For no special reason,I disconnected the vaccume line going to the EGR on my 126 Diesel, then plugged the hose off with a piece of brass.
I realize that this procedure does not comply with federal emission laws, but I am not worried about that because where I live we have virtually no enforcement or inspections.

My question is: Will leaving the EGR disconnected permenantly do any damage to the engine?
The car seems to have a little more pep with this modification , and I would like to leave it this way.

Thanks,
Bill

__________________
J. William Tarbrake
NY State Dealer 7014303DLU
Registered repair shop R7014303
82 300SD modified for waste vegatable oil
92 300SE 270K miles perfect
79 450SEL (2 tone custom paint for special occations) SOLD
80 450SL
79 450SL 69K Miles FOR SALE
86 Carver 28 Voyager twin 270 Crusaders (SOLD)
94 CARVER 32 Voyager(SOLD)
67 Chris Craft 40' Aft Cabin(twin ford 427 side oilers)

Bill,

I did the same thing to my car when I bought it 9 months ago and have no bad results. Here in Houston, and probably all of Texas, diesels are emissions exempt. Assuming you have a 82-85 turbodiesel, I don't think anything bad would happen to the engine with such a modification. Eventhough I have a copper disk keeping exhaust gas from getting into the corrugated egr tube, I do notice a little oil/sludge in the area that the egr valve bolts to on the intake manifold. I guess its compressed air leaking out of the manifold. Lots of people just plug the vacuum line going to the valve. I am with you on placing a piece of copper between the egr tube and the exhaust manifold because eventually, the tube and valve become plugged with soot and start to make a mess.

__________________
2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
-------------------------------------
'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

Bill,
What you have done can only help your vehicle. Disabling EGR does reduce turbo lag between ~1200-2400 rpm and, thus, improves power in that range. Additionally, by eliminating the cycle of passing exhaust gases back through the intake, you will keep the intake MUCH cleaner. The line that runs from the banjo bolt to the switchover (aniroid) valve, then down to the ALDA, will not get plugged up as easily or as quickly with gunk.

__________________
Chris

'04 ML500 - 53k, Inspiration Edition, Desert Silver
'11 Audi A4 Avant - Brilliant Black
'87 300SDL sold
'99 C280 Sport sold
'85 190E 2.3 sold

Lucky you have a pre '90 model car. I have found on those made after about 90-91 the EGR cannot be disconnected without reprogramming the computer. It cuts boost and fuel when no EGR is present. Aghh!

1995 S-350 137,000 miles

I have a 1993 C250D(iesel) that is not turbo charged and have disabled the EGR valve some 250/280.000km ago. No problems at all (but then again, it is not turbo charged).
I prefer to keep the exhaust gasses there where they belong!

greetingz,

__________________
1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)

MBenz - If you can figure out how to disconnect EGR on a 1995 S-350 and send me the directions--I'll send you a 3 pointed golden star!!

Oldsouth,

I have tried that on an E290 Turbo Diesel as well, but the turbo charged engine suffers a lack of power after the EGR is dismantled.
I can try to collect some additional info on this item to see whether it can be done or not...

greetingz,

__________________
1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)

Thanks MBenz - I'm at the end of my rope on this one.

FWIW;

I don't know if it would apply to the newer MB's, but on a VW TDI, the ECU can be fooled by adjusting the signal
coming from the MAF sensor by inserting a diode in the line, to cause a small (.3-.7v) voltage drop.
The diodes are shorted out of the circuit by a vac. switch which is activated by the vac. going to the now disconnected EGR valve. The diodes are only shorted when the vac is applied, to simulate the valve opening.
The point at which the vac switch turns on is adjustable, and helps to keep the ECU happy.

Of course this is only recommended for 'off road' use only, as it is not legal to bypass emissions equipment.. YMMV

__________________
1985 300D - 190K Miles - 26 MPG on first trip home - getting rust fixed and repainted.
1987 MB 300 SDL - 238K miles - Sold
2003 DC Ram 2500 QuadCab 6 speed, 4x4 Cummins - 82K miles - 20+ MPG
1999 VW A4 Jetta TDI 5 speed - 83K miles - 50+ MPG is easy!

What is the MAF sensor? I don't think this would work on MB. I don't know what is telling the computer that there is no EGR. I installed a plate between the EGR and the intake where the EGR would function but no gases would be recirculated and the computer still cut the power. There is only one sensor downstream in the intake and I think it is just an overboost protection sensor. It cuts fuel when the boost is not right. I don't think it can tell anything about EGR. I even tried plumbing around the overboost protection sensor straight to the thing on the injection pump to bypass the overboost protection with no luck. I think the air flow sensor upstream of the EGR is the culprit. The air flow should decrease when the EGR valve opens and if it does not, then bingo - computer cuts the power of turbo or fuel or both. This is just my opinion and from what I have been able to learn. No service cd on this car yet. Mercedes will not tell me anything either. I have heard the only way to bypass is to reprogram the computer. I am good with computers but don't know where to start on something like this. I don't know even if dealers have the equipment to reprogram the computer. I have a Chevy Silverado that I have reprogramed the computer with a Hyper-Tech programmer though. Make a world of difference!

Well, I guess I spoke out of place here, not knowing if the later MB cars used a MAF sensor or not. I had assumed that the later models might, and thought that this info might be of use.

MAF, mass air flow sensor, on my VW anyway, measures the amount of air going into the engine. This is how VW's ECU knows that the EGR is working, by watching the intake air flow. The ECU is adjusting the airflow to the amount required for engine load and RPM, to keep NOX emission down. If the computer can't adjust the flow to the amount that it computes the engine needs, it will 'throw a code' and illuminate a check engine light.


This is a great forum board, full of information, but it is keeping me up late night reading
For now, I will go back to reading and learning!

__________________
1985 300D - 190K Miles - 26 MPG on first trip home - getting rust fixed and repainted.
1987 MB 300 SDL - 238K miles - Sold
2003 DC Ram 2500 QuadCab 6 speed, 4x4 Cummins - 82K miles - 20+ MPG
1999 VW A4 Jetta TDI 5 speed - 83K miles - 50+ MPG is easy!

Yes Mass Air Flow sensor is what is telling the computer no EGR. Now how do you diode it?

on my 300D and it runs great. The check engine light comes on if the EGR system on the E320 even burps.
'85 300D
'95 E320
'97 CRV

oldsouth,

Recently I have some power problems with my C250D. Every time I start the car it runs good, but as soon as I am driving social (low revs and at a constant mild speed), the car seems to get information to cut power. The car will continue running good, but needs more time to accelerate and the topspeed doesn't go beyond 175 km/h anymore.

I have changed every single electronic part of the engine and have been to the MB dealer to have the computer checked. Since this problem seems to be uncommon, the MB techs couldn't suggest how to solve this.

Anyway,
If the downstream sensor, you mention, is the sensor that is connected to the air intake pipe by a vacuum line...then this sensor does control the EGR! I have disconnected the sensor (replaced it with an other sensor, but without a good result) and my car is running well again (without any low power problems). I have been looking into the exact function of this sensor and found that it IS connected with the EGR and that it DOES control the EGR...

...just some information...greetingz,

__________________
1990 300SL-24
1993 C250D with a minor 600+k kilometer
www.MBenzNL.com(the Netherlands)

Well, for what its worth, I can't say how this would work on the newer MB's but here is a hint..

IF a person were to take a small vac. switch, adjust the switch point to the correct point (about 40-50% of max vac), and attach to the EGR vac hose to the switch instead of EGR.
On the normally closed contacts attach 2 diodes perferably germainium ones (.3-.4.V forward bias)in parallel, back to back,
(more fool proof this way), and splice the whole thing into the line from the MAF going to the ECU. Silicon diodes would give a larger drop, and are easyer to find, but might be to large for smooth operation.

This might work, it might not, depending on your settings of the switch, and how temperamental the ECU is. I know it has worked for some people's VW TDI engines.
Use at your own risk, as you are messing with emissions and the law does not like that much, so use at your own risk.

The car will no doubt feel a little more zippy with the EGR not restricting the flow of O2 to the engine. Also the turbo will spool up quicker in responce to throttle pressure.
I don't think this would be a good thing to do on a gasoline engine, as you would be fooling with the fuel/O2 ratio. And don't gassers have an O2 sensor in the exhaust?
That would probably throw a trouble code too... if EGR was broken.


Drive ON!

__________________
1985 300D - 190K Miles - 26 MPG on first trip home - getting rust fixed and repainted.
1987 MB 300 SDL - 238K miles - Sold
2003 DC Ram 2500 QuadCab 6 speed, 4x4 Cummins - 82K miles - 20+ MPG
1999 VW A4 Jetta TDI 5 speed - 83K miles - 50+ MPG is easy!