Well I finally was able to adjust the wastegate spring on my 617 turbo. I've actually gotten good at removing the cover, and replacing the weird spring. But the truth is, I can tell no difference whatsoever in acceleration off the line. I T'd into the boost feed from the intake manifold, and though my pressure meter maxes at 10 PSI, I was pegging it pretty hard at 4000RPM. I got 9 PSI at 3000 RPM, but only 2 PSI at 2000. Is this normal? I wonder if I need to back it down before I blow my engine...

Should I attempt to now adjust the ALDA to compensate for the added compressed air? If I'm getting over 1 bar of boost BEFORE the switchover, does the switchover valve itself lower the boost before it reaches the ALDA?

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Matt
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1995 E300 Diesel (Die Blau Frau)

The over boost solinoid will open up and bleed off the pressure the ALDA sees above 1.1 bar. This limits the amount of fuel. Off the line performance will remain about the same as boost doesn't start really building until 2500 rpm or so. You must have proper fuel enrichment to make use of the additional air the turbo provides to see improved performance. The rule of thumb is, With a fully warm vehicle, at full throtle under load, at 4000 rpm you should see a slight wisp of black smoke, in the rearview, in full sunlight.

You should get a gauge that will read up to 30psi or so and recheck your boost. Also just incase check to make sure the over boost switch is functioning by applying 12v across the two terminals of the switch blow into one port while pluging the other and air should vent out of the cap on top.

Bob D.
83 300SD
84 300SD
71 220D

Thanks H20. I adjusted my ALDA yesterday to enrich the fuel mixture, and now I can definitely tell a difference off the line. I suppose you're right about the fuel/air mixture; no amount of boost is going to make a difference unless there's a corresponding increase in fuel added. Now I can take off from a dead stop with more confidence, though the mixture may STILL be a little lean. I only opened up the adjustment by 3/4 of a turn, but that helped a lot. I can discern no black smoke anywhere along the RPM spectrum, so I may indeed still have it a bit lean...

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Matt
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1995 E300 Diesel (Die Blau Frau)

Zoonhollis, if you don't mind could you give us an update on how the adjustmentts you made affect your cars fuel mileage?

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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'92 300D 2.5 Turbodiesel - sold
'83 300D Turbodiesel - 4 speed manual/2.88 diff - sold
'87 300D Turbodiesel - sold
'82 300D Turbodiesel - sold

Sure, I can keep you posted on that. I did the adjustment two days ago, so I'm still on the same tank. Slightly under half a tank (on the guage) shows 235 miles. So far, however, my mileage looks to be about the same. I goosed it yesterday from a standstill and clocked just under 13 seconds from 0 to 60. The ALDA tweak sure helps the low end, but has little or no effect on midrange and upper end. But that's okay; that's exactly what I was looking for.

I went to lunch yesterday with three fairly big dudes all piled in my car, and she ripped off the line without hesitation...

...damn I love these cars.

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Matt
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1995 E300 Diesel (Die Blau Frau)

How do you adjust the ALDA?

Speedy,

The best way to answer that is to suggest you do an exhaustive search here on this forum. The REAL mechanics here far surpass my paltry abilities as a diesel technician.

On my 300D, the ALDA unit (which sits atop the injection pump and has a line feeding into it directly from the switchover valve) had not been adjusted previously, evidenced by the black plastic cover over the adjustment screw. I removed this cover with ease, loosened the locknut, and slowly turned the slotted screw in 1/4 increments before test-driving. I ended up enriching the mixture (by turning 3/4 turn CCW), and she drives and accelerates much better now.

Be advised: Roughly one in ten ALDA's are broken when this adjustment is attempted, and there is nothing in the way of a warning. I was willing to take the risk, and it paid great dividends.

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Matt
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1995 E300 Diesel (Die Blau Frau)

In order to adjust my ALDA, I had to remove the small plastic cover, but to access the locknut, I needed to destroy the black metal piece around the locknut. No harm done with this right?