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  #31  
Old 11-13-2003, 11:02 PM
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hmm,ok...so,my next question is this...is it even worth it to go through all the trouble of making(or buying,if theyre available anywhere)all these pieces?

what kind of an impact on performance will this have if i do end up taking it off altogether?....ive already installed a manual boost controller,boost gauge,air intake,adjusted ALDA...and just today i plugged the vac line to the EGR...and i still get no higher than 15 second 0-60mph times....even though im running 11psi of boost...ive read that my car should be somewhere in the 11-12 second range for 0-60mph...im starting to wonder what exactly is wrong with my car....i think tomorrow ill try taking the banjo bolt off and giving it a good cleaning,but surely that couldnt drop my times down by 4 seconds....anyone have any suggestions as to what i might do to get her in the 11-12 second range???

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  #32  
Old 11-13-2003, 11:59 PM
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  #33  
Old 11-14-2003, 12:09 AM
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85drtysthbenz, removing the EGR completely is more for visual impact than function for me. Although, if you think about it, it could help with turbo lag. By removing it, you are taking out a significant amount of space that would have to be filled/pressurized in the exhaust manifold before reachng the turbo.
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  #34  
Old 11-14-2003, 12:11 AM
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OK, let's try to answer some of that:

1- The 81-85 300SD factory spec for 0-60mph is 14-15 seconds or so. The W123 chassis (82-85 300D/CD) should be 13-14 seconds. Only the newer 124 & 201 chassis are capable of getting to the 11-12 second range. First thing I'd check is your speedometer accuracy with a GPS. My '84 reads low - that means I need to time it from 0-57mph as indicated on the speedo, which can translate into almost a full second right there. But your car will never get to 11-12 seconds without propane injection, intercooling, or other significant modifications. All those figures are based on Mercedes factory specs in the Technical Data Manuals, btw.

2- If your EGR valve is in perfect working order, you gain NOTHING by removing it (other than saving a pound of weight), as long as the vacuum line is plugged or otherwised disabled. What can happen is that the internal spring which keeps the EGR valve closed gets weaker with age, or the seat gets dirty, and it lets some exhaust leak into the intake (with soot) and/or will let boost pressure bleed into the exhaust. The cheap method to fix that is to insert a flat piece of sheet metal between two gaskets - that blocks it permanently. Complete removal just makes things neater & cleaner.

3- Your car should produce 0.75-0.85 bar of boost, or roughly 9-11psi. So your boost pressure is good. Make sure the banjo fitting is clean and the signal line to the ALDA is clean. If you have a MityVac that produces pressure, pump the ALDA up to 15psi. If you can't - if it leaks as fast as you can pump - your ALDA needs a new shaft seal. If it holds pressure (or leaks down very slowly) the ALDA is fine.

4- If the line between the intake and ALDA is plugged (or the switchover valve is plugged) that could easily kill your times by 4 seconds. But on an OM617, at 15 seconds, you're already not far from factory spec.

5- Your car should have good power off the line - if not, fiddle with the ALDA some more. You want it as lean as possible without a power loss. In other words, turn it up (richer, CCW) until you can't feel more power, then turn it back a hair. Turning it up more just wastes fuel.

6- Other things that will affect performance are tire pressure, dragging brakes, wheel bearings, clean fuel and air filters, clogged tank strainer, good injector spray pattern, proper injection pump timing, proper valve adjustment, and proper cam timing (adjust with offset keys). Any or all of those items can equal one or two seconds 0-60.


Good luck,
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  #35  
Old 11-14-2003, 03:41 PM
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thanks for clarifying some of that,dave....i must have misunderstood the 0-60 times,maybe it was for a om603 engine...so now i dont feel so bad about my performance...

i cleaned out the banjo fitting and the line connected to it today with some WD-40...that thing was absolutley filthy,almost completely clogged up with crap...the line itself wasnt really bad,but the bolt was a mess...maybe thatll help out some...thanks for the tips guys
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  #36  
Old 11-14-2003, 06:19 PM
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yo

ok, enough of that, back to me

i got my mityvac, hooked it up to the line that was originally disconnected, and i think i tracked down the leak.

there are 2 round, blue vacuum elements between the airbox and the coolant resevoir. one goes to the wastegate, the other to the EGR. the one that goes to the wastegate is the problem, i think. (unless somehow its not supposed to hold vacuum when the car is off)

it has 4 lines coming out of it, 3 from the side, labeled ATM, VAC, and the one that goes to the wastegate (dont remember the label). the fourth one comes out the bottom, and is also labeled ATM. the 2 ATM lines are spliced together.

i tested the element from all 4 lines, and none held a vacuum, however i tested the one for the EGR and it did (from at least the 2 ATM lines)


questions are:
1 what is ATM?

2 how do i block off this element without messing other stuff up (there are so many splices that eventually lead into that element that seem to go everywhere else in the car)

3 if i need to, where can i get a new one of these?

checked fastlane, didnt see it. and i dont think i need one because ive been driving for years with it unplugged from the vacuum.

4 also, could a leak here affect my a/c?

thanks everybody.
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  #37  
Old 11-14-2003, 11:23 PM
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Those round, blue vacuum element are vacuum transducers : they are electricaly variable valve that output increasing vacuum as current is raised.

VAC is the vacuum input : the line should be traced to the vacuum pump of the engine.

ATM is the vacuum waiste to atmospheric pressure : the line should be traced to a small air filter and then to the inside of the car.

The other in the variable vacuum output : on 91 model, it goes directly to the wastegate.

When not energized, no vacuum is directed to the output. Remember that to keep the wastegate closed (and build intake pressure), vacuum should be feed to the pressure control. If the transducer does not operate as it should, you may have no vacuum output and no turbo pressure.

At idle, you should read >4 volts at the transducer's terminal and >300 mbar vacuum (8.9 in Hg) at the output. Voltage and vacuum will drop as engine speed is briefly raised.

The EDS unit controls the amount of vacuum to the boost pressure control depending of engine speed, IP control rod travel (engine load), actual pressure in the intake, air intake and coolant temperature (1991 model).

The EGR system, air flow sensor (MAF) and EDS control unit operates as a closed loop.

This is what I've learned from this forum : when you cancel the EGR operation on those engine, the MAF sensor does not read a decrease in the amount of air admitted when the EGR opens and the EDS control unit interpret that as a malfunction and cuts vacuum to the boost control in order to protect the engine.
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  #38  
Old 11-17-2003, 11:08 AM
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[QUOTE]Originally posted by Denrac

At idle, you should read >4 volts at the transducer's terminal and >300 mbar vacuum (8.9 in Hg) at the output. Voltage and vacuum will drop as engine speed is briefly raised
[QUOTE]

Oh great, now i have to buy a multimeter too!

Quote:

This is what I've learned from this forum : when you cancel the EGR operation on those engine, the MAF sensor does not read a decrease in the amount of air admitted when the EGR opens and the EDS control unit interpret that as a malfunction and cuts vacuum to the boost control in order to protect the engine.
i thought the MAF was befor the EGR though, right on to p of the airbox?

well, thats helpful, but how can i disconnect that transducer alone and not everything else?

thanks
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1981 240 D 185k
1991 350 SD 185k
2006 S 500
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  #39  
Old 11-17-2003, 11:30 PM
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That tread exposes 2 ways to do it : Low Turbo Boost

There is no simple thing as drop a BB in a vacuum hose " la 617" for the 1990-93 602.

Either you invest in a mechanical device to protect your engine from overboost or in an electronic device "to fool" the EDS. Or maybe the simplest is to make sure that everything is attached and workin as it should.
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  #40  
Old 11-17-2003, 11:51 PM
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oh great, french AND canadian!

Denrac, yeah youre probably right. this is starting to get way too complicated. the problem is though, everything is attached, but its not working as it should.

the vacuum transducer that goes to my EGR is leaking vacuum, my transmission is shifting hard and now my a/c isnt working. im hoping that disconnecting it will stop that. if i have to replace it, fine, if i can disable my EGR and not have to buy a new transducer, great. if the part is too $$$ and i have to drive a slow car, c'est la vie!

later
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1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350
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  #41  
Old 11-20-2003, 03:16 PM
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Vacuum Transducer Valve
Part Number 0005450327
$90 to have full power back
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  #42  
Old 11-21-2003, 10:22 AM
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  #43  
Old 11-21-2003, 01:49 PM
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i think you just answered your own question! :p

well, anyway, first i want to get my car running right, then ill worry about messing with it. im not totally sure its the transducer anymore. i thought it was because it was making a slight clicking noise while the car was running and for about 10 seconds after i turned it off. it almost sounds like something is spinning inside, or like it was leaking. well now both transducers are making the noise.

when the car is off, will the transducers hold a vacuum if i plug my mityvac up to the 'VAC' port? because neither one did, can i just unplug them and plug all of the loose ends to see if that will fix the leak?

my vac lines seem to be in pretty good shape, so i dont think that is the problem, could the leak be somewhere else?

is there some other reason my transmission might be shifting hard? i checked the fluid, its fine.

thanks for your help.
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1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350
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  #44  
Old 11-21-2003, 08:10 PM
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update

took my car into the shop this afternoon and got the vacuum thing straighted out, for the most part.

the vacuum leak that was causing the problem is actually somewhere below the airbox, not in the transducers for the EGR and wastegate. so we left them plugged in and plugged of the line that goes down there. Im not sure what the transducers down there do (seems these Germans like to keep the details to themselves) but ill look it up in my SM. the transmission is now shifting very smoothly and my a/c flaps and rear headrests work again. theyre alot better at working that mityvac than i am, but now i at least know how to do it. thers nothing like watching a pro at work.

so now, unlike when i first found that vac line plugged, the EGR and wastegate are functional, but the transducers under the airbox arent. i was hoping this would make the car shift smooth and still be as fast, but no. the car does 0-60 in13-14 sec, which is faster than it was before this whole episode, but not as fast as before i took it in. (maybe the hard shifting was making it faster?).

dont even begin to think this is over...

"You can always tell a German, but you can tell him much!" - sign at Helmut's Merz-edes, Houston, TX
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also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350
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  #45  
Old 11-22-2003, 08:08 AM
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Has the computer been checked for trouble codes?

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