[fabsp]

Good Afternoon,

My friend has a weird problem with his 2007 E92 335i N54.

The car runs absolutely spot on however when he pushes it and takes the car to high revs for a bit of spirited driving the engine management light randomly comes on sometimes and it says the car has reduced power and to take it to the nearest garage. There are however no other symptoms, the car drive completely normally with full power with the light on. If he switches the car off and on again the light disappears. This happens maybe every other time the car is pushed.

I have pointed him in the direction of this being a lambda sensor fault but was wondering if anyone on here has had anything similar and can shed some light on what the cause could be?

Your help would be much appreciated.

Thanks,

[Aragorn30d]

the ECU will have logged a fault code, you need a code reader to find out what it is.

[Cerbera9]

Could be boost related, 30FF code, ECU often flag up a code when they don't reach boost target at higher RPM. as previously mention best to check with a code finder.

[zltm089]

I'll put money on carbon built up.

[fabsp]

Thanks for the responses guys.

The last time he had the car plugged in it came up with a lambda sensor fault.

With the carbon build up, would this come up on a fault code machine? Or is it a matter of not knowing until you take the manifold etc... off and physically seeing it?

Kind Regards,

[Aragorn30d]

The EML is coming on. Whatever is causing that fault, WILL be logged in the ECU. Thus, the ECU already knows whats wrong, anyone else is just guessing things from thin air.

Its also unlikely to be a lambda sensor, a failing one of those wouldnt knock you into limp mode i wouldnt have thought.

Its important to use a proper BMW specific diagnostic kit too, so it properly reads the fault codes. Generic ones can sometimes miss things.

[fabsp]

Hi mate,

He is going to take it to get plugged in next week.

It doesn't go into limp mode by the way that's the weird thing about it, literally just the EML, no other symptoms.

I thought perhaps somebody might have had something similar that could shed some light.

Thanks for the help again.

[djgandy]

Originally Posted by fabsp

Hi mate,

He is going to take it to get plugged in next week.

It doesn't go into limp mode by the way that's the weird thing about it, literally just the EML, no other symptoms.

I thought perhaps somebody might have had something similar that could shed some light.

Thanks for the help again.

It can be underboost, where turbos aren't hitting targets. But also it can be a lot of things?
Where are you based? Anyone with INPA will be able to read the codes for you.

[fabsp]

Thanks for the reply, we are based in Greenford in NW London.

Know anybody good around here? He was thinking to take it down to his local garage who do code reading. Not sure about the system they use though.

[Robbie200]

Originally Posted by Aragorn30d

Its also unlikely to be a lambda sensor, a failing one of those wouldnt knock you into limp mode i wouldnt have thought.

I have had exactly the same symptoms as the OP. Fault codes from memory were 2A2B and 2A2C. A reset would last a few days before the EML light came back and limp mode would result at wide throttle opening.

Replaced both precat lambdas and been fine for 18 months

A guess would be excessive lean mixture causing limp (just my hunch though).

[fabsp]

Thanks for all the advice,

He has decided to get a terraclean done? and if this doesn't work (which I don't think it will but I guess getting rid of the carbon build up can't be a bad thing as it's nearing 100,000miles).

Anybody had experience with Terraclean? Any good on direct injection cars? Might get it done myself too.

Kind Regards,

[Aragorn30d]

Hes clearly an idiot then.

The ECU put the light on because it detected a fault.

The ECU has logged what that fault is, and will tell you if you ask it nicely.

Whys he now doing some snake-oil treatment that will do absolutely nothing to fix the problem, instead of properly diagnosing the issue?

Terraclean will do nothing to get rid of carbon on a DI engine. The whole reason the carbon issue exists is because fuel is injected directly into the cylinder, rather than into the intake manifold like on older engines. How is a dubious cleaning agent added to the fuel going to do anything at all to fix the carbon?

[djgandy]

Originally Posted by Aragorn30d

Hes clearly an idiot then.

The ECU put the light on because it detected a fault.

The ECU has logged what that fault is, and will tell you if you ask it nicely.

Whys he now doing some snake-oil treatment that will do absolutely nothing to fix the problem, instead of properly diagnosing the issue?

Terraclean will do nothing to get rid of carbon on a DI engine. The whole reason the carbon issue exists is because fuel is injected directly into the cylinder, rather than into the intake manifold like on older engines. How is a dubious cleaning agent added to the fuel going to do anything at all to fix the carbon?

^^ You need to plug the car in and read the fault. Terrarclean will do nothing if you have a turbo issue, not that it does anything anyway.

[imy]

Agree with above posts. Not sure why all the dicking around. Get the car over to Jason at bwchiptune, he's in Hounslow and knows his shit. The codes will give a good indication of what the issue is. Even if it was carbon build up terraclean will do jack all.

[Sparky68]

O2 sensor can cause 30ff codes at higher revs due to bad fuel mix. Had this for a while on my car.

[djgandy]

Originally Posted by imy

Agree with above posts. Not sure why all the dicking around. Get the car over to Jason at bwchiptune, he's in Hounslow and knows his shit. The codes will give a good indication of what the issue is. Even if it was carbon build up terraclean will do jack all.

Or if you're willing to do a trip to watford area or staines i'll plug it in for you and see what INPA says.

Or do it yourself. £40 for a cable. Probably less than any garage will charge you and you'll be able to see potentially hidden errors for other modules too.

[surrey 335i]

If this is on full throttle at high revs very likely to be 30ff fault code for low boost. Could be a number of reasons for this step one is get a proper scan for fault codes then work through the possible issues starting with the easy/ cheaper ones first

[fabsp]

Thanks for the heads up! The guys at terraclean told him that the process would get rid of all the carbon in a DI engine (intake tracts and valves) using their "intake clean". I was speculative as it didn't make sense how they could do this without taking the manifold off. I'll tell him to save the bother.

DJgandy, we are not far from Watford at all, could we bring it down to plug it in? That would be a big help.

Cheers

[zltm089]

Terraclean won't do fuck all....documented on all the n54 forums.

[fabsp]

Got my mates car plugged in today. Codes that came up :

2F6C - exhaust valve
30FFH/12543 - Exhaust Fume - Low Pressure Side Turbo

2F6C - Someone had unplugged the exhaust flap actuator in the boot, plugged it back in, problem solved (I hope).
30FFH/12543 - From what I have read points towards a boost leak. Anybody have any tips on checking for leaks and the most common places?

Thanks,

[MAN15H]

Some info here about checking for boost leaks:

http://www.n54tech.com/forums/showthread.php?t=13114

[Dann]

My guess would be on wastegates.
Does it rattle when you come down the revs/rev it when warm?