Lda adjustment thoughts, ideas, and questions.

[bbob203]

So I'm still getting my turbo pump on my eco engine dialed in. TOnite I was messing with it to see if I could determine the exact time the Lda kicked in by turning the throttle by hand and holding at 2000 rpm and removing the smoke screw and manually pushing the boost pin down to see if the RPms would rise without me increasing the throttle. It didn't do what I had thought.. Can someone explain why my logic is flawed here? Another question is in order to get my max fuel screw adjusted for optimal performance and economy would it be advantageous to set it to slightly smoking on full throttle with the Lda boost line disconnected from the pump and plugged? I currently have my boost bin set to its most agressive position and the smoke screw just barely engaging the pin. I also filed down the nylon washer that is on the boost pin to allow it to sink a little further down. Has anyone ever totally removed that piece? I also have my star wheel turned up about 4 turns to increase the pressure on the diaphragm to keep the Lda from engaging til slightly later in the game which seems to be helping remove excess smoke but still give me about the same acceleration.  Some folks have told me not to mess with it as vw stock settings are fine for what I want but my thinking is that this pump was set up for a different turbo. Comments, critiques, questions and pointers are all appreciated.  

[theman53]

Nope, you need load to really adjust. The turbo will not make boost 100% according to RPM, it is load plus RPM. The spring tension is pretty much correct if it is what I am thinking.
Basically, you don't want to disconnect the LDA boost tube. If you smoke with no LDA imput you will smoke more with it. The spring will help control when it comes on under boost. The ramp will control how much fuel it dumps under boost. The nylon washer and the adjustment on top the LDA are basically a head start to pushing down on it. Same thing boost will do, but without it present. This is helpful if you want the biggest part of the ramp, but the main screw turned up is a bit much on top so you give it a bit more with the smoke screw on bottom.
IMHO the best way to do it is to have a light grey haze throughout the entire RPM range. Less or none in the winter here where it is less than 30F as in the summer it will change. It did for me anyway. Then leave your right foot up from the floor of the car and you will do well and get better mileage.

[8v-of-fury]

No matter where any of the settings are set, you will receive the same mileage when staying out of it and just cruising.

They do not change the amount of fuel 4 cylinders totaling 1.6L of displacement needs to maintain a certain rpm.

With my Rover pump set up for full on gang-bang-o-rama, I can cruise 95-100km/h in 5th by barely resting my foot on the go-go pedal. About 1/8 of its travel to maintain this speed. Up hill? I gotta put down another 1/16th of an inch..

You could put a Bosch VE 14mm injection pump on there (hypothetically speaking), cruising it would still net you the same economy. Being that there is no throttle plate (I assume you know this ) RPMS are directly linked to the amount of fuel injected. Inject more fuel they go up, let off and coast in gear little to no fuel is injected.

This is why diesels generally see no change in mileage with heavy performance gains. Direct Injected actually sees benefit to larger injectors in more ways than just power. They also gain efficiency, thus improving miles per gallon. The ability to inject fuel quicker in the injection process makes more use of the fuel injected.

The little pin that rides on the boost pin is only used when load fueling. Here is a scenario, you mash the go-go at 1450RPM. Wit ha properly setup pump, it will not blow black smoke. It will however raise the rpm's as quickly as it can with no boost present. Effectively an NA diesel with a huge exhaust restriction. As the boost rises (we'll go 1 psi at a time for easy learning) each psi of boost pressure pushes the boost pin down in its bore x amount of movement. The little pin that rides against it is being pushed by the internal throttle, but is being restricted because the boost pin has not moved down allowing it to move yet. Boost pin moves down psi by psi, and millimeter by millimeter the internal throttle is allowed to increase because the small pin riding the boost pin has moved out of its way on the slope and is now allowing fueling per boost. You set the amount of on boost fueling by turning the boost pin to whatever slope you desire. I would leave it at the steepest setting, because in the end.. it all depends on your right foot.

The screw on the very top, the "smoke screw" does the job of off boost fueling coupled half-and-half with the star-wheel. If you have turned your star-wheel down so that the top pin just now only touches it the top of the boost pin then you have effectively added more fuel before boost picks up.

I generally bottom out my star-wheels, use an AAZ boost pin spring (half as tough as the 1.6 pins.. pushes down with less boost.. more fuel QUICKER!), and have the smoke screw just touching the top for ease of adjustment later.

[libbydiesel]

The LDA only comes into play when the accelerator lever is moved to the point that the control lever assembly contacts the lever coming down from the LDA.  It has no effect on the first part of accelerator lever travel.

My preference with tuning is to have the pump set up so that it does not put out any visible smoke under any conditions but is able to fuel right up to the point that just a tad more fuel would result in smoke.  I find this results in the best balance of fuel economy and power.  To get it tuned well, initially set the max fuel a little high so that when you initially stomp it it lets out smoke.  Then watch as the rpms and boost increase.  If the smoke decreases as boost comes up, then adjust the rotation of the boost pin to be more aggressive and decrease the tension of the star wheel.  If the smoke gets more dramatic as boost increases, then do the reverse.  Once you get the off-boost and on-boost fueling matched well, reduce the max fuel screw until there is minimal or no smoke under full pedal.  That's my personal preference.  Second best, IMO, is to set the boost pin at a less aggressive angle and increase the max fuel a little.  This results in more smoke off-boost but once boost rises the smoke clears.  You end up with faster boost response at the expense of wasted fuel and emissions.   

[bbob203]

hmm so basically the less tension on the spring the more it allows boost to build faster wich then allows the lda to do its thing. So inherintly I will use less pedal to get same affect?

[libbydiesel]

I'm not sure if you are responding to 8v or my comments. 

Less tension on the boost pin will allow it to move with less boost pressure applied.  More pressure keeps it from moving until a higher boost pressure.  I am *not* a fan of having a weak LDA spring or dumping more fuel faster.  That results in excessive smoke when boost starts rising and means either a significant waste of fuel at those smokey times or turning the max fuel down resulting in being under-fueled at other times.  Having a consistent amount of smoke under full pedal throughout the range of rpms and boost pressures and then turning the max fuel down to clear the smoke across the board is the way to go, IMO.   

[bbob203]

I'm not sure if you are responding to 8v or my comments. 

Less tension on the boost pin will allow it to move with less boost pressure applied.  More pressure keeps it from moving until a higher boost pressure.  I am *not* a fan of having a weak LDA spring or dumping more fuel faster.  That results in excessive smoke when boost starts rising and means either a significant waste of fuel at those smokey times or turning the max fuel down resulting in being under-fueled at other times.  Having a consistent amount of smoke under full pedal throughout the range of rpms and boost pressures and then turning the max fuel down to clear the smoke across the board is the way to go, IMO.   

All parties seemed to have equally contributed to my progress here. I think at the stock k14 boost pressure.. where I currently have it set bottomed out I'm achieving what you are suggesting andrew I think I may have to kick my max fuel down a tick to be optimal. Then when I turn up my boost a few lbs ill have to re evaluate the spring tension and turn it back up a bit. This pump was originally setup for a bigger turbo than what I've got now so thats my biggest inclination on the spring tension needing adjustment.. idk or maybe since the k14 spools faster a tad more tension from bottomed out might be better? then maybe my max fuel screw wouldn't need touched at all?  hmmm.  all in all I'm much happier where I'm at now its seemingly as responsive or more than before and seemingly the soot has become light grey smoke.

[theman53]

I think of it like this ^

There are several places to have things set that come out the same. Think of the venn diagram with main fuel screw, LDA screw on top, Pin ramp aggressiveness, and spring tension on the LDA being the circles. Where they meet is the range that you want. You can be off a bit on each one and still be acceptable.
Ex less main fuel, but more LDA screw = same fuel or close to it.