CDI3 EGR bypass mod

Alex Crow · Dec 23, 2011

Yes, had forgotten that most have 12v and 0v from soldered connectors in wiring loom.

The problem with cutting the PWM is that I would expect the EGR valve to be fully open (0% PWM), but maybe not - full open is usually directed with 5% PWM.

Worth a try, if it does leave the valve closed we could use a 2 gang 1way switch, cutting PWM to EGR in one position, and cutting 0v to mod in other position - still one switch, could be wired in control case, and all wiring looking OK under bonnet.
I think the 2.2k resistor would be left in place, and the ECU would be happy with varying resistance between PWM and 12v.

grinich · Dec 24, 2011

As WIS 'says', my situation it is described in attached image (my car is 07/2004). Do you remember mercuxio? :twisted:

I'll probably cut (as wise Alex said) PWM & 0v near the EGR connector sending four wires to ECU box and there prepare the original mod but with a switch in 0v (Is it compulsory to do same with PWM? now it is bypassing Z7/5 node as in previous car versions... isn't it?).

First week of 2012 I'll on holidays

and I'll try it... If I have it all clear :twisted:

BTW, merry christmas for all of you !!!

Alex Crow · Dec 24, 2011

In post #81 I was wondering about the possiblity of cutting the PWM signal to the EGR valve, and its effects.

I was suggesting it may leave the valve fully open, or may do what we want and leave it closed - worth a try as I said.
If it worked, all wires outside the ECU box could be as factory, with the mod switchable.

grinich · Dec 24, 2011

Alex Crow said:
In post #81 I was wondering about the possiblity of cutting the PWM signal to the EGR valve, and its effects.

I was suggesting it may leave the valve fully open, or may do what we want and leave it closed - worth a try as I said.
If it worked, all wires outside the ECU box could be as factory, with the mod switchable.

Ok Alex... before you kill me :mrgreen: two questions, please: when the car ignition is off (key out), the EGR valve is it allways closed 100%? Second: when I turn on the ignition, if I unplug the EGR connector, the EGR valve is it closed 100% allways or maintains it as was before I unpluged it?

I'm drawing the mod for your consideration but I need answer for these questions... (I will apply a LED too). All these questions are for same reason: I don't know the exact form of operation for the EGR valve

Many thanks

Alex Crow · Dec 24, 2011

grinich said:
when the car ignition is off (key out), the EGR valve is it allways closed 100%?
Second: when I turn on the ignition, if I unplug the EGR connector, the EGR valve is it closed 100% allways or maintains it as was before I unpluged it?

1. Yes, always closed with no power, a spring keeps it closed.
2. Closed - see above!

mercuxio · Dec 25, 2011

Mission accomplished.

Hi guys,

Just to update. I've made the circuit and fitted to my car. Success on first attempt. No errors etc.

I did the original version by Alex. (Thanks!) Decided against the LED - Not going to see the box as it's tucked inside the apparatus case all the time anyway. Decided against the switch - Don't think I would want the EGR turned on any time with a switch plus the mod is very reversible.

I fitted the whole circuit into a small 35mm X 50mm ABS tranlucent blue box and connected the wires with tap clips. So the fitments were really easy. See photos.

Also I found out that my car E270CDI 10/03 with a Brabus D4 piggyback does not have the 0v coming from the EGR. Only the PWM. So I just tap on another 0v from the ECU. Unplugged the EGR connector and used a soft hose to hold them together (but not connected). The setup looks neat. The tapping are as follows: -

12v - ECU pin 1/F (red/blue)
0v - ECU pin 2/F (brown)
PWM - ECU pin 90/M (grey/yellow)
MAF - ECU pin 85/M (yellow/white)

By the way, I have the materials to make 10 of these (9 left) as I can only order the components by 10s. So if anyone wants, I can it make the EGR emulator for you for a small fees + shipment. Definitely not 100 quids like in ebay. I'm in Malaysia.

S.Speed · Dec 25, 2011

Well done..
What a neat set up you have devised..
Very impressive.

grinich · Dec 25, 2011

Congratulations marcuxio, I don't understand when you say: "Unplugged the EGR connector and used a soft hose to hold them together (but not connected). " Can you explain it or put a scheme?

I'm preparing it for first week of 2012...:wink: as Alex propoused in post 81...plus LED...

Thanks a lot.

mercuxio · Dec 25, 2011

grinich said:
Congratulations marcuxio, I don't understand when you say: "Unplugged the EGR connector and used a soft hose to hold them together (but not connected). " Can you explain it or put a scheme?

I'm preparing it for first week of 2012...:wink: as Alex propoused in post 81...plus LED...

Thanks a lot.

See photo #2. the plugs are held on by a hose about 1.5 inches long. I do it that way do that dust does not fill up my connectors should I ever need to use them back again..lol.

mercuxio · Dec 25, 2011

Merry Christmas btw.

grinich · Dec 25, 2011

mercuxio said:
... I do it that way do that dust does not fill up my connectors should I ever need to use them back again..lol.

Ok... you hold them together with a 3M ribbon or similar in prevention for the dush but it is not a propper connection (no cut them, no strip them...)...

Thanks again

mercuxio · Dec 25, 2011

grinich said:
Ok... you hold them together with a 3M ribbon or similar in prevention for the dush but it is not a propper connection (no cut them, no strip them...)...

Thanks again

You're welcomed. I wanted to use something that could withstand the heat. It's quite hot at that location.

grinich · Dec 25, 2011

Hi Alex, me again...

After I have read your advices, I think (think) you said something similar to the scheme attached:

Where K1 is a switch 1way whith 2 gangs (K1-1 & K1-2). The LED is added but it is not relevant for the mod. All cables and connectors are in the control case. Only cut the PWM the other are T ed. And the EGR has plugged its original connector and wires.

Is it all ok? or.... :Oops:

BR

mercuxio · Dec 26, 2011

3 things.

1. The K1-2 should be switching between the circuit and the 0v on the EGR unit for it to definitely work. EGR unit 0v cut and tapped here. This was discussed and should be tested out first - Alex can't be sure if the EGR is opened or closed at PWM 0%.

2. You should probably put a diode after R4 & R5 before the tap in by the LED. Otherwise the MAF "might" never have a small v drop when it's suppose to. Can't be sure on this. Again, test it out. The R4 & R5 pair is like a sweet spot Alex discovered that's probably a little sensitive.

3. Probably a typo but your R2 should be 22k instead a 2k2

Alex Crow · Dec 26, 2011

grinich, that is pretty much what I was suggesting, with an addition of a diode/resistor pair (should be fine and have no negative effect) and a typo on the R2 value as mercuxio points out.

If I get chance I will power up a spare EGR valve I have with 12v and 0v to see what happens.
Hopefully nothing, but I suspect it will be pinned open (someone else pointed out that their EGR valve momentarily opens when ignition is turned on).

If it opens, I will try 12v on the PWM as well (100% PWM!) to see if that closes it.
If it does (hooray) we will need a 2g 2w switch to make the mod switchable within the ECU case, switching the 0v on the mod, and switching the EGR PWM between its PWM signal from the ECU, and 12v (100% PWM).

I suspect the valve will be fully open with either 0% or 100% PWM, which will then leave us looking for a simple square vave generator circuit to supply 95% PWM!

Alex Crow · Dec 26, 2011

Just checked it, and plan 'A' will work - cutting the PWM to the EGR valve leaves it closed!
A 2g 1w switch will work, as in post #93, but with 22k resistor R2 obviously.

Kkanuck · Dec 26, 2011

mercuxio said:
By the way, I have the materials to make 10 of these (9 left) as I can only order the components by 10s. So if anyone wants, I can it make the EGR emulator for you for a small fees + shipment. Definitely not 100 quids like in ebay. I'm in Malaysia.

Hi Mercuxio,

Great job on the neat setup..... please quote me price if you would be so kind for one of these to Atlanta, GA USA. I can paypal you payment, etc. Seeing as you have already performed the mod, and have the parts, no sense in me messing with it.

I need it for my 2006 US Spec E320 CDI which I believe is the same as the Euro 2005 spec if I am not mistaking. ( Chassis: 211.026 Motor: 648.96 )

Kind regards,

grinich · Dec 26, 2011

Ok... next week I will try in two cars (E320CDI-2003 & E270CDI-2004); there are two similar mods with switch+LED.

Obviously changing R2 value to 22k (thanks mercuxio), LED and both mods with a switch 1w 2g: in 0v (near the EGR valve for E270CDI) and PWM. Without a diode for the LED (it is unclear its utility at the moment).

Many thanks Alex (BTW, I hope your trials with your spare EGR and the 'new' mod based in a generator of square waves) and mercuxio.

Alex Crow · Dec 26, 2011

grinich, see post #96! Cutting PWM leaves the valve closed, so my original idea in post #81 will work.

Kkanuck · Dec 27, 2011

Does anyone know what this item is in reference to the EGR? http://www.ebay.com/itm/Universal-E...es&vxp=mtr&hash=item1e67d11e5d#ht_1815wt_1413
Is this a mass produced eliminator?

CDI3 EGR bypass mod

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