got it this time - egr bypass 606 turbo - Page 7 - PeachParts Mercedes-Benz Forum

KarTek · #1 02-17-2009, 08:57 PM

Quote:

Originally Posted by mdisav

Super Job Evan! I look forward to the finished product.

Here is a question. Anyway to eliminate the MAF entirely and have the car use the MAP? The fuel delivery is probably most determined by the MAP and TPS anyway.

In the 80's the camaro and firebird tuned port injection systems first used a maf system and then used a map system only. There was also a kit to take the existing older maf system and convert it to the map system.

I figured if it was possible, you would be the man for the job Evan!

If the maf could be deleted somehow, bypassing the egr would probably go with the program. Or maybe there is a way to delete the maf and bypass the egr all in one configuration.

Do you think it is possible Evan?

Thanks,

I'm pretty sure that the MAF is just used in conjunction with the EGR for validation purposes. I've been thinking about MAF elimination to go with the EGR delete. My theory is to use a device called a programable voltage regulator (LM317, T0220 case) to supply the ECU with an average voltage in place of the MAF. This theory depends on the ECU not looking for a particular voltage range based on RPMs.

The EGR feed can also be used to modify the output of the LM317 and simulate the effect of the EGR delete circuit.

I'm kind of burnt out on this right now so I'm just going to leave the car as is right now and see how it responds for the next couple weeks. It did well today and now that I have a Scangauge II, I can R&D the circuits about 10 times faster because I can reset codes instantly.

Stay tuned...

mdisav · #2 02-17-2009, 11:01 PM

Great that we are thinking on the same lines. You have been quite the work horse and mind behind this stuff. I know I and everyone else appreciates it!

Relax, enjoy and rejuvenate! Staying tuned...

mundoracer · #3 11-08-2009, 01:06 AM

Quote:

Originally Posted by KarTek

It's actually a pot. Here's the theory of operation of the EGR operation validation:

The EGR transducer is fed a unique 12v from the k40 relay - hot with ignition. (red/green wire in the picture) The transducer is connected to ECU pin 35 by another wire (green/gray). When the proper conditions are met, the ECU makes pin 35 low to activate the transducer and open the EGR valve.

When the EGR opens, there is a corresponding decrease in the flow of the intake air through the MAF sensor which is read as a voltage drop on the MAF signal feed to ECU pin 21. (yellow/white).

Problem 1: You can't just unplug the transducer because the ECU wants to see a load across the EGR transducer power feed and ECU pin 35 or a code will be set.

Problem 2: You can't just plug the vacuum line going to the EGR valve or plug the EGR feed tube because the ECU won't see the desired effect of the voltage decrease on pin 21 and again, you get a code.

So, to tackle problem 1, I first snipped the ECU pin 35 feed and then simply placed a 1/4 watt, 1k resistor inline between that and the EGR transducer power feed to simulate the load of the transducer. Now, that creates problem 2 because the EGR isn't opening and creating the MAF flow reduction.

To deal with problem 2, I needed to simulate the voltage reduction on ECU pin 21 on cue from ECU pin 35. Conveniently, when pin 35 goes low it makes a great place to shunt off some of the MAF signal voltage. I inserted a variable resistor there to make adjustments and find out exactly how much resistance was required in order to get the desired voltage drop. Now that the circuit has cleared all the codes, all I have to do is measure the resistance at the current setting and then swap in a fixed resistor in place of the variable one.

The reason for the diode is that you have two voltages going to the same pin (ECU 35): The <=12v from the transducer feed and the <=5v signal feed from the MAF. The diode keeps the higher voltage from spilling onto the MAF signal feed and altering it's value.

So that, in a nutshell is how it works.

Update - Here's a preliminary schematic:

I just picked up a 99 e300 and I am very interested in bypassing the egr. I have some ideas on another method I wanted to bounce off you... clearly you have given this a lot of thought. Between this being my first post and the fact that I have barely begun to look around this site, I'm not sure if the following idea has been brought up before...but here goes anyways;

What about hooking up an electric air/smog pump to the egr instead of the exhaust pipe? If the pump doesn’t have an internal check valve, it would be easy to put an external one on...so boost loss wouldn't be an issue. Getting filtered air to the pump wouldn't be an issue. The entire egr system could function as designed, but with fresh air. The pump would ideally be wired to come on only when the egr valve opens, to avoid having the pump run continuously. The old egr exhaust feed could then be blocked off. Electric air pumps came on a lot of GM vehicles, so getting one for cheap wouldn't be an issue. What do you think?

here's a thread I found on google about a guy using a electric pump for another reason, but has pictures and the guys states the the pump will push 3psi
http://www.modularfords.com/forums/showthread.php?t=131228

KarTek · #4 03-29-2009, 01:23 PM

Scott,

Here's the schematic of the circuit I'm running right now:

It's been running fine with no codes for over a month now of daily driving in a variety of environmental conditions.

MB Paba · #5 04-03-2009, 06:45 PM

Evan,

Could you give a bit of info to help those of us with the '97 normally asperated engines figure this out? I was able to follow your instructions till I got to the part about the MAF pin 5. The EGR would no longer open but then it set a code for EGR flow. Guess it was looking for the response to the pressure drop. The 97 has a MAP sensor and an electrical connection on top of the EGR valve.

Also, I tried making a block off plate for the EGR but it sets a code. The U.S. version of the 97 has the electrical connector on top of the EGR so is not like the UK version.

Any help would be greatly apprectiated!! Let me know if you want a pic of the EGR or anything.

Thanks,
Louie

michakaveli · #6 04-04-2009, 12:21 AM

Quote:

Originally Posted by MB Paba

Evan,

Could you give a bit of info to help those of us with the '97 normally asperated engines figure this out? I was able to follow your instructions till I got to the part about the MAF pin 5. The EGR would no longer open but then it set a code for EGR flow. Guess it was looking for the response to the pressure drop. The 97 has a MAP sensor and an electrical connection on top of the EGR valve.

Also, I tried making a block off plate for the EGR but it sets a code. The U.S. version of the 97 has the electrical connector on top of the EGR so is not like the UK version.

Any help would be greatly apprectiated!! Let me know if you want a pic of the EGR or anything.

Thanks,
Louie

For our '97 E300's you don't to do anything like on the turbo motors. What I have done and is disconnect the metal pipe going from the manifold, to the EGR and flipped it 180. The longer portion of the pipe is directed toward the firewall with a valve cover breather installed at the end. The shorter end can be mounted back onto the EGR valve. No CEL's. Everything still works as designed. Just need to make a blocking plate for the hole coming off of the manifold. I used a copper pipe end, flattened it and trimmed it to fit.

'97 does NOT have a MAF.

TMAllison · #7 04-04-2009, 02:04 AM

On another forum I saw a MB part number for a blocking plate for the 606.91x.

Didnt pay too much attention to it but Mich. might have saved the link to the thread?

michakaveli · #8 04-04-2009, 02:17 AM

Here it is...

EGR Block-plate | OM606/605/604? non-turbo

KarTek · #9 04-10-2009, 04:35 PM

Sounds great Scott! Nice job using the taps, that's a good idea. One thing I would suggest is to dip/brush your circuit with liquid electrical tape to seal it in and insulate it from moisture and vibration.

If I move on to the MAF, I'll keep you up to date with that progress as well.

Louie,

To get started, you should reverse any wiring you've done to try to duplicate the turbo EGR circuit. Once you do this, we'll get started trying to figure out a system that will work for you.

michakaveli · #10 04-10-2009, 05:42 PM

MB Paba,

I really think you are making this MUCH more complicated than it needs to be for our '97's... I've been running that setup for years now and haven't had a single issue. If you install a decent filter, you'll be fine. The EGR closes above a certain RPM and up to WOT anyway. Watching the operation of the EGR, the valve only appears active while the engine is idling. As soon as the rev's start going up it's closes.

Am I missing something?

scott19_68 · #11 04-10-2009, 09:54 PM

Yes, I would definitely seal that circuit but I don't plan on it being permanent - I think I'd prefer to add some more ECM I/O 'adjustments' before then.

MB Paba · #12 04-11-2009, 08:11 PM

Michavelli,

I guess I may be making too much of it. Just would like to do it best, if possible.

Evan,

I have removed the components so am ready to proceed. I will try to post a couple of pics I took of the EGR and the MAP sensor.

Thanks for taking a look at it!

KarTek · #13 04-11-2009, 10:07 PM

OK, I need to learn a little about the way your car operates. You'll need a mity-vac and a volt/ohm meter.

1. Put a 'T' in the line going to the EGR transducer and use the mity-vac to measure the vacuum with the engine running. You want to use a 'T' because you don't want to alter the EGR operation and set a code at this time. Note the vacuum level.

2. Shut off the engine and pull the 3 wire connector on the EGR valve. Use your volt/ohm meter set to ohms and measure the resistance for the following pin combinations:

1-2
1-3
2-3

3. Finally, attach the mity-vac to the EGR line and pull the same amount of vacuum you noted in step one. Re-test the same three combinations of pins on the switch on the EGR.

Report all six values here.

MB Paba · #14 04-16-2009, 09:21 PM

Quote:

Originally Posted by KarTek

OK, I need to learn a little about the way your car operates. You'll need a mity-vac and a volt/ohm meter.

1. Put a 'T' in the line going to the EGR transducer and use the mity-vac to measure the vacuum with the engine running. You want to use a 'T' because you don't want to alter the EGR operation and set a code at this time. Note the vacuum level. 1.5" at idle. The vacuum went to 8" by just bumping the idle up slightly.

2. Shut off the engine and pull the 3 wire connector on the EGR valve. Use your volt/ohm meter set to ohms and measure the resistance for the following pin combinations:

1-2 3.170"
1-3 3.035"
2-3 1.914"

3. Finally, attach the mity-vac to the EGR line and pull the same amount of vacuum you noted in step one. Re-test the same three combinations of pins on the switch on the EGR.
1-2 3.170"
1-3 3.047 "
2-3 1.96"

Report all six values here.

It sure takes the meter awhile to settle to a voltage, sometimes kept floating. I did measure the results at the 8" point as well. They were:

1-2 3.18"
1-3 2.46"
2-3 2.24"

Let me know if you want further data.
Thanks, Evan!

Olivier · #15 04-21-2009, 06:24 AM

Evan,
here is another happy customer. I send you the mail I received today from another diesel enthousiast person, driving a of course a E300TD. This is great. I didn't do anything yet as I am not really an electronic person but I should look into it properly.
Thank you from me and thank you from DM:
Olivier
I've performed the EGR delete as shown in THIS thread, and it appears to work very well.

It makes sense that the MAF voltage can be dragged down by the EGR Low signal, I just hadn't got round to thinking about it.

I'm not a member of that forum so can you please say thanks to KarTek for me, for putting the research into this.

regards