I have been wanting to do this for a while, as lately I have basically no torque at highway speeds. Like the engine can't pull the car against wind resistance. 0-60 around 15s, feels ok around town but is a dog on the highway.

Nope, but there was a noticable difference back to stock boost. 8psi is WAY too low. Car would struggle on the freeway, the extra boost allowed for more fuel as I recall when I had the ALDA.

So now that I have my boost back to stock or just a little better, how do I adjust the fuel coming in? With the ALDA? Someone has already removed the plastic cap on mine and there is a rubber cap covering it now. I am looking for max fuel economy, not max power. Thanks!

ALDA helps with off the line perfomance.

Your economy should remain the same when it's at proper spec.

I would strongly suggest it. It is very easy to do. Took me about an hour to install the controller and the gauge and I took my time. I really noticed the most difference on the highway. When I go up a hill now, the car does not bog at all. The boost goes up to about 10 psi and it just scoots right along. I have a bunch of things I need to do to the car to get it up to the level of maintenance that it needs. I am going to get the "renew" kit from dieselgiant here pretty soon. It should take care of a lot of the small issues.

Quote:

Originally Posted by bgkast (Post 1323340) Did you adjust max load at all? These engines should have an excess of air, so I am surprised there was an effect from increasing the boost.

Increasing boost will increase fueling as the IP is boost referenced. More boost = more fuel-to a point. The overboost switch inline in the manifold pressure (boost) line running from the back of the intake manifold to the IP will close causing a decrease in fuel if manifold pressure exceeds about 14psi.

I would assume that removing/bypassing the overboost switch will allow the IP to continue to add more fuel at higher manifold pressure. This would be a stupid thing to try without an EGT gauge. The other issue that has been mentioned is the temperature of the air exiting the turbocharger at 13 or so psi is already quite warm. Increasing manifold pressure beyond 13 or 14 psi produces diminishing returns as the increase in temperature negates any gain. Time for an intercooler.

RT

Rob, the limit is basically the limit of the ALDA. Once the ALDA reaches it's limit, you can add all the boost you wish and the vehicle won't perform any better.

In my tests with the ALDA, the limit appears to be 12 psi or less with an ALDA that has been tweaked to provide more fuel off idle. Since the ALDA has a fixed range, if the ALDA is used with the setting from the factory, I'd hazard a guess that 13.5 psi might be required to reach the limit of it's travel.

Did you see my thread on running the 603 without an ALDA installed? This is the true measure of the ALDA limit. The rack is not limited by the ALDA at any point in it's operation.

That's in the works, just need to have my spare intake manifold modified.

Even after I intercool I don't plan on turning up the boost too much. Maybe up to 15 psi from the stock 10 psi that I get now when I have a good load on the engine.


I bet your 12 psi test result is on the money. It seems that the MB engineers would want the ALDA to be maxed out for a few PSI before the overboost protection kicks in. If the ALDA has been turned up (like most of ours) I bet it is topped out around 10 psi.

As long as you can build enough pressure for the ALDA to reach full load when you floor it I see no reason to increase the boost levels...If I want more boost and more power I will just put my foot in it.

With an intercooler, you'll be able to adjust the full load of the IP to take advantage of the increased boost.

Without a full load adjustment, a boost level above 12 psi does absolutely nothing.

The ALDA reaches the limit of it's travel. At that point, it does not limit the travel of the rack. Therefore, and additional boost is simply ineffective.

If you go into the IP and increase the full load setting, now you've shifted the curve and more air is required. So, higher boost settings are necessary to prevent smoke and give additional power. None of this is related to the ALDA, however.

A full load adjustment is the plan after I see how much my EGTs drop; then I will increase full load until I am back near stock temperatures. So far I have only been able to get the Exhaust up to about 1100 F pre-turbo.

The exhaust temperature is load and time dependent. These diesels can run much more fuel and put out considerably more power if the time under load is limited.

Naturally, the factory has them set so that you can run them at full load indefinitely. That's why their power ratings are so conservative.

Your 1100F. temperature would probably climb up above 1200F. on a 1/4 mile run, but, it's well within safe limits.

You could turn up the full load screw right now and run it for a limited time at full load. You may have only 15 seconds before it climbs above 1200F. With a pyrometer, you can do many devious things and not hurt the engine.

I noticed that when I had my boost turned up to where it would hit 15psi or so, I would here a clicking comeing from somewhere around the left side of the dash panel. It was a quick intermittant clicking. Was that the overboost valve that is mounted on the left side of firewall working because of too much pressure?

My guess is "yes."

As per Brian,
I like that phrase! ;) Not going to try it, but I like it.;)