Brun

My car has literally just started holding back at low rpm.
I was driving round with no issues then pulling out of a junction it suddenly held back. I gave it some more right foot and once the rpm got past 3k it went as normal. I took it on some open roads and gave it some and it was perfectly normal in regards to power.
Back in town it is doing the same thing again, but not all the time.
Any thoughts?

fat-thomas

iTrader: (4)

swirl flaps

Brun

Dammit - that's a confident a response.

I held back some detail just to see if they came up.
The car has had a slight oil leak around the inlet manifold and the garage did say that the swirl flaps could be at risk.
I have never done anything about it as apparently my engine isn't a huge risk of impending doom like earlier engines coupled with the fact that the unfortunate fix is a whole new inlet manifold at a cost of £800

Brun

I've done some more searching and my symptoms seem to fall more in line with the failure of the actuator which controls the flaps.
with a little help from You Tube i'm gonna see if i can diagnose this or not.
A cheap fix appears to be blanking the little blighters off although a free quick fix to get me through the next couple of months would be great as a new car is on the cards

ALi-B

iTrader: (1)

Depends on which engine: M57 doesn't always have flaps (depends on year). The N47 has flaps but will have a position sensor to detect any failure/sticking.

Other issues that can cause same symptoms: Sticky turbo vanes/actuator, EGR(s) sticking (N47 has two EGRs, M57 has one), Sensors or wiring relating to Boost sensor (MAP) or airflow (MAF), Vacuum hoses to actuators (EGR, Turbo, swirl flaps etc) and the solonoid valves that control the actuators (blockage/sticking/poor connection etc). And the throttle body (the gears inside the motor can jam intermittently), although that usually puts the engine light on straight away. And finally a leaky boost hose or intercooler or failing turbo (the turbo core itself rather than the VGT/VNT vanes).

After typing that list I may as well just said "could be anything" LOL.

It may have stored a fault code. It won't always put the engine light on or log a message in the check control display as if its intermittent the engine ECU will have to detect a fault on least several full drive cycles (cold start + drive up to operating temp). It does this to stop the light comming on for "one-off" faults.

Brun

It's the 228bhp engine if that tells you anything?

M57???

Brun

CEL light now on with a visit to BMW message to check increased emissions message! Does this narrow it down?

Norman Dog

iTrader: (1)

https://en.wikipedia.org/wiki/BMW_M57

fatscoobfella1

iTrader: (1)

Low pressure pump is common.....

Brun

The car has now returned to normal operation with no holding back or loss of power but still has the CEL.
Gonna have to take it in and have the code looked at.
I suppose at least now I may get a firm answer

Brun

As I said I my last post, the car has returned fully to normality apart from the CEL.
A chap at work brought in his OBD reader which brought up code P0401 which relates to poor egr efficiency.
I've looked at the You Tube vids and the removal and cleaning seems fairly straight forward.
Although the car has done mainly 4 mile journeys for the last 10 months I have made sure it has had a good run down the motorway as often as I can so I'd be a bit disappointed in a way if the egr is all clogged up.
The BMW forums mention some vacuum pipes which may be split/compromised but I would assume that such things would have an impact on performance.
It's just strange to me that the car was holding back significantly and now all is good bar the light

ALi-B

iTrader: (1)

P0401 is just a generic EOBD code ( not a BMW specific code) just meaning there is not enough EGR flow.

The cause can be a few things

Blockage...be it EGR itself, pipes or EGR cooler.

Sticky actuator/valve (likely)

MAF sensor failing (not detecting enough difference in inlet airflow with EGR open/closed)

Vacuum to EGR actuator or solenoid pipe split/leaking

Fault or EGR actuator solenoid (sticking/leaking to atmosphere)

ALi-B

iTrader: (1)

BTW. The holding back may have stopped as the ECU has detected the fault as a permanent one and disabled the EGR system (EGR closed all the time).

It may try and test it out again once every cold start, just to confirm the fault remains. So you may find it'll play up once then behave fine afterward (check engine light still on).

Also whilst this fault remains stored as a permanent fault, the DPF will not regenerate and it will eventually clog up - you will only notice when it's too late when engine performance has reduced because of the excessive back-pressure. So best get this EGR fault sorted and fault code erased before that happens; if the DPF is the version in the centre section of the exhaust its happy days as that's just 8 rusty nuts and bolts to remove to clean it out. If it's the later version where the DPF is on the down pipe it's a lot more tricky and labour intensive to rectify if it's clogged past the point where it the ECU stop you from doing a force regen. I personally prefer to avoid doing a force regen as I have had DPFs fail (melt through the monolith) from the heat involved, and forced regens don't always confirm the car will automatically regen during normal driving (so the car comes back two weeks later with the DPF clogged again).

Brun

Is a sticky actuator easy to diagnose myself?

ALi-B

iTrader: (1)

Ideally I'd use a hand held vacuum pump directly connected to the EGR actuator to manually operate the valve and observe the movement of the valve through the throttle body (or with the valve removed if you want to clean it). Also to ensure the actuator actually holds vacuum and doesn't leak.

Brun

Sounds a bit much for me
Have booked car in on Wednesday - will report back

Brun

And Ali B is the winner
Pressure actuator replaced.
Total bill = £337 most of which is labour.
They bench tested the egr which was fine with no build up of soot so at least I know that I'm doing enough out of town miles for it to sort itself out which was my big concern.
Thanks for everybody's input

chocolate_o_brian

iTrader: (22)

Only just seen this thread. Very interesting even though my Bimmer is long gone.

ALi-B

iTrader: (1)

Glad it sorted

Brun

Dammit - the CEL has returned again with the iDrive spouting on about increased emissions again.
I got my bud at work to plug his obd reader in again but it has returned no codes????
Does this suggest that the fault has sorted itself but I still need the cel clearing???

Either way - place your bets! It's going in tomorrow afternoon to be hooked up to a proper diagnostic machine

Brun

Ok - it turns out to be the same code as last time. The mech has suggested that it could either be a sticky egr (can this be rectified?) or the sensor they fitted a few weeks ago has failed which would be covered under warranty

Dannymot

I would look to get the egr mapped out and a blanking plate fitted .

Brun

Just want a quick fix really as this car will be giving way to an RS3 or A45 in the not too distant future