Disabling EGR

[Alex Craig]

Out of interest.. Costing of all that was?

£3.49 for the resistors and diodes online

 

[ajlsl600]

Sounds grand!!

 

[Alex Craig]

Sounds grand!!

The best pictures I found where on page 7 the bloke showed how they are wired and where each one goes the Maf info is on another page if you want it let us know and I'll copy the link for you

 

[ajlsl600]

Plse do. Will print store for the inevitable.

 

[Alex Craig]

https://forums.mercedesclub.org.uk/index.php?threads/maf-delete-cdi-2.178561/

There's a couple of options on there regarding the resistors I've used a 3k and it's work great

 

[ajlsl600]

Ta.

 

[cebrax]

I am sorry if I am wrong, but with that diode MAF sensor connections are useless. This has the same effect of connecting a resistor instead of EGR valve.

That diode will let current only if there is a voltage above battery voltage which MAF will never supply..

 

[CuNii]

Can I also use the 1N4007 Diode?

 

[MLoser]

Hey all, I recently removed all the mechanical bits of the egr on my ML270 as i had the manifold off with the intention of doing the swirl flaps at the same time, but discovered someone had already removed them previously. Anyway I removed all the egr bits and made a blanking plate with the heater hose connection to the head. Put it all back together and left the egr solenoid connected so it didnt throw a code and I could check for leaks etc. The car seems to run ok like this, is there anything wrong with this approach doing only the mechanical without the electronic shunt? As far as I can figure the computer still thinks the egr is there. The car seems a little down on power however I have a leaky number 5 injector to sort too so though this might be causing low power. Appreciate your response.

 

[stumo]

You will be in limp mode. The ECU uses the MAF to detect if the EGR is actually working by looking for a drop in air flow. Which you dont have. This is what the shunt is for. Limp mode is quite dangerous because it greatly effects your pull away from standing start.

 

[MLoser]

It's not in limp, revving to 4k, not stupidly down on power. I know limp well...

 

[stumo]

There are different limps. It will go after youve been at idle for a few mins.

 

[MLoser]

I've driven it about 300km like this, including idle for long periods. I dont get how the maf can know as all of the egr occurs after the maf - the exhaust is fed back to the front of the inlet plenum and there is no electronic monitoring of manifold pressure/flow the maf is post air filter not post egr inlet.

 

[stumo]

Think about it. When EGR is opened, MAF must drop, and vice versa. The ecu actively checks for this during idle.

This physical EGR blockoff was all tried on the ML in the very early days of this mod. It doesn't work.

If yours works then maybe yours already has the mod.

Have you connected star diag and done the EGR guided test?

 

[MLoser]

You could be right, yes now that I think about it that does make sense. Swirl flap delete was done so logically egr has probably been done too. I suspect aside from my leaky injector I may have a boost leak. Only way to check egr delete is done is to unplug solenoid and take it for a drive see if it goes into limp.

 

[MLoser]

I just unplugged egr solenoid and took it for a drive. Limped straight away, wouldnt rev over 2 grand, no boost. So as I mentioned I've mechanically deleted the egr but the solenoid remains in place/connected and it goes pretty well fine. Could it be I have some boost leaks somewhere that are masking the expected difference in flow, causing it not to go into limp? Btw I had every intent on doing the electronic shunt, just found I haven't needed to. Also I dont have star and dont know the guides egr test. But as it sits, the egr is still electronically functioning it would appear.

 

[stumo]

You aren't the first, and certainly won't be the last to think you have a perfectly running CDI. When in reality you are in one of the many silent limp modes the ECU will readily put you into. RPM alone cannot be the determining factor as to limp mode, there are at least 3 different rpm levels for different limp modes.

Its only when you have experienced a properly running example with zero issues that you realise just how grunty these cars are as stock. For example I can get a decent chirp from the tyres on my ML on dry tarmac from a launch (until the yellow triangle of death almost immediately cuts all the fun).

 

[MLoser]

Good to know, I have only ever experienced one type of limp mode on these trucks. And yes I know these trucks well, this is my second one, my first one was a freakishly quick example, 380k on the clock and was treated like **** as an off-road vehicle. After a brief stint with an ML430 I decided to come back the the diesel, albeit a much tidier example than my first. I have done all my own mechanical and mods on both vehicles, including the egr and swirl flap shunt on my previous. Im in NZ so people frown upon these cars a bit over the trusty hilux etc, but I have found once you sort a few of these basic issues they are fantastic motoring.

Stumo, reading through this thread it appears the egr shunt hack using the circuit is killing MAF sensors? Am I better to delete the EGR through the computer itself? I may also get the computer remapped while I am at it.

 

[stumo]

The killing of MAF sensors is just a theory. I certainly didnt want to be replacing them every 6 months until I maybe found one same as my original, so I just deleted the MAF as well.

Since your flaps are gone already. I'd just do the EGR and MAF delete for the cost of a few $ and be done with it.

Then the only thing left that can reduce performance are the CATs.

 

[MLoser]

I have not heard about the MAF delete,can you elaborate? I've done front cat, just rear to sort.