Anyone disable EGR on '92 2.5 td (602) ? - PeachParts Mercedes-Benz Forum

Marty600 · #1 07-20-2008, 11:46 AM

Advice on proper procedure??? MPG check, before and after? I know on many gasoline engine autos, this little trick can perform wonders for long-term engine life, and help with these insane fuel costs....but I don't know about the diesel. If it is done, you guys think emmisions go way up? TIA...

Jeremy5848 · #2 07-20-2008, 12:35 PM

Not having a 602, I can comment in general terms only, based on my experience de-EGRing 617, 603, and 606 engines. You may see a little improvement in performance and fuel economy but the small improvement will probably be lost in the noise. The big improvement will come from your new-found ability to keep the inside of the intake manifold clean, since you will no longer be dumping soot into the intake. See the first post in this link for pictures of what the intake on my 606 looked like.

You should be able to disable the EGR function by simply removing the vacuum hose from the EGR valve and plugging the hose (a golf tee is often suggested). The EDS "Electronic Diesel System" in your car (it operates the EGR function) isn't smart enough to know that anything has changed. Drive the car for awhile, see if there is any change that you can either notice or (better) measure.

Removing the crossover pipe is easy and will give you an idea of how filthy the inside of your plumbing is. Once EGR is disabled, you can pull the crossover and the intake and clean them out. Once clean, they will stay that way. Have new gaskets available, just in case, if you do this.

There are many threads in this forum on additional work to actually remove the EGR valve and its associated plumbing and control solenoids. One of the members sells a kit of parts to block off the holes created by removal of EGR. You can use the search function to find these threads and have reading material for many evenings.

Let us know what you decide to do and ask questions if you don't understand. We may harass you to use the search function more but that's just us old farts being cranky, don't let it dissuade you.

Jeremy

UT_Tech · #3 07-20-2008, 12:52 PM

Disabling EGR will NOT help with mileage, except at high output. If you cruise under 80mph the improvement will be insignificant and the NOx emissions will go up. Your diesel engine is already very close to optimum efficiency. Your engine will use something like 0.4lb per hp-hr whereas gas engines will get about 0.55lb per hp-hr.

If you want to improve your mileage then you can get significant improvements by tinkering with how much engine power is used. More details can be found here:

http://unwiredtools.com/utcoastdown.asp

Please note that the MPG output of the calculator is scaled for gas engines. To get the equivalent MPG for a diesel engine multiply the MPG result by 1.25 .

Bio300TDTdriver · #4 07-20-2008, 12:53 PM

Yes Dave has done it. You can read about it here.

Jeremy, I don't think you can just plug the vacuum line like on the OM603. I think the EDS will block boost if you do that. MB made the EDS smarter in the '90s.

Marty600 · #5 07-20-2008, 02:47 PM

Jeremy, I had an injector go belly-up a year ago, so I ended up pullng them all and using 'Bosio' nozzles to rebuild them, in other words, I got a look at what you are talking about, tons of tarry/greasy soot were in the intake system...that is another reason I would like to remove/disable EGR. Thanks, marty

Jeremy5848 · #6 07-20-2008, 02:59 PM

Quote:

Originally Posted by Bio300TDTdriver

. . . Jeremy, I don't think you can just plug the vacuum line like on the OM603. I think the EDS will block boost if you do that. MB made the EDS smarter in the '90s.

Rats! OK, then Marty will have to block the inlet or the outlet of the EGR valve (I did both on my 606NA) so that the EDS computer still thinks something is happening but nothing actually passes through the EGR valve.

If EDS is even smarter than that, and can detect that nothing is flowing through EGR, then Marty must do what the '98-99 606 turbo folks do, block the port on the exhaust manifold and connect the EGR inlet to a small air filter or (via a tube) to the clean half of the air cleaner box -- so it gets clean air instead of dirty exhaust. That way, EGR gets to do something and the EDS computer is happy, but only clean air is sent through EGR and into the intake.

Once that is done, Marty can clean up his pipes and they will stay that way.

Jeremy

sixto · #7 07-20-2008, 05:32 PM

Pulling clean air through the EGR valve only works in non-turbo 606s. That doesn't work in turbo 606s. Not that I know, anyway. I think the problem is boost pressure will leak out the EGR valve since atmospheric pressure is lower than mixing pipe pressure.

AFAIK there isn't yet a workaround for the 606 turbo. Maybe there's a solution for the 602 turbo but outside air isn't it.

Sixto
87 300D

sixto · #8 07-20-2008, 05:33 PM

Maybe a little trap oxidizer or trap catalyst between the manifold and EGR valve

Sixto
87 300D

#9 07-21-2008, 01:19 AM

Search, there are working fixes for the 606a EGR.

The 92 is computer controlled so killing the evil EGR will make the computer disable boost. Replacing the vacuum wastegate actuator with a normal boost pressure on will remove all of the computers influence in the matter.

No Diesel should ever have an EGR.

Marty600 · #10 07-22-2008, 01:18 AM

Hmmm, it's apparent now that it's not a truly easy tweak, I read 'Daves' old posts, and that correlates to what has been posted here, replacing the wategate...And yet, UT tech believes the 602 is running at optimal efficiency, considering the excellent MPG the car already gets, I tend to subscribe to this theory... It has always seemed to me that EGR has got to have bad influences on mileage, but I am not an engine mfg., so who knows? Anyway, Thanks for the replies.

Bio300TDTdriver · #11 07-22-2008, 01:25 AM

I don't believe I've read of anyone noticing much of a gain in mpg after installing the blocking plates. The intake should stay cleaner though.

Jeremy5848 · #12 07-22-2008, 02:30 AM

Quote:

Originally Posted by sixto

Pulling clean air through the EGR valve only works in non-turbo 606s. That doesn't work in turbo 606s. Not that I know, anyway. I think the problem is boost pressure will leak out the EGR valve since atmospheric pressure is lower than mixing pipe pressure.

AFAIK there isn't yet a workaround for the 606 turbo. Maybe there's a solution for the 602 turbo but outside air isn't it.

Sixto
87 300D

OK, I stand (sit?) corrected. Serves me right for commenting on a car I don't own.

Wasn't there someone who was working on an electronic gadget to trick the computer into thinking it still had a working EGR?

gsxr · #13 06-20-2009, 12:17 PM

Quote:

Originally Posted by Jeremy5848

OK, I stand (sit?) corrected. Serves me right for commenting on a car I don't own.

Wasn't there someone who was working on an electronic gadget to trick the computer into thinking it still had a working EGR?

Someone did do exactly that, and posted information on this forum, but I can't seem to find it in a search. Pretty sure it was a 602.962 also.