EML 35i

[Rich-hill]

Hi All.

Recently picked up a 2009 35i from a private buyer.
Full service history and 87k miles.

I have an EML issue I can’t figure out...

If I go through the gears in sport / comfort / manual everything is okay changing gear within 5500rpm.

If I use the kick down or manual so gear changes happen at the redline the following happens:

1st gear pulls all the way
2nd gear gets to close to 6000 rpm and power drops, EML comes on, if I come to a stop and turn the car off and back on the light has cleared and car runs normal.
If I replicate it in the same way, and roll to a stop a little slower, finding somewhere safe, the light will clear itself without a restart.

When the EML is on, the car runs and isles lumpy.

If I apply hard throttle in 2nd gear it will pull all the way, change to 3rd and the same thing happens as it approves 6000 rpm again.

I obviously can’t check this in all gears, but it only appears to happen when changing up and under hard acceleration for a prolonged period.

I plugged the car into a friends OBD reader and no fault codes appeared to be logged. Also when the EML comes on, the Idrive still says ‘no faults’.

Could someone suggest what this could be?

[mr wilks]

Traits of N54 ownership
Without code you could be playing a expensive guessing game.
Cheapest "possible" fixes plugs / coils but ideally look through paperwork / history to show if Hpfp or injectors have been replaced.

[Rich-hill]

Traits of N54 ownership
Without code you could be playing a expensive guessing game.
Cheapest "possible" fixes plugs / coils but ideally look through paperwork / history to show if Hpfp or injectors have been replaced.

We have plugged a code reader in twice and nothing has been recorded, which as you say makes things tricky.

The paperwork I have doesn’t show any sign of HPFP or injectors having been replaced.

I’m no mechanic myself... however coil packs and plugs should only be a couple engine cover screws and clips right? Any suggestions on which or where to buy replacements from?

[ph001]

Shame no codes stored. I don't think it will be coils as you would notice that at other rpm's / throttle openings. Could be plugs though as they are under the biggest stress at full boost and high rpms. Does tend to be a very obvious misfire though, but maybe the ECU is interrupting that by putting it into limp home mode.

I'd be changing all 6 plugs (from opieoils.co.uk) and if that doesn't fix it I'd be saving up for a new high pressure fuel pump I'm afraid.

[djstan]

What about a perished rubber hose somewhere? Back a long time ago I had an Audi S3, and forum members at that time were complaining of collapsing pipes which was causing boost problems? Just a thought...

[Rich-hill]

Shame no codes stored. I don't think it will be coils as you would notice that at other rpm's / throttle openings. Could be plugs though as they are under the biggest stress at full boost and high rpms. Does tend to be a very obvious misfire though, but maybe the ECU is interrupting that by putting it into limp home mode.

I'd be changing all 6 plugs (from opieoils.co.uk) and if that doesn't fix it I'd be saving up for a new high pressure fuel pump I'm afraid.

Okay I will go with plugs first.

As it doesn’t happen in a specified gear, but only after 2 gears worth of hard acceleration... like ‘time under load/power/boost.

[R.E92]

My guess would be HPFP. Fuel demand is highest at high revs. Typically a healthy HPFP will supply fuel pressure to the rail above 2000psi. It doesn't tend to cause fuel supply issues until it drops below 1500. You will see these kinds of symptoms on a car with a rail pressure dropping below 800.

The only way to diagnose a failing HPFP is to log the fuel rail pressure (using MHD or TestO). The typical symptoms are misfires at high revs and warm starting issues but these symtoms can be caused by failing injectors too.

On a any N54 engined car I would expect to be running on new HPFP, injectors and coils above 60k miles. If any of these components are still original then it's pretty much a waiting game.

[ph001]

Yep, agree - although it does seem to depend somewhat on what revision injectors you have. 1353 8648937-12 is the latest index 12 injector and seem reliable. They were £102 ech from a main dealer as of Jan 2018, but typically these were only used for warranty work and BMW will want to retail part number 1353 8616079-12 which is exactly the same but with a £240 price tag.

I think more times than not though, faulty injectors are characterised by difficulty in cold starts and a rough idle for a few seconds. They leak fuel overnight which results in bore wash and poor compression on startup.

I would be surprised if plugs or coil packs fixed it but for what they cost compared to the HPFP I would feel uneasy about not eliminating them as a possibility. I'd gladly have a small wager on the HPFP though.

[Rich-hill]

My guess would be HPFP. Fuel demand is highest at high revs. Typically a healthy HPFP will supply fuel pressure to the rail above 2000psi. It doesn't tend to cause fuel supply issues until it drops below 1500. You will see these kinds of symptoms on a car with a rail pressure dropping below 800.

The only way to diagnose a failing HPFP is to log the fuel rail pressure (using MHD or TestO). The typical symptoms are misfires at high revs and warm starting issues but these symtoms can be caused by failing injectors too.

On a any N54 engined car I would expect to be running on new HPFP, injectors and coils above 60k miles. If any of these components are still original then it's pretty much a waiting game.

Having read plenty online before buying the car, I feared this may be the case.

Am I correct in thinking the extended HPFP warranty was only a US market? Therefor here in the UK we are left to foot the bill?

Also I have no service record of any of the above being replaced, is this the sort of thing that would be stored on a BMW central database or will it be a case of ringing every garage that has seen the car?

[mcbutler]

Have you considered turbo overboost as you exceed the 5500 rpm mark?
Of course it may just be a sensor that is faulty as opposed to a working component i.e. a turbo boost sensor!
If it runs to the max in first when you have your foot hard down but not in second it gets a bit confusing.
You have to ask yourself what is different in 2nd to 1st?

A difficult one..

[Rich-hill]

Have you considered turbo overboost as you exceed the 5500 rpm mark?
Of course it may just be a sensor that is faulty as opposed to a working component i.e. a turbo boost sensor!
If it runs to the max in first when you have your foot hard down but not in second it gets a bit confusing.
You have to ask yourself what is different in 2nd to 1st?

A difficult one..

It’s not gear related. It happens the second time a full rev range is required.

Eg

1st gear to the limiter, EML before you get to the limiter in 2nd

2nd gear to the limiter, EML before you get to the limiter in 3rd.

Almost like it’s ‘time under load’

[enuff_zed]

Have you considered turbo overboost as you exceed the 5500 rpm mark?
Of course it may just be a sensor that is faulty as opposed to a working component i.e. a turbo boost sensor!
If it runs to the max in first when you have your foot hard down but not in second it gets a bit confusing.
You have to ask yourself what is different in 2nd to 1st?

A difficult one..

It’s not gear related. It happens the second time a full rev range is required.

Eg

1st gear to the limiter, EML before you get to the limiter in 2nd

2nd gear to the limiter, EML before you get to the limiter in 3rd.

Almost like it’s ‘time under load’

So, if you ran it to the limiter in first for example, then eased off in the other gears for a minute or so, then tried it again to the limiter, would it give you the EML?
I'm thinking if it was the HPFP, you may be giving it time to 'catch up' again and the problem may not occur.
Hitting the high revs twice in quick succession may not be giving it time to recover.
This could maybe help narrow it down to the HPFP.

[Rich-hill]

Have you considered turbo overboost as you exceed the 5500 rpm mark?
Of course it may just be a sensor that is faulty as opposed to a working component i.e. a turbo boost sensor!
If it runs to the max in first when you have your foot hard down but not in second it gets a bit confusing.
You have to ask yourself what is different in 2nd to 1st?

A difficult one..

It’s not gear related. It happens the second time a full rev range is required.

Eg

1st gear to the limiter, EML before you get to the limiter in 2nd

2nd gear to the limiter, EML before you get to the limiter in 3rd.

Almost like it’s ‘time under load’

So, if you ran it to the limiter in first for example, then eased off in the other gears for a minute or so, then tried it again to the limiter, would it give you the EML?
I'm thinking if it was the HPFP, you may be giving it time to 'catch up' again and the problem may not occur.
Hitting the high revs twice in quick succession may not be giving it time to recover.
This could maybe help narrow it down to the HPFP.

That’s exactly right, as long as it’s not limiter to limiter it won’t come on.

If I accelerate quickly in 1st or 2nd and hold the gear to the limiter, then shift early in the proceeding gears the light won’t come on.

[enuff_zed]

Sound like another vote for the HPFP then ....

[Rich-hill]

I had a full service earlier in the week so plugs have been changed.

The issue is still there though.

Change gear at 5,500-6,000 every time and you would never know there’s an issue.

No other symptoms occurs such as cold or warm start issues or mid fires and upon restart the EML goes away.