... the fuel system from front to back is new.. new fuel lines, new lift pump, bypassed fuel thermometer new injectors, hardlines are fine. new delivery Valve seals, new shut off actuator (stop lever thingus) there's no way it can be a fuel Delivery issue...the only thing leaking is the front crank seal and the vac pump seal

Pardon the stupid question, It hasnt got a trap ox has it?
My money is still on a sick turbo, does it blow black smoke under full throttle?
Has some one played with the IP controls, maybe adjusted the limiter?

Was there any improvement after the Filters were changed?

When you floor the Pedal does the Kick Down Swithch work drop you to a lower Gear?

no trapox, it has the mod that took it off, Changing the filters saw no improvement.. the kickdown switch works, I dont know if someone played with the IP or not I have nothing to compare it to

The engine will run much higher than 2k. He needs at least 3k to highway cruise at what he quotes.

The alda circuit on the injection pump isolated from the boost effect will present what feels like not only poor power but inferior acceleration. He should normally feel the transition point a little when the boost comes up and the alda starts letting more fuel in to burn. This starts to really occur at about 2k rpm.
Instead he is performance flat in that area and is struggling to get by it. What is painful is he has had this problem so long yet it is so common an issue. You can have boost till the cats come home. With inadaquate additional fuel from the alda control it is absolutly pointless to have it..

Now to be fair the issue could be something else. This area is pretty straightforward to check out and in many cases costs nothing to do. So it moves to the head of any list automatically. Many,many past owners have disposed of these cars for this particular issue.

I have been waiting to see if he will put it in park and setp on the pedal and see if he can (briefly, engne previously warmed up) actually get some highe rpms. He should be able to get up there around 4,000 rpms. And, the above test takes no eqipment if your Instrument Cluster has a working Tachometer.

Figured it out!
 

It's amazing really. it's always the simplest thing! So, Checking the boost Vac lines, I found this (see pic) I jumped the line with some spare line I had around... and needless to say... WOW. Now I can see why they say these vans can boogey! I am Curious, this line went to this little switch on the isolation panel between the fuse box, Brake servo line etc... what's the switch? I'll post a pic of my repair tomorrow. It's too dark now

Overboost protection device I believe.

Yeh...I had the issue too at one point but I guess it was not as bad. My 0-60 was 20+ seconds. Apprently it was common at Benz shops to bypass that Valve. It is the overboost protection valve. There are two simar valves, this was the one towards the inner compartment on the firewall correct?

Mine has been bypassed for 2 years with no problems. Apparently they clog up often...but who knows. And yeh, I had the same reaction when
mine was corrected "Oh, so this is what I've read about!!"

I still have to secure the patch line to the either end as it leaks a little. but it works and that makes me happy. the cloud of Crap that was blown out of the engine the time it kicked in was amazing. nice to know the engine can breathe better now

I'd like to revisit this topic a little more, tyler posted his 0-55 video and it's obvious my wagon is still lacking.. Is there a tutorial that can show me how to go through the connections for the boost signals to the turbo etc.. I'd hate to think my turbo has something wrong with it, I need to check if there's play in the turbine

Here's some notes to some questions that were asked

*There's very little smoke on hard acceleration, however there's some smoke With Rev in park

*Part of the Vac system had fallen apart and I repaired it, but it may still be leaking some, I'll check it and make a permanent repair,

I know there's some banjo fittings that need periodic cleaning, where are these fittings?

Sorry for the long winded post.....

There isn't a banjo fitting on the 603. It's more like a barb with a hose on it on the driver's side of the intake. It still has the overboost valve though, follow the hose.

Take your hose from the intake plenum fitting, run it directly to the ALDA. This should allow good acceleration once you build boost. Be sure that you can blow through the hose and into the plenum, if not then you need to clean the fitting on the plenum (intake).

Check the wastegate linkage on the turbo. I have seen two '87s with this linkage disconnected/loose, which allows all of the turbo's boost to be dumped, no boost and no boost enrichment. This linkage is hard to see, on top of the turbo between the compressor and turbine sections, a metal rod, probably need a mirror on a stick. This can be tested more easily with a boost / pressure gauge at the aforementioned intake plenum fitting. If no boost, check the linkage. If that is all good and still no boost, check that the turbo spins freely by removing the intake rubber boot, and be sure that your exhaust isn't restricted (at the trap-catylist is the usual spot).

If this is all good, check the fuel filters, fuel strainer in the tank, and fuel tank vent (by removing fuel cap). Some have run from a separate fuel source under the hood to ensure that fuel supply is not the problem.

Other than that it could be IP timing, but I'm running out of ideas.