MAF issue

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bhonok

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Thanks again MEJ. Your logical approach to a flaps issue is both encouraging and convincing. I will go for this. Great advise..
The MAF issue eventually will be resolved. Maybe problem with hot wire is that I run it from battery with all amperage attached. I will see if I can piggy back it on similar power wire running from ECU. Unfortunately my ML 270 CDI is probably the only car of this model here in Panama, so there is no chance to swap parts just to see what works. And Stealership... they will randomly change parts at prohibitive costs. The main thing is the car runs...there is no urgency...
Thanks for a link to another forum I will try it.
 
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MEJ if I can ask you more help. Please elaborate on fitting a resistor for a flap motor . I need more detailed explanation . The motor can be removed after this ???
Also "switched 12 volt supply to MAF' I am not clear how it works and were from I will run this wire?
Thanks
 
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Manifold flap removal

Since you already suspect the inlet port shut off motor/flaps, why not try this cheap option first? Courtesy of Alex Crow, Dman and others.

Inlet port shut off motor delete (CDI2)
________________________________________
A popular mod now, is to disable the inlet port shut off flaps, particularly on 270 CDI (612) engines.
This is usually done because of damage to the flaps from wear and tear, accelerated by EGR gasses.

It is possible to replace the entire manifold, but at significant cost, and some of these cars are old and unloved now!
Even if the manifold is changed, problems can still occur with the actuator motors (M55) jamming and signaling faults to the ECU.
So, how to do without the system...

To remove the flaps is simple, but leaves big holes in the intake manifold.
To plug these holes, I cut short sections of 16mm threaded bar, tap threads in the holes, fit the plugs with superglue, and finally drill and lockwire them for good luck.

With me so far?

But we still have a problem, if the motor is removed, a fault code will be logged, stating 'M55 inlet port shutoff motor signal wire resistance too high'.
Yes, the motor can be left in place and connected to the loom, and if working there will be no fault code.
However, as is often the case, the motor may have heavily worn gears, and frequently jam.
This will log a different code - 'M55 inlet port shutoff motor signals fault through ground keying', which simply means the integrated circuitry in the motor has seen that its mechanism is jamming, and has signalled a fault to the ECU by temporarily grounding out the signal wire.

So, if the motor is worn and jamming, we have a problem, but we do not want to replace it with a new one, especially now there are no flaps fitted.

Getting there now...

So, to cut to the chase, all we need to do to avoid logging fault codes, is wire in a resistor between the signal (PWM) wire and the 12v wire to the M55 motor.I have found that values from 1k to 10k ohms work - 20k ohms is too high.
I have opted for 4.7k ohms on my testbed, and so far all is well - no codes being logged.

I should add that you can buy these mods on ebay http://www.ebay.co.uk/itm/Inlet-port...item1e6a7d237e , but they are rather more expensive than a 4.7k ohm resistor...

Hello MEJ.
Finally I got time to remove flaps from ML270 CDI. Couple of questions.
1. Is it practical simply disconnect the actuator from motor and affix it in a position for flaps to be fully open and leave them where they are. It will save dismantling the whole manifold ????
2. The motor can be completely removed and substituted with 5 ohm resistor???
 

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Hello MEJ.
Finally I got time to remove flaps from ML270 CDI. Couple of questions.
1. Is it practical simply disconnect the actuator from motor and affix it in a position for flaps to be fully open and leave them where they are. It will save dismantling the whole manifold ????
2. The motor can be completely removed and substituted with 5 ohm resistor???

1. Yes, but if a flap is wearing away it could still drop onto the inlet valve (possibly helping bend it). Also, boost leaks around the flap spindles can add up to a running fault if really bad.
2. No, you will need a 5kohm resistor (= 5,000 ohms). I found values between 1k and 10k work.
 
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Flaps removal

Thank you Alex. Now it is clear.
What happens to flaps if disconnected from actuator ? The flow of gases will push them open or shut ? If open, it will be almost the same as removing them aside from risk of them braking off ???
Can you help me with MAF issue that I raised in the beginning of this tread?
I am chasing 12 volt that according to diagrams of my vehicle should come by red/blue wire from ECU directly to pin 2 at MAF connector , and it doesn't
 

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Why do you want to remove the flaps?
If it is because they are worn, leaving them in is a bad idea, as I tried to spell out above.

Why do you need to find the 12v at the MAF sensor?
It is Red/Blue pin2 at Maf sensor, pin11 at ECU plug 4.
 
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flap removal

My car throws a black smoke and there is no power. Code p1189. I was advised by members that removing flaps and servomotor will be beneficial at least in dealing with P1189.
MAF is next issue. It is either bad or ECU malfunction. I checked Red/Blue all the way from pin 11 at ECU to pin 2 at MAF there is no 12 volt and i think it is essential for MAF . Now, with or without MAF car runs the same.
I try to DIY as much as possible there is huge problem here in Panama with parts and mechanics...
 

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If missing that 12v, I suggest you verify all the power supplies to the ECU.
 
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MAF issue.

Thanks Alex. Can you point me to a specific pins and connectors within ECU that power ECU? Or diagram might help...
 
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Hi Alex. All night I was reading discussion initiated by Dieselman (with your involvement) re disabling EGR with shunt fooling MAF that it is still there working... Looks very practical and logical. Members say it improves performans, reduces smoke, even improves MPG. Looks like perfect solution to most of my problems... If I do it, I do not need to remove inlet manifold to eliminate flaps... right??? There will be no gasses ??? Will I still need to shunt out servomotor????
I hope I am not mistaken and these thing are connected...
 

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You have plug no.1 with 6x heavy gauge wires.
They are 3x earths (brown?) and 3x live (green?).
 

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If the flaps are OK, they do not need to be fixed.
If they are badly worn, they do.

Signs of worn flaps on OM612 engine in order of severity...

1. Oil leaking from flap spindles - fairly common, from eg 60,000 miles average, not a biggie.
2. Flap spindle arms visibly lower down from manifold than new - much harder to check, means the flaps are wearing.
3. Jamming linkage, P1189 code, disconnected or broken linkage - suggests flaps are so badly worn they are jamming, stressing the linkage and motor.
4. All the above, with the flap spindle arms comically drooping down at a rakish angle, almost dropping out of the manifold - time to do something quick.

You need to asses your problem, and go from there.
 
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Flaps removal

Hi Alex. I am sorry if I am keeping you too long with my problems. I will check power supply to ECU. Thanks.
About flaps... 3 month ago I dismantle inlet manifold, cleaned it, ( it was not extremely dirty) inspected flaps and motor. All was OK, flaps moving freely and no signs of wear, no problem with linkage either. Installed it back ... still black smoke, no power and codes p1189, p0403, po470. Some members suggested radical repair - removal of flaps and shunting the servomotor. Yesterday I disconnected the linkage and pushed the flaps lever all the way to the right, opening them completely, as an experiment to see if it will make any difference. Test drive has shown a great improvement. More power, less smoke, better acceleration . So there is no way back for me, but only to decide to go all the way braking down flaps assembly ( they are good) or leave them disconnected with servomotor shunted to avoid Codes.
But now there is new twist. I red the last year post by Dieselman about completely disabling EGR and I loved it. In the new light I do not need to deal with flaps, but simply disconnect transducer and install shunt in ECU with diode and resistors. It promises me even greater improvement to my ML 270 CDI.
I wanted to ask you opinion about this procedure,
 

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EGR deletion will work well for you, but will not fix the P1189 fault.

IF the flaps and linkage are fine, then the servo motor must be at fault - but that is a big if, literally.
 
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EGR deletion

Thank you Alex. I will delete EGR as per Dieselman, and I will disconnect and shunt servomotor to get rid of p1189 code. If all works well, then next big repair I will remove inlet manifold and eliminate flaps and all armature including servomotor for good. Thanks again. Boris
 

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Thank you Alex. I will delete EGR as per Dieselman, and I will disconnect and shunt servomotor to get rid of p1189 code. If all works well, then next big repair I will remove inlet manifold and eliminate flaps and all armature including servomotor for good. Thanks again. Boris

You have said that you inspected your flaps not too long ago and they were fine.....mine were too when I looked at 100000km. If they are good, then just disconnect them from the linkage and jam them wide open after doing the servo motor mod. Save you a lot of unnecessary work. Being jammed open, they will not continue to wear, particularly if you do the egr delete mod.
The EGR mod is very worthwhile and eliminates further gunk buildup in the inlet.
 
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flap removal

Hi Oiglie. So nice of you to come on line. You are right there is no need to remove flaps or even servomotor if you are disabling EGR. I have disconnected mines from linkage just to see if it works and the change is significant. I don't know how to jam them and if it is important. Looks like they stay open by default... Eventually I plan to remove the whole assembly just to clear an odd ends..
My next project is MAF or ECU. I need to reestablish 12 volts supply from ECU to MAF. The proper supply line from ECU to MAF is not functioning. There is not 12 volts on pin 2 at the MAF connector.
Will post my progress .
 
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ECU , MAF power supply ML 270 CDI 2001

You have plug no.1 with 6x heavy gauge wires.
They are 3x earths (brown?) and 3x live (green?).

Hi Alex. As you suggested I checked plug #1 with 6 heavy wires.. none of them has voltage whether ignition on or off...with plug out, instrument panel will light, but car wouldn't start. With plug in, relay 11 "terminal 15 delayed diesel"will click and car starts. Relay 14 " comfort" will get warm and relay 12 " terminal 15" as well. I checked both relays they are OK . I switched them over with others and they behave same way.
If plug #1 is the only power supply to ECU then I am at loss, how my car is still running and with no voltage on all 6 wires how it manages to engage relay 11.
These 6 wires ..where are they coming from?
As I have checked the pins in plug 1 ( before I was checking wires in connector) with ignition on they bring 4.5 volts to all 6 wires ground or live... So it appears that ECU supplies power to these 6 wires but why would it power ground wires ...
 
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Test with plug connected!!
 
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Test with plug connected!!

Hi. Plug 1 has 9 positions and only 6 wires :3 green in positions 1,7,8. and 3 brown in positions 4,5,6. Positions 2,3,9,are unoccupied.
With plug connected : green wire pin 8: 12V, green wire pin 7: 12V , green wire pin 1: 0.1V. Brown wires pin 4,5,6, all show 0.1V.
With plug disconnected :all pins 1,4,5,6,7,8. (not wires) did show 4.5V. All tests with ignition on.
 


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