1992 300D EGR req. Most Knowledgable Tech
 

When you plug the vacuum line going to the EGR valve on this engine (1992 602 300D) the electronic boost control cuts boost by opening the wastegate on the turbo. I have heard that airflow meter in the top of the air cleaner housing is responsible for the signal that causes the boost to be cut when the EGR vacuum line is plugged.
I heard that one fellow bypassed the system (EGR abnd Air Recirculaing Valve on fresh air side of turbo)) entirely by installing a manual boost controller which ran off manifold pressure. He also had to install a pressure type turbo wastegate in place of the vacuum actuated wastegate.
Another fellow, who is a bit smarter than I, designed a pressure sensing circuit board, installed a pressure sensor rated at 15 PSI in the manufold and somehow electronically defeated the EGR and air recirculating valve without cutting boost.
Both of these methods seem a bit complex and expensive. (as compared to the luxury that most of you guys have of putting a BB in the vacuum line). Has anyone got any more to add to this subject.

Why would you want to? The EDC control system is engineered
to operate with a EGR system. What could you possibly stand to gain (other than a cleaner intake) by disabling EGR?
Not to mention tampering with or disabling your emissions equipment is illegal.
The 603 and 606 diesels all use either a MAF sensor, MAP sensor,
or both to cross check the efficiency of the Boost control and EGR
systems. Thats why you loose boost when you disconnect EGR.
Thats also how the engine self checks itself for correct EGR control
and monitoring.

I saw someone with a homebuilt "circut board" and a jerry-rigged
map sensor butched into their car. His motor melted down
shortly after from lack of correct boost control and detonation.
Dr.D

I agree - messing around with the EGR on a computer controlled Diesel is a major waste of time.

My 2.5 turbo gets 37MPG on the highway - I doubt you are going to get much more by disabling the EGR. As far as a power increase goes I doubt you would effect the engine output by more that a fraction of a horsepower. Why bother? If you are more interested in speed than power you need to take a look at a gasser.

Just my .02

Tim

I wanted to keep the gunk out of my intake manifold as it has a habit of plugging up the ALDA and boost pressure sensor hose. When I took the air intake duct off leading to the intake manifold it had about a 1/4" of black gooey goop covering it and the intake manifold. I bought the car 3 years ago with 135k on it. It now has 175K. I heard that keeping the oil level at about 1/2 way between the fill mark and low mark minimizes oil vapor entering the intake manifold, which I understand is a major contributor to the goop buildup. Perhaps most of the goop was there from the prior owner who kept it full.
I know what you are saying about leaving well enough alone. It's probably the best advise.

Thanks

Walter, if you still have your '93 300D, you might want to check out this thread... it has details on how you can disable the EGR without losing boost, by converting the actuator to a pressure-type unit.

Doc D, I'd love to hear more about this "melted down" motor. Sounds a lot like an old wive's tale to me. The mechanical IP's aren't capabale of pushing enough fuel to cause a meltdown, even with excess boost, except under the most extreme, bizarre circumstances...

:stuart:

Swap the vacuum actuator for a normal pressure actuator like gsxr did. Disabling the EGR ressults in a cleaner running engine, better MPG and better performance.

EGRs on Diesels are an abomination.