The only function of the computer after this mod is the idle rpm control. The computer can throw computer codes all day will have absolutely no effect on anything. You don't need to wire anything open or such. Just disconnect the vac connectors lines to the EGR and Flapperdohicky (forgot the name). If you want a cleaner install you can remove the switchover valves and such.
REMEMBER to plug off any vacuum lines that goes to the passengers side of the engine compartment. I think there may be a 3-way connector that needs 1 line plugged.

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92 300D 2.5L OM602 OBK #59

Will do. Any particular reason my EGR and flapper would pull full vaccum and shut down the engine? Why is there an open unrestricted vac line into the firewall? When it's connected my egr and flapper do nothing since it's an open line taking the vaccum away. With it plugged Both Egr and Flapper pull full open at idle and at high rev's till the engine dies. I'm just reconnecting after someone diconnected everything. Not sure if the turbo is kicking in or not. Can't hear it spool up anymore and just recently broke my gauges to test it. Seems like the vaccume I'm getting is constant rather than intermitant with engine rpms.

Thanks

Sounds like they've hooked up vac lines incorrectly. It's a vent line. It's just where it goes. Had the same thing.

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92 300D 2.5L OM602 OBK #59

Any other thoughts anyone? I'm planning on tearing back into it this evening. Maybe I'm using the wrong vac diagram and putting things back together incorrectly ? This is the only vac diagram I've found that's even close.(basic version) But it's a dead ringer for what I've got in the system. If you look at the far upper right it shows the filtered (open) line connecting into the rest of the vaccume via a 4 way connection. My system just draws this as an open leak.

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The black tubing is for vent lines to the atmosphere. THe vacuum pump has to suck air into the system, and MB tries to make sure it's clean air by having the vent lines pull from behind the instrument cluster. There may be an inline filter somewhere as well, which keeps dust & dirt from entering the vacuum pump (and therefore the engine, as the air gets sucked into the crankcase).

It does appear you're using the proper vac diagram, but after you delete the emissions junk, you'll have very little vacuum plumbing left. One small line will feed the VCV on the IP for transmission control, the other small line goes to the passenger compartment to operate the climate control air flaps. That's about it though.

Thanks GSXR. That's what I was figuring but something is odd here. The vent line pull air in easily and with it connected both the EGR and Wastegate don't seem to function at all. With the vent line plugged both the EGR and Wastegate pull into full open position at idle and choke the engine out. It seems like the main vaccum line coming from the right side of the engine pulls either a full vaccum or some of the electric selinoids or diaphrams are not working properly. To tell you the truth I'm pretty perplexed at this one. I've never come across this before. Plugging both just removes the turbo I believe so I'm stuck until I can make it manual. I know the vaccum set up is right. I've checked it over three times or so. If the vent line had some resistance it would be possible that the EGR and Wastegate might function as vaccum is increased by RPM's but there is none. Any ideas or testing I can do. Thoughts?

Appreciated.

This may be normal. The vent line is supposed to always be open, to allow air to be pulled through the vac pump. If you block it, the system would build vacuum and actuate vacuum consumers, like the EGR. Note that the vac wastegate is fully open (zero boost) with no vacuum, and when vacuum is applied it closes (full boost).



I'd swap to the pressure wastegate and remove all that junk. In the meantime, just make sure it's plumbed according to the diagram in the FSM. What is the problem/symptom when driving, btw, with everything connected normally?

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Well. After months of reading about it I've finally completed the wastegate swap. It actually was quite easy; but I did run into a problem.

I had attempted to install from underneath. I had recently left the hospital (major surgery) and after two weeks of laying around I decided to try the swap. No matter what I did I could not access the c-clip that held the old actuator in place. Further, though I did not realize it when I started, I was too weak to do the job.

So I had the bolts off the old actuator but could not remove it. I woke up the next day, completely depleted from my attempt the day before and driving a car without boost. After a few more days rest I drove over to my friends business and we put the car on his lift. I started to work on the car when he said, "Whoa! You're still too weak. I'll have my assistant do this for you."

I thought that was great and went inside while the new actuator was installed. It took much too long but finally the car was off the lift and I was driving home. There was one small problem - NO BOOST.

So I spent the next couple of days building up my strength and wondering how badly I had screwed up my car. Finally, at least a week after I started I went to work on the car again. This time I approached the job from the top. I removed all of the vacuum relay/control-units by the air filter and then removed the inner fire wall.

Once the inner firewall was removed it was very easy to access both the top and bottom mounting bolts and the c-clip. I loosened the nuts holding the actuator. While doing that I observed that the lock-nut that held the adjustable length of the new ATP actuator was loose. I readjusted the set-nut such that the waste gate was fully closed, tightened up the actuator and put a pressure gauge on the intake manifold; peaked at 14 psi.

So the assistant who "helped" with the original install had found it difficult to get the wastegate link to connect to the ATP actuator with the original (correct) setting I had given him so he just loosened the set-nut until it was an easy install. Doing so had caused the wastegate to be permanently opened.

I've not driven much since then; still recovering but I notice that surging and other anomalies that use to appear at certain RPMs and certain load conditions are no longer present. I'm glad to have the EGR disabled and to not have the EDS control anything besides the idle.

As always I acknowledge and thank all helpful and considerate members of this forum. I'd like to specifically thank the following:

GSXR
BOBODACLOWN
AUSPUMPEN

Merry Christmas and Happy New Year to All.

TGD

Sounds like you got er going !!! Didn't happen to find a cheaper source for the actuator did ya? You'd think that was made of gold for the price they want.
I'm still fiddle farting with the rought idle I'm having. 280k miles and compression checks out. It's not the vaccum system, new injectors but now quietly rough, finding air bubbles in the pre-filter and some slight diesel residue on the fuel thermostat housing. Kinda thinking I'm sucking air. Have a bouncing oil pressure gauge that lead me to believe I was experiencing a head gasket failure but the idle smooths out at 1200rpm. I think the system is sucking air or something but running out of places to check. I retorked all the lines but nothing helps.

Congrats on the install !!!

I am going to perform this mod for X-mas

Make the shaft shorter.

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92 300D 2.5L OM602 OBK #59

Shoot, I'm trying to remember. This actuator works in reverse of the vac actuator. Normally open is now closed. Which means boost is always available until it builds up and acts upon the actuator. With the rod length longer it wont actuate until the 14PSI/.95 BAR of pressure builds up ( I believe that is the setting of the special actuator). The adjustment allows you to set a lower amount. Up to 91 specs call .85-.95 BAR (12.3-13.7 PSI) and 92-on .75-.85 BAR (10-12.3 PSI). Not sure what a couple additional PSI will do. But I understand that More Air with out an increase in fuel = higher exhaust temps not more power.

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92 300D 2.5L OM602 OBK #59

When my actuator was first installed the shaft was about 7mm too long. This caused the wastegate to always be open which resulted in no boost.

I think the question is, "can the correct length (I believe it is 107 mm but you should check) be set without shortening and cutting threads. Just take the part out of the box and see if it can be set to 107 mm.

If yes and you do not want to cut the threads go ahead and try. If not cut the threads. It's so easy you can just err on the side of caution and go ahead and shorten it or you can not shorten and then tell us if it works.

That would make sense.

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92 300D 2.5L OM602 OBK #59

Super clean motor. Nice work.

Has consideration been made to installing an air to air intercooler? attachment could be made between the compressor outlet and intake inlet. Space is limited in the W124, but perhaps it could be done ?

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85 300D 3 pedal. Current project.
83 300TD (need rear wiper assembly dead or alive)
84 300SD Daily driver
85 300TD almost 400k miles and driven daily.
98 E300D *sold
86 300SDL *sold and made flawless 10 hour journey to new home.