per week

Thanks!

[Fuji]

http://www.1addicts.com/forums/attac...2&d=1317300396
^ That's a good list of N55 error codes.

For the one you're referring to, it seems to be an issue with one of the following:
- Rail pressure sensor faulty
- Wiring harness defective
- DME defective

I'd start by checking out the rail pressure sensor.

All the best

[aaron_]

Thanks very much for that. Will have a look into part numbers on real oem tomorrow. If I struggle I'll ask in here

Appreciate it mate!

[Fuji]

No probs, let us know how you go!

[aaron_]

I got prices and part numbers from a BMW dealer as follows:

Rail pressure sensor 13537620964
Wiring harness 12417592511
DME 12148618483 (only if first two don't fix it)

Searched ECS, rail pressure and wiring harness part numbers yield no results, and DME has been superseded by a new part number

Where do I find the first two parts overseas if the au number doesn't bring anything up?

[Fuji]

Maybe you could try swapping over a known good rail pressure sensor with someone off the forum? I'm not sure how much these cost - if not much, might be worthwhile just purchasing one and testing it out. As for purchasing a new DME, I'm sure that would be an extremely expensive exercise and you'd want it to be diagnosed 100% as cussing your issue before replacing it.

[aaron_]

I want to just buy one, but I can't find it! The part number I was told doesn't bring anything up. Only after the sensor and harness are changed will I consider the DME (if problem persists)

Problem with swapping is the code isn't always there. Once they're reset it might take 2 weeks for it to reappear.

[vtl]

Originally Posted by aaron_

I got prices and part numbers from a BMW dealer as follows:

Rail pressure sensor 13537620964
Wiring harness 12417592511
DME 12148618483 (only if first two don't fix it)

Part number is 13537620946, looks like you got a typo

I doubt the sensor is the issue though, the rail pressure sensor isn't really a common failure.

[aaron_]

Thanks for that, what do you think it is? Harness, DME or neither?!

[Fuji]

Could this be the part you're after?
https://www.turnermotorsport.com/p-2...0-f01-f10-f12/

This is a link to a guy swapping it over on an N54 engine. Seems like the sensor is a PITA to access and requires taking the intake manifold off.

Good luck!

[Fuji]

^ Another way of doing it without removing the intake manifold.

[DR-JEKL]

fuel pump plausability error code can be HPFP or LPFP sensor.

A shaky idle does indicate a LP fuel issue to me though, apparently the LPFP itself can fail also...

How many kays has your car done?

[aaron_]

Fuji - I think vtl sorted the part number for the rail sensor out. I think I got the last 2 numbers reversed. Thanks for the vids, will come in handy at some point!

Dr-jekl, the shaky idle is entirely gone. It's as solid as a rock now. Is the hpfp and lpfp sensors different to rail sensor? If so do they have their own error code? If so what are the chances it is one of those and the rail sensor code came up in error?

Car is on 66kms now. Bought it in October with 52kms, I drive a lot!

Car has had plugs, coils, micro filter, oil filter, oil, brake fluid, diff fluid, new water pump and thermostat, oem coolant since I've had it.

[vtl]

Originally Posted by aaron_

Fuji - I think vtl sorted the part number for the rail sensor out. I think I got the last 2 numbers reversed. Thanks for the vids, will come in handy at some point!

Dr-jekl, the shaky idle is entirely gone. It's as solid as a rock now. Is the hpfp and lpfp sensors different to rail sensor? If so do they have their own error code? If so what are the chances it is one of those and the rail sensor code came up in error?

Car is on 66kms now. Bought it in October with 52kms, I drive a lot!

Car has had plugs, coils, micro filter, oil filter, oil, brake fluid, diff fluid, new water pump and thermostat, oem coolant since I've had it.

Have you fully removed the JB4? Sounds like a code you could get with a piggyback.

[aaron_]

Yea jb4 is off Completely now. Has been for a while. Was very unhappy with it. Only aftermarket parts are the ER chargepipe and vrsf 7" fmic. I even uninstalled my oiled afe CAI to eliminate as many variables as possible. When this is all sorted the CAI will go back on

On a side note, would the CAI or jb4 bring up a running lean error code?

[wynes]

Hey, did you sort this code out? If so, what resolved it?

[aaron_]

Ended up changing boost solenoid and vacuum lines - good as gold

[EB89]

Originally Posted by aaron_

Ended up changing boost solenoid and vacuum lines - good as gold

Nice, good to hear, man you have been through the wars :/

[Socket]

I love a happy ending

[aaron_]

Originally Posted by EB89

Nice, good to hear, man you have been through the wars :/

I think the car was neglected before I bought it. I've changed all fluids and filters, multiple gaskets and radiator hoses, had my cp blow, done the boost solenoid and vacuum lines, had a walnut blast and full dct service and changed out the plugs and coils along with 10000km oil changes and a new battery.

I'm sure there's other stuff too but it Runs perfectly now!!

[EB89]

Originally Posted by Socket

I love a happy ending

[wynes]

Originally Posted by aaron_

Ended up changing boost solenoid and vacuum lines - good as gold

That's great news!!
Was there a specific vacuum line that you replaced?

I would have thought if it was a boost solenoid it would have thrown another fault code?

Cheers!