MAF Delete (CDI 2)

[mioba]

IMO parts like MAFS, EGR and anything else are there for a reason.

If it’s broke replace/fix it. Any circumvention is just a bodge job.

If one finds it cost prohibitive, then get a car one can afford to maintain.

 

[stumo]

View attachment 61839 View attachment 61840 View attachment 61841 Well after that diatribe I will get back to the point of this forum MAF Delete. As previously stated I was to try different resistors, so I rechecked my wiring and cleaned it up with new wires no relay but fitted a plug as J911 did in EGR post page 7, worked fine but still low pressure fault as previous.
Then fitted Stumo's delete with 8.2k resistor no faults now all works well but untidy so I cut back an old MAF to expose the pins fitted the parts and sealed in epoxy see pics

That looks pretty good. I worry about having stuff that could work loose inside the inlet tract though. For mine I just mashed the pins inside the broken MAF's socket, so they were out of the way, and kept the MAF in place. Then my mod plugs into the loom plug as shown in OP, and that plugs into the now empty MAF socket.

If one finds it cost prohibitive, then get a car one can afford to maintain.

Thanks your Majesty. I appreciate you are a busy person, but the answer you were looking for is right there in the OP...

MAF is on these cars only to detect correct EGR operation as per EURO2 rules. If the EGR is deleted then you can safely delete your MAF as well. That saves you going into limp mode for no actual reason and having to fork out for a replacement MAF you don't actually need.

 

[LostKiwi]

Thanks your Majesty. I appreciate you are a busy person, but the answer you were looking for is right there in the OP...

MAF is on these cars only to detect correct EGR operation as per EURO2 rules. If the EGR is deleted then you can safely delete your MAF as well. That saves you going into limp mode for no actual reason and having to fork out for a replacement MAF you don't actually need.

You're bypassing part of the emissions system.
EGRs reduce NOx, the gas responsible for creating those nice blankets of brown smog over cities and a major contributor to respiratory illness.

https://www.gov.uk/government/publications/nitrogen-dioxide-health-effects-of-exposure

I'm actually surprised this thread is permitted as it's encouraging others to perform illegal acts.

Well done.

 

[stumo]

You're bypassing part of the emissions system.

Thanks for the bump, but most people think the MAF is a critical part of the engine control system. Which it is on some cars but not CD2 or CDI3 at least.

The "emissions system" could just as easily use MAP and IAT to detect EGR, in the same way it is used for actual engine control on these.

So deleting the MAF on its own isnt illegal. Its the EGR delete that is, so maybe direct your time/effort to that thread.

Or maybe direct it to actual manufacturers who did this on 10s of millions of vehicles, for profit, rather than a few random people just trying to help each other make the most of their vehicles before they end up on the scrapheap.

 

[LostKiwi]

Thanks for the bump, but most people think the MAF is a critical part of the engine control system. Which it is on some cars but not CD2 or CDI3 at least.

The "emissions system" could just as easily use MAP and IAT to detect EGR, in the same way it is used for actual engine control on these.

So deleting the MAF on its own isnt illegal. Its the EGR delete that is, so maybe direct your time/effort to that thread.

Or maybe direct it to actual manufacturers who did this on 10s of millions of vehicles, for profit, rather than a few random people just trying to help each other make the most of their vehicles before they end up on the scrapheap.

In many countries disabling, bypassing or removing any part of the emission control system is illegal. As the MAF is tied to the emissions control it falls under that definition of illegal.

 

[Craiglxviii]

Thanks for the bump, but most people think the MAF is a critical part of the engine control system. Which it is on some cars but not CD2 or CDI3 at least.

The "emissions system" could just as easily use MAP and IAT to detect EGR, in the same way it is used for actual engine control on these.

So deleting the MAF on its own isnt illegal. Its the EGR delete that is, so maybe direct your time/effort to that thread.

Or maybe direct it to actual manufacturers who did this on 10s of millions of vehicles, for profit, rather than a few random people just trying to help each other make the most of their vehicles before they end up on the scrapheap.

This is exactly the same excuse that Mitsubishi tried to use, that led to them being bought out for $1 by Nissan.

 

[stumo]

This is exactly the same excuse that Mitsubishi tried to use, that led to them being bought out for $1 by Nissan.

Mitsubishi are one of the ones that have used MAF for base engine control in the past eg. on their EVO 10. Its quite a dangerous method of control on a turbo engine given how unreliable and prone to dirt MAF sensors are. And Nissan used it on their ZD30 Diesel engines, which is why they self destruct. Thankfully MB did it properly here, and the MAF is actually surplus to requirements. And thanks for the bump.

 

[Craiglxviii]

Mitsubishi are one of the ones that have used MAF for base engine control in the past eg. on their EVO 10. Its quite a dangerous method of control on a turbo engine given how unreliable and prone to dirt MAF sensors are. And Nissan used it on their ZD30 Diesel engines, which is why they self destruct. Thankfully MB did it properly here, and the MAF is actually surplus to requirements. And thanks for the bump.

Sorry, I didn’t make myself clear. Mitsubishi used the argument of “we designed it this way, your laws say it must be done that way, technically they’re pretty much the same and the difference doesn’t amount to much” with the South Korean authorities over 20,000 kei cars. The fallout of that resulted in Nissan buying them out just to get it’s hands on their pickup truck design standards.

 

[rafal1199]

Hey,
I am trying to fit this mod on 2000 W220 S-Class OM613. The control unit it is the same (CDI2). Hooking 5k6 or 8k2 resistor with diode results with immidiate limp mode. 3k3 or 2k2 resistor works but after +30min trip car is getting into limp mode again. I have also fitted EGR mod which is working perfectly fine for 2 years and now I want to get rid off MAF. The MAF readings are:
5k6 resistor - 1200 mg/hub
3k3 resistor - 1600 - 1900 mg/hub
2k2 resistor - 2500 mg/hub
5k6 resistor again - -100mg/hub LOL

 

[LostKiwi]

Why not fix it back to as designed instead of doing a lash-up bodge?

 

[Kev555]

It was a bodge in the first place to fit all this stuff to an engine

 

[LostKiwi]

It was a bodge in the first place to fit all this stuff to an engine

It was a requirement to clean up the decidedly toxic exhaust of diesels.
The bodge was directing the breather condensates into the inlet tract.

 

[stumo]

You need both measurements, one with EGR on 100% duty, and one with EGR off. There is an EGR test in MB star that shows the MAF reading and allows you to switch EGR on and off.

As long as you get a MAF reading roughly in the middle of the green band in star with EGR off. Then and then it drops a bit with EGR on. It should be ok.

What codes did youu get fron the limp homes?

 

[rafal1199]

I will check both values with EGR on and off, thank you all for hints I will post the results

 

[rafal1199]

I will check both values with EGR on and off, thank you all for hints I will post the results

You need both measurements, one with EGR on 100% duty, and one with EGR off. There is an EGR test in MB star that shows the MAF reading and allows you to switch EGR on and off.

I have done some test and results for 3k3 resistor with diode are:
idle - 250-320 mg/hub
egr opened - 600-700 mg/hub
egr closed - 1500-1700 mg/hub

The interesting thing is, when I get preview of read values in HFM-SFI test, the Air mass shows over 1500 mg/hub values and drops to 200 after quick rev.
Odd thing is the value should be lower when egr opened but in my case is higher. After some minutes of trip there is no limp mode but then ECU is not reading values from MAF anymore (0 mg/hub) imo due to too low signal, which triggers limp mode.

What codes did youu get fron the limp homes?

The codes are: HFM plausibilty
MAF signal too low

I will test out adjustable resistor to find the way of its value that will not throw na code.

 

[stumo]

Somethings not right with those readings. Are you sure youve got the +5V pin supplying the circuit? And the MAF signal circuit matches exactly the EGR delete circuit, and the EGR transducer permanently unplugged?

 

[rafal1199]

Somethings not right with those readings. Are you sure youve got the +5V pin supplying the circuit? And the MAF signal circuit matches exactly the EGR delete circuit, and the EGR transducer permanently unplugged?

Yes I have 5v power supply
I manipulated the resistor and found that 10k ohm with diode (voltage drop to 2.8v) keeps readings in green area and it passes the egr test (lowering flow when opened and rising when closed) and HFM reading looks also good.
But I still get 0mg/hub reading after driving a while... I double check EGR mod wiring eveythings OK. EGR is not plugged because I cut the wires by the ECU and transducer threw away (also modified vacuum line).
Like I said the EGR mod been running very well for few years nows the MAF is tricking me

 

[stumo]

Somethibg must be causing that MAF to drop to zero. I think the ECU calculates MAF value by reading the voltage but also incorporating the air temp? So maybe the air temp sensor is flakey? When it does it next it might be worth measuring the voltage at the MAF pin to make sure its still ok to rule out the mod.

I saw in your earlier posted readings you said the MAF was different at idle, than with EGR on and EGR off. But there shouldn't be an "idle" reading, only the 2 readings, the EGR on or off should both be read at engine idle.

 

[darcygoerlitz160]

can the maf be deleted on a om642 engine.
cheers darcy

 

[Tonybris]

I have W211 OM642 with CDI 4, there are 02 MAF sensors with 04 PINs, I measure the plug connector when disconnected and connected to MAF sensors
PIN1 : 12V
PIN2: Earth 0V
PIN3: 5V when disconnected and 2.8 -> 3.2V when connected
PIN4: 5V hen disconnected and 2.3 -> 2.6V when connected
So probably MAF has multi-sensors on PIN3 and PIN4 respectively.
Could anyone advise which PIN is affecting the air mass calculation or both?
The MAF sensor part number is
CDI 0281002695 A6420940148

Thank you