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What is the safe boost limit on E39 530d with stock management?

18K views 9 replies 5 participants last post by  Jabo 
#1 ·
Hey guys,

Firstly, can we increase output on a diesel turbo engine simply by installing a manual boost controller?

If so, what safe boost pressure can the stock engine management on the E39 530d appropriately fuel up to on the stock turbo?
 
#6 ·
I guess you could divide the ECU into two parts, the fueling and the boost. The power comes from the fueling, and at any point, it will be injecting a specific amount of fuel based on things like pedal position and torque limiters.
Running in parallel to this is the boost side which is increasing or decreasing boost to reach the levels programmed in the ECU.

The only time you would see more power would be if the ECU holds back a little on the fueling as it might produce some smoke.

eg.

Pedal position asks for x mg of diesel,
Torque limiters will set the maximum mg of diesel to be injected,

At the same time, it will be working out boost levels and reaching y mbar of boost.

It will combine these values and see if x mg of diesel is right for the amount of air measured (more boost means more air)

So as long as it isn't at a torque limiter, and there is enough air, it will inject the same amount of fuel whether you are at 0.8 bar of boost or 1.5 bar of boost.


Removing the actuator and using something else to control the boost is likely to put the ECU into a limp mode, which activates quite a low torque limiter for safety.

Getting more air into a diesel doesn't really do a lot, but it allows more fuel to be injected giving more power without smoke.
 
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