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7 Series - F01 / F02 (2009 - 2015)
The 5th generation F01/F02 BMW 7 Series flagship forum. The redesigned 7 series leads off the BMW Fxx chassis code, offering an 8 speed automatic transmission and all turbocharged engine options.

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  #1  
Old 08-02-2015, 03:48 AM
Sheriff1972 Sheriff1972 is offline
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BMW N57 EGR / MAF problem?

Hi,

I have an F01 740D, and a problem that i would like to sort out.
The car suffers from what i consider to be poor fuel economy, and a slight hesitation from when you put your foot down.

The car has no fault codes when i test it using Rheingold apart from one that relates to the aircon not being switched on by the DDE due to high engine load detected (code 801222)...

I hooked up my OBD link MX wifi adapter to look at some PID values on the car to check them out.
The only one that i can see that is not quite right relates to the amount of EGR being recirculated back into the engine.

For example, 23% commanded EGR, with a positive EGR error of 39% meaning (as far as i know) that the engine is asking for 23% EGR and it is getting an additional 39% of the 23%, so an additional 9% over what is requested (23 + 9 = 32% actual). The EGR error is always positive, and always by a similar 9%...
The positive EGR error is there right from turning the engine on, so when running both open loop and closed loop.

I do not know what the airflow reading in g/s should be at idle, to check the reported airflow.

I am guessing that this level is not high enough to throw a code, but enough to affect the performance and economy.
With the MAF connected the calculated load is high at idle at around 52% (this is throwing the 801222 code i think).
I unplugged the MAF and started the car, (this disables the EGR down to zero), but the calculated load goes down to around 24% (no air con gearbox in park) which is what i would expect.

I have had a smoke test done, that did not show any leaks.
I am hoping that it not a faulty MAF. It would be lovely to try a known good MAF to see if the EGR error goes away before stumping up for a new one without knowing it will cure my issue for sure.

Any opinions would be welcome.
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  #2  
Old 08-03-2015, 10:59 AM
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tim330i tim330i is offline
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I moved your question to the F01 7 series forum, you will get more help in here.

Tim
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  #3  
Old 08-03-2015, 02:05 PM
Sheriff1972 Sheriff1972 is offline
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Thanks

Thanks Tim,

A few views but no replies.

I guess it must be one of those odd ones...

Mike
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  #4  
Old 08-10-2015, 05:38 PM
stuartjohn24 stuartjohn24 is offline
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Hello,

Did you get to the bottom of this? I know these engine suffer from coking up around the intake and EGR valve, I have had swirl flap position errors and poor fuel economy. Im hoping to clean the inlet manifold out and replace the glow plugs and faulty control module before the winter sets in! I have a lumpy idle and hesitation when cold.

Stuart
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  #5  
Old 08-10-2015, 05:54 PM
Sheriff1972 Sheriff1972 is offline
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MAF arrives tomorrow

Hi,

I had a good play around with INSTA and you can test EGR flow which was spot on according to the readings I was getting. However the MAF reading was off using this same test.

I have ordered a replacement MAF and pre cat O2 sensor. The MAF I will fit tomorrow as its a 5 min job to replace and reset adaptations.

I can't get at the O2 sensor without a ramp so I will have a garage change it. I am sure its not the O2 sensor as the problem exists when the car us running open or closed loop.

If the MAF does not fix it, I am stumped but will decoke the EGR and intake as a last try.

Fingers crossed for tomorrow!!

Mike
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  #6  
Old 08-10-2015, 06:22 PM
stuartjohn24 stuartjohn24 is offline
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Hi Mike!

Fingers crossed!

My intake pipe from the air filter to the turbo inlet was split severely! I replaced it but ever since I've had MAF errors, from memory air mass calculations are incorrect based from exhaust pressure etc... and exhaust pressure value implausible or out of range etc.... will have to investigate!

Let us know how you get on!

Stuart
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  #7  
Old 08-11-2015, 12:29 AM
Sheriff1972 Sheriff1972 is offline
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Hi Stuart

Interestingly the car threw a code that related to the exhaust back pressure. I changed that sensor thinking that would solve the issue. Alas not. The DPF is fine and regens as normal.

Have had a leakdown test done and this did not show any leaks either.

One more thing that points me to the MAF is that I logged the air mass reading whilst driving. When I put my foot to the floor, the car would jolt like the car had a gearbox problem. Actually, the air mass reading spiked sharply downwards before climbing upward causing the jolt. The O2 sensor reading also went low at this time.

Hoping that in changing the MAF I will be happy once again. Garages say the car is OK as no fault recording in the computer...

Thank God for forums!

Cheers

Mike
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  #8  
Old 08-11-2015, 01:05 AM
stuartjohn24 stuartjohn24 is offline
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Hello Mike,

Sounds similar to mine, I haven't changed it yet as I'm not 100% sure it's faulty and the DDE is mis diagnosing it!

I bought the car from a commuter in London, only ever driven round the city and the DPF had not been regend in some time. Error codes were exhaust back pressure too high, DPF heavily loaded etc... A 200 mile run has cleared that up though and haven't had the errors relating to the DPF for over two months.

I think the MAF may be shot on mine, seems to have started misbehaving ever since I changed the intake pipe between the air box and turbo, now the engine is getting the correct amount of air it seems to have detected the fault, or its coincidence and bad luck which is usually the latter in my case!

I haven't taken and readings when I'm driving, the only symptom I have is the transmission does not seem to engage properly when pulling away at slow speeds, feels like just the fluid coupling and no torque converter lock up is occurring until you get to about 5mph. It does this more often than not.

In sport mode it's fine!

The problem before was sluggish acceleration, hesitation and a general lack of power when simply driving low speed up hills and things coupled with a loud suction noise.

This turned out to be the intake pipe, all symptoms have cleared up now but caused these others which don't bother me so much but wouldn't mind sorting it sooner rather than later!
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  #9  
Old 08-11-2015, 01:47 AM
Sheriff1972 Sheriff1972 is offline
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If you send me a PM, i will send you the N57TU engine document. Very interesting read, and tells you what sensor impacts what. I would send a link, but i cant remember where i originally found it.

Will report later today when i have changed the MAF and reset the adaptations, driven and measured the engine load.

Cheers

Mike
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  #10  
Old 08-11-2015, 02:40 PM
Sheriff1972 Sheriff1972 is offline
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Well, its not the MAF.
The new fault code relates to the DPF being loaded with soot. Ista code 245700.

I checked the exhaust back pressure. Just about in the maximum limits.

I cleared the fault, and forced a regen of the DPF.

Exhaust back pressure is now fine.
Still has the high load at idle, and high EGR error...

Could it be the EGR itself with a fault?
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  #11  
Old 08-11-2015, 04:26 PM
stuartjohn24 stuartjohn24 is offline
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Hi Mike,

Sorry to hear that, sounds like it could be an EGR issue, may be worth taking it off and visually inspecting it, I don't think its hard to get to, its right at the front on the top of the engine.

How many miles has the car done? Mines just clocked over 117k.

I am interested to read the document, I will PM you.

Regards

Stuart
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  #12  
Old 08-14-2015, 11:38 PM
Sheriff1972 Sheriff1972 is offline
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A quick update. Forcing the regen with ISTA has transformed the car. Pulls like a train and very responsive now. The aircon fault code (801222) has not (yet) returned. I am guessing that as my car has high mileage, it may have been subjected to partial regens in the past or just a gradual build up. If I had done thus before I could well have saved a few quid!!
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  #13  
Old 08-18-2015, 01:43 AM
Sheriff1972 Sheriff1972 is offline
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Update on this one. The 801222 aircon error has returned.

Car still pulls really well, but the EGR error percentage is still present.
I found a very interesting thread on adjusting the EGR in INSTA.

It is located in:
service function
Engine
Diesel Fuel Electronics
Adjustment functions
Exhaust Gas Recirculation.

You can adjust this value between 0 - 1.

I came across a post in a different forum that details another 'feature' of my car. The fact that it can sometimes jerk when accelerating hard on the mororway. At first i thought it was a gearbox issue, but it could all be tied into this excess EGR.
Thread is below.

http://forum.bmw5.co.uk/topic/90449-...alve-with-dis/

Interesting part...

This was a service note or bulletin found by a guy on BMWland

"Whilst cruising at higher speeds, typically on the motorway during constant throttle, there is an intermittent jolt like a misfire. the jolt / misfire / hesitation occurs once only.Typical speeds under which the complaint is present are; 1800 / 2000 rpm @ 60 / 70 mph
During cruising, EGR regulation takes place;- typically when re-applying the accelerator pedal. The actual air consumed by the engine increases but the measured value (actual value from HFM) does not rise proportionally in order for favourable fuelling to take place, this is because the EGR is open and an element of unmetered air negatively effects the calculated. The engine hesitates briefly as a result.

In the event of complaint, carry out the following;
- Adjust the EGR, adjust rate of fresh calculated during EGR to +40
- To do this use the service function of the DDE, adjust it by adding the value 40
- End with programming the DDE using the option in the ABL
- Following successful manipulation, let the vehicle assume sleep mode and then check the status of the EGR by entering the test module once more to ensure the value has taken place before carrying out a thorough road test.

Carrying out the above procedure does not constitute a fault with the engine as the wear
characteristics of the engine and ancillaries may necessitate the need to adapt the DDE running parameters accordingly.

It should however, be noted that the air and fuel system should be fault free prior to
adopting such a change.

I wonder if adjusting this value on my car will fix the EGR error percentage....

Will be testing today.
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  #14  
Old 08-28-2015, 04:19 PM
Sheriff1972 Sheriff1972 is offline
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Well, I had the EGR changed for a new one today, and the EGR error percentages stay the same. Running out of ideas now...
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  #15  
Old 05-16-2016, 12:38 AM
artiras artiras is offline
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Hi, did you get to the bottom of this?
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  #16  
Old 05-16-2016, 12:48 AM
Sheriff1972 Sheriff1972 is offline
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Hi,

Yes I did! Thankfully I have INSTA.
I had been looking at the car and different sensors reported problems from time to time and the car just wasn't very quick.

There was one clue that I had misinterpreted. I kept getting a low voltage warning for the DDE. Voltage lower than 9V for more than 69 seconds.

I unplugged the cables from the DDE. There was a thread of cotton from the wrap that covers the wires trapped under the connector!

It would have been like this since the car was built and I spent loads of money changing various sensors with specialist garages, before I got to the bottom of it.

Without INSTA I would never have gotten to the bottom of it.
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  #17  
Old 05-16-2016, 12:54 AM
artiras artiras is offline
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Wow, I have noticed you have changed half the engine! Lol
I am experiencing similar problem, EGR was cleaned but error still comes up. RHEINGOLD advises to change MAF sensor, so I might got to give it a go. Have you ever cleaned MAF sensor? I have read some mixed reviews about procedure. My car is still under warranty (not manufacturers), but they are bastards to pay anything out - already declined one claim!
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  #18  
Old 05-16-2016, 03:14 AM
Sheriff1972 Sheriff1972 is offline
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I certainly learned the hard way.

It was a stupid build error, but had three garages could not fix it. I was relieved in the end.
MAF cleaning can be done, but i would say it really depends on the symptoms you have, and the full errors you are getting from ISTA before doing it.

If your can has the N57 engine i can send you the white paper on it and it explains how it works in quite simple terms and gives you ideas on what to check.

The EGR passed using INSTA, but i could see (and feel whilst driving) there was an error as reported by my little OBD device.

Dont get me started on3rd party warranty companys. Momentum warranties appear to be a scam...
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  #19  
Old 05-16-2016, 04:23 AM
artiras artiras is offline
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Yes it is N57, fault is EGR controller - but after running tests it says that there is too big difference between air intake and air calculated. I had EGR cleaned by garage and fault disappeared for a day. Management is on most of the time, but sometimes might disappear for a bit. Once it did spit some extra faults as per pic, but never came back on again after clearance. Click image for larger version

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  #20  
Old 05-16-2016, 04:24 AM
artiras artiras is offline
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If fault is not showing on the dash, you can feel like a little hesitation from the car / lose of power for a sec and it comes back on again.
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  #21  
Old 05-20-2016, 04:03 PM
CJ745NZ CJ745NZ is offline
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You may have an air leak after the MAF sensor so you are getting unmetered air.

There is a rubber flex at the end of the plastic piece that the MAF sensor is attached to where it goes down and into the inlet manifold. It is 3" diameter. Check that hasn't got cracks in it. Also immediately behind that there is a vacuum hose that attaches to where the flex hose goes in. It goes up to just behind where the Oil filler cap is. The seals fail in there if too much vaporised oil passes through it. To check for leaks, have the engine running and just squirt some soapy water at the connections. If the engine reacts then you have found the leak.
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  #22  
Old 05-22-2016, 07:08 AM
artiras artiras is offline
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Thanks all for all the advise.

I had a good play round today to see if I can get to the bottom of the issue.

1. MAF was playing up, but I have took it off gave it visual inspection (all seems good) put it back in suddenly decided to work again.

2. 3" hose is fine with no visual damage or cracking.

3. Vacuum hose seal is perished pretty badly, was literally falling to bits when I took it off. I takes are full of oil. Any idea for the part number of this seal? (Please see the pic bellow)

MAF all back and running I have ran functionality tests on EGR It self.

Tests results are very inconsistent! I have ran it numerous times and keep getting either ok or not OK.

Any idea why these are so inconsistent?

I have attached some pics to give you an idea what readings I was receiving. Theses are so different every time.

Fault it self still persists, think there might be actual cause to change EGR or map the bloody thing out ;/

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  #23  
Old 05-22-2016, 04:50 PM
CJ745NZ CJ745NZ is offline
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Part number for the hose is 13 71 7 803 842.

BMW parts list is here http://bmwfans.info/parts-catalog
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  #24  
Old 05-22-2016, 10:48 PM
artiras artiras is offline
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Thank you
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  #25  
Old 11-06-2016, 08:02 AM
Sheriff1972 Sheriff1972 is offline
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I have a form of OCD where i need to put my car on INSTA once in a while to make sure that all is well.

I kept having the DDE throw the blocked DPF codes. It was pretty bas as i could not force a regen to start, but a quick Italian tune up sorted that and i forced regens, and thought no more about it.

A month or so later (after mostly motorway miles) the DPF once again was reported as being blocked. This time it gave me another clue... Error 244C00 - Charging pressure control, high-pressure stage, control deviation: Charging pressure too low / positive control deviation. This fault stops the regens from happening.

This relates (if i am right) to the small turbo, with low load and low speed.

INSTA points to the VAC hoses so will have them replaced tomorrow and see what affect this has.

Fingers crossed!
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