MAF Delete (CDI 2)

[MLFaN]

I'll take all that advice, thanks guys. I have new monroe shocks coming for the front in two weeks...Bilsteins are out of the question for now as I've spent more than the boss likes to hear about...this includes 3k for new injectors...I'm ok with it tho as I'm holding onto it...I did take her to pedders after some research and the alignment helps heaps. The issue from what I've found online is pretty common with mercs of its age. I've got a set of new ball joints for it too so after they go in with the shocks and another alignment I'll see what the outcome is. There is a bit of a slight grab on pulling up, almost like a buckled wheel. It's got brand new wheels and tyres so it's not that. I'm thinking a warped rotor maybe. As you can see I still have a few items to take care of but it only cost 1800 bux...Although I've spent 10k all up...

 

[rayofsunshine]

NOTE: This only works if you have the EGR delete already done from here:
https://forums.mercedesclub.org.uk/index.php?threads/disabling-egr.68928/.
(It could be made to work if you still have EGR, but you may need to put a 470 Ohm resistor between MAF pin 5 and EGR PWM signal at the ECU end.)

• Are you sick of going into limp home mode all of the time?
• Are you having trouble finding a genuine MAF sensor amongst all the fakes?
• Are you burning through expensive genuine MAF sensors at an alarming rate?
• Then you've come to the right place!

I decided to try this mod after a spate of early failures on genuine Pierburg MAFs on some ML270s I maintain. New genuine MAFs here cost $250 a pop, and the best I was getting out of them was 6 months.

But this simple circuit emulates a MAF just fine on my ML270 (and presumably other CDI2 based vehicles as well). All you do is connect a 5k6 resistor and a standard diode in series, between the 5V Reference pin and MAF signal input pin, at the MAF sensor connector (pins 4 and 5 respectively). Then you just leave the MAF sensor unplugged.

The way it works is that it provides a valid MAF signal to the ECU. The MAF signal pin is a high impedance input to the ECU, so a tiny current flows from the +5V pin, through the resistor, then it gets dropped by about 0.7V by the diode, then the ECU sees about 4.3V on the input. This voltage corresponds to a ECU MAF reading of about 540mg/Hub using star diagnostics. This is at the top end of the range expected by the ECU depending on air temp and barometric pressure.
View attachment 54027


This allows the ECU to run without any restrictions due to the MAF reading.

When EGR is activated, the EGR delete circuit comes into play... Now the 20mA or so current flows out of the +5V ref MAF pin, through the resistor, and through the diode, where it gets read by the ECU again, but this time there is a 470 Ohm resistor there from the EGR delete circuit which pulls down the voltage via the ratio between our new 5k6 Ohm resistor and the EGR delete 470 Ohm resistor. This results in a MAF reading of around 200mg/Hub. This reading tells the ECU that the EGR is working as expected and prevents EGR faults from being logged.
View attachment 54029
View attachment 54030


This is the entire circuit, simply plug it into your MAF loom connector and buy yourself a beer or two with the $250 you just saved.
View attachment 54026


I made mine so that the legs of the components were shaped and soldered like the pins on the MAF sensor, so they fit snugly into the MAF loom connector.
View attachment 54028


You can also play with different resistors and diodes if you find it still gives you codes. I also tried an LED with an 3k3 resistor and it worked fine as well. But I switched out for the above because it was too bulky with the LED. The key things are: You need a diode to drop the voltage below 5V when in non-EGR mode, and you need a resistor to divide down the voltage when the EGR is active and its 470 ohm resistor is pulling pin 5 down.

PS. anyone concerned about the job of the MAF on these... don't. Its only there so that the ECU can detect EGR malfunction, this is a requirement of EURO2. The ECU also may or may not have a maximum fuel limit map based on MAF, but that would only normally come into play if the MAF reading was very low, for example a heavily blocked air filter, or blocked CATs. But in that case the MAP/IAT sensor combo will cause the ECU to limit fuel appropriately anyway. One thing is for sure the ECU loves putting the car into limp mode when the MAF sensor fails. This mod prevents that. If you are still worried, know that my 316CDI Sprinter has the same engine and ECU as my ML270, but it comes without EGR from the factory. And hence it doesn't have a MAF sensor from factory either.

Hi Stumo,
I also have a 2000 ML 270 CDI with EGR emulator fitted, I have rigged it with a change over relay so I can test with on or off, when OFF no faults on Star with smoke, when ON P1430-032 but no smoke. I fitted the MAF circuit with both 5.6k and 8.2k and tested HFM-SFI up to 826.7 mg/Hub, 524.1 normal MAF running any further ideas would be appreciated.
Thanks

 

[MLFaN]

Hi Stumo,
I also have a 2000 ML 270 CDI with EGR emulator fitted, I have rigged it with a change over relay so I can test with on or off, when OFF no faults on Star with smoke, when ON P1430-032 but no smoke. I fitted the MAF circuit with both 5.6k and 8.2k and tested HFM-SFI up to 826.7 mg/Hub, 524.1 normal MAF running any further ideas would be appreciated.
Thanks

Hey mate.
What are the colour codes for the EGR delete?
Do you have any pictures?
Cheers

 

[rayofsunshine]

Hey mate.
What are the colour codes for the EGR delete?
Do you have any pictures?
Cheers

Hi MLFaN,
My colour codes are from the WIS wiring cuicuts as below but they do differ for various ML years

 

[stumo]

Hi Stumo,
I also have a 2000 ML 270 CDI with EGR emulator fitted, I have rigged it with a change over relay so I can test with on or off, when OFF no faults on Star with smoke, when ON P1430-032 but no smoke. I fitted the MAF circuit with both 5.6k and 8.2k and tested HFM-SFI up to 826.7 mg/Hub, 524.1 normal MAF running any further ideas would be appreciated.
Thanks

What is code P1430-032 exactly?

So have you been running fine with the EGR mod for a while? Then tried the MAF delete?

The MAF delete won't work if you have an actual EGR valve still connected. There are loads and paths through the circuit that rely on a fixed load on the EGR circuit, which can only happen if you have the mod done full time.

You need around 550mg/hub on the MAF reading normally, which drops to around 200mg/hub with EGR on. If you aren't getting those values then you will cause fault codes.

 

[rayofsunshine]

Thanks I will check that,
P1430 Exhaust gas recirculation Negitive control variation [ exhaust gas recirculation rate is to low. ]

 

[rayofsunshine]

Back again, EGR mod connected and working no smoke with this fault code




Test



MAF mod fitted as below

Test result with both value resistors

 

[rayofsunshine]

Solved

"P1430-032 Exhaust gas recirculation Negative control variation [exhaust gas recirculation rate is to low.]"

The EGR delete fitted was a commercial one by the previous owner and seemed to be working for past 6 Months, however with Stumos advice of the "EGR delete must be fitted" I pulled apart the device and found the 270 ohm resistor was broken and held in place by the shrink tube, I replaced the resistors and now no fault code.
Still got to work on the MAF delete it is still running at 700 plus with 5k6 or 8k2 resistors in place any further ideas are welcome.
Thank's to All

 

[MLFaN]

Solved

"P1430-032 Exhaust gas recirculation Negative control variation [exhaust gas recirculation rate is to low.]"
Is there a good connection between the wires into the MAF plug?
I used 2 pins out of an old MAF. I pulled them out with pliers, cut them to length and then soldered the resistor and diode onto them.
They plugged in perfectly after that.
Maybe worth a try.
Initially I tried the 5kv resistor with no luck then the 8kv resistor....then bam off she went.

The EGR delete fitted was a commercial one by the previous owner and seemed to be working for past 6 Months, however with Stumos advice of the "EGR delete must be fitted" I pulled apart the device and found the 270 ohm resistor was broken and held in place by the shrink tube, I replaced the resistors and now no fault code.
Still got to work on the MAF delete it is still running at 700 plus with 5k6 or 8k2 resistors in place any further ideas are welcome.
Thank's to All

 

[stumo]

Looks like its not dropping enough voltage. try an LED instead of that diode. Or just keep trying higher resistors until MAF reaches about 550. And its supposed to be a 470 ohm resistor in the EGR delete circuit no?

 

[rayofsunshine]

Thank's Stumo, Yes it is 470 ohm in the EGR delete my typo I will try some variations and report the results

 

[Wayfaringjeremy]

Hey Stumo, all.

Just read through your MAF delete thread and had a couple questions. I have done an EGR delete on my 2003 2.7 liter Sprinter using a 2k2 - 1/2 watt resistor between two spaces on the EGR plug. Like this video shows

I don't have any CELs with this egr delete, but my MAF is either bad or causing the van to still run in partial limp mode (runs better but not 100% and unplugging MAF causes it to run great but with cel).

My question is, would my Sprinter require the same 5k6 resistor (I assume 1/2 watt?) with the 2k2 resistor I have in my egr? Or would I need to switch the EGR resistor to a 470 ohm resistor as you mention in your post? Or do I need to use a different size resistor in my MAF plug to correspond to my 2k2 EGR resistor? Thanks so much for the post.

 

[Alex Craig]

Thank you very much for the post and information I have carried this Mod out today after I had blown 2 genuine replacement Maf sensors and it's worked a treat EGR and swirl flap motor Mod as well and now the Maf mod and the car is back to running and driving fantastic thank you again

 

[ApexKek]

I tried this today with my EGR delete in place, on the MAF i get a reading at idle for around 2.3V, when i connect the MAF delete it says around 2.9V... this is not normal i reckon?

 

[Craiglxviii]

I tried this today with my EGR delete in place, on the MAF i get a reading at idle for around 2.3V, when i connect the MAF delete it says around 2.9V... this is not normal i reckon?

Why would you want to delete the MAF or the EGR? One is silly- the engine ECU actually does need to be told rate rate of air intake; the other is illegal.

 

[ApexKek]

I was measuring at the wrong place, beg your pardon. It is actually lowering the voltage too far, from 5.1 to 2.3V with the 5.6kOhm resistor. If it lowers it this much which resistor should i put in instead?

 

[stumo]

Why would you want to delete the MAF or the EGR? One is silly- the engine ECU actually does need to be told rate rate of air intake; the other is illegal.

And I quote from the OP...
PS. anyone concerned about the job of the MAF on these... don't. Its only there so that the ECU can detect EGR malfunction, this is a requirement of EURO2. The ECU also may or may not have a maximum fuel limit map based on MAF, but that would only normally come into play if the MAF reading was very low, for example a heavily blocked air filter, or blocked CATs. But in that case the MAP/IAT sensor combo will cause the ECU to limit fuel appropriately anyway. One thing is for sure the ECU loves putting the car into limp mode when the MAF sensor fails. This mod prevents that. If you are still worried, know that my 316CDI Sprinter has the same engine and ECU as my ML270, but it comes without EGR from the factory. And hence it doesn't have a MAF sensor from factory either.

 

[stumo]

I was measuring at the wrong place, beg your pardon. It is actually lowering the voltage too far, from 5.1 to 2.3V with the 5.6kOhm resistor. If it lowers it this much which resistor should i put in instead?

Use Ohms law to work it out. Or just try a lower value resistor like 4k7.

 

[stumo]

Thank you very much for the post and information I have carried this Mod out today after I had blown 2 genuine replacement Maf sensors and it's worked a treat EGR and swirl flap motor Mod as well and now the Maf mod and the car is back to running and driving fantastic thank you again

Next on the menu is to punch out your cats. Then it will go like a rocket like mine does.

 

[stumo]

Hey Stumo, all.

Just read through your MAF delete thread and had a couple questions. I have done an EGR delete on my 2003 2.7 liter Sprinter using a 2k2 - 1/2 watt resistor between two spaces on the EGR plug. Like this video shows

I don't have any CELs with this egr delete, but my MAF is either bad or causing the van to still run in partial limp mode (runs better but not 100% and unplugging MAF causes it to run great but with cel).

My question is, would my Sprinter require the same 5k6 resistor (I assume 1/2 watt?) with the 2k2 resistor I have in my egr? Or would I need to switch the EGR resistor to a 470 ohm resistor as you mention in your post? Or do I need to use a different size resistor in my MAF plug to correspond to my 2k2 EGR resistor? Thanks so much for the post.

I dont think that Sprinter EGR mod actually works. At least on the American sprinter forum (ROW T1N sprinters didnt get EGR) nobody there has been able to delete EGR using that resistor, and plenty have tried it.

There are limp modes that dont light the MIL. So the theory is that those 0.1% of users that report success with that resistor mod are already in a silent limp mode due to something else. So they dont notice the loss in power due to limp mode because they were already in limp.

AFAIK nobody has gotten a simple EGR delete working on a NAFTA sprinter. They have to flash tune it out of the ECU.