Is it possible to adjust boost & alda on 300D 2.5 (602.962)
 

I want to adjust the boost on my 1991 300D 2.5, but it does not apear that you can adjust it in the same fashion as the other TD Benz's. Any suggestions??

This is all speculation because I do not know exactly how the electronic boost control works on your engine, but here are some ideas that might be worth experimenting or researching.

Does the system control boost pressure based on feedback? If so, you can attain higher boost pressure by fooling the ECU.

If the system uses a manifold/boost pressure sensor, you must somehow decrease the pressure it sees. One way is to install a calibrated pressure leak in the hose that feeds the sensor--making the ECU see less pressure than there really is. The ECU should compensate by increasing boost pressure.

If the system uses an air flow measurement before the turbocharger to calculate boost pressure, you can install a calibrated leak between the metering device and the turbocharger--making the ECU see less airflow than there really is. The ECU should compensate by increasing boost pressure.

Hopefully fuel enrichment is independent of this boost control function, making it possible to obtain more fuel to accompany this increase in boost pressure.

-Joe

Thank you, I think we are on to something. Has anyone out there ever done this?

Any news?

This something?
 

http://www.peachparts.com/shopforum/diesel-discussion/37309-boost-control-install.html?highlight=Boost+control

This might help!

http://www.dawesdevices.com/

;)

Thanks!

I checked out the links as well as utilized the search function, but I can not find anythng for my car.

Since your engine has ECU-controlled boost pressure, you will not be able to successfully utilize simple external boost controllers like the 617 guys... You must either be creative OR find something specifically for the late 2.5 Turbo.

There might be a performance chip available for your engine. I did some misc searches in google and found references to chips for both 2.5 TDs and 602.xxx engines. Since the ECU controls boost pressure, a performance chip would likely just contain instructions for higher pressure.

You can always try the "cheating" route I recommended above. hehehe

-Joe

I was thinking abot it, but I am looking for something more "factory"

Heh heh, I'm not sure what you mean... "factory" implies stock or unmodified... Changing boost pressure is definitely a modification :)

Unless you experiment with one of the "rigs" I suggested originally, your only other choices would be to install a chip OR find a device that connects in series with the air flow meter or manifold pressure sensor and modifies the signals reaching the ECU.

D-chip sells an OM602 chip that boosts power from 122bhp to 149 bhp, and torque from 208 lbs/ft to 262 lbs/ft. This is a HUGE increase in performance for a diesel engine. I don't know if it will work with your '91, but I'm sure they would know... shoot them an email if you're at all interested.

I have searched for ECU-fooling devices and found nothing. I suppose you could adapt an air/fuel ratio controller for a gasoline engined car to your diesel engine, and use it to change the values coming from the air flow meter, etc. But that of course would take some time and money to work out.

-Joe

Who is D CHIP??

They're just one of the many automotive performance software companies...

-Joe

Do you have any information on them or any companies that make chips for the 300D 2.5?

I don't have any specific or first-hand experience. I just did a quick search in google and found a pdf datasheet. The site in in German, but the google-supplied translation was fairly decent.

Other manufacturers are Superchips, Powerchips, etc. AMG or Brabus could possibly have something too.

-Joe

I tried finding d-chip(couldnt) and other diesel tuning companies but they only offer chips for late 90's-current cars. Joe, do you have the web site for d-chip or what search you entered into google? Ive tried everything but cant find them. I am interested in their 300D 2.5 chip. Thanks!

CJ, Honestly if you want to start tampering with the factory specifications on a mercedes diesel like that, sell that darn mx-6 in your driveway and go buy a "Rustang" or something. What are you going to do next, jack up the back end and put cragers on it while listening to molly hatchet or somethng! :eek:

ps just kidn bud. I am curious if it stresses the engine beyond what the factory intended thus equating to worse gas mileage and or longevity..Anybody know, please chime in thx:)

The 602 has a mass flow meter under the air filter and a pneumatic altitude adjuster. The ALDA can be adjusted, but you have to remove it to do so (or remove the intake manifold!).

If you feel 120 hp isn't enough, check all the assorted pressure lines and the overboost switchover valve to make sure you don't have a boost leak before messing about. You are only getting about 90 hp if the boost system isn't working corretly. Remember the shift control for the automatic is also tied into the boost system!

I'd fix the boost system (or at least check it out) before messing around with anything. The electronic control is mostly for idle control, by the way!

Boost is regulated by a pneumatic waste gate -- check that before trying to adjust the ALDA.

A bad air recirc servo can cause you to lose boost into the air filter, too.

Peter