IP adjustment questions
 

ok, im about to do this..... I'm taking the GTI out of the garage after being neglected for about 4 months only driven once for no reason other than I love driving this Mercedes....

After installing pyrometer, I'm going to adjust the IP... i'v read some threads about adjustment but some things I find confusing...

1. What gains would I expect if I just adjust the full load screw? Would it be in the whole power band? I don't want to trade low end for high end, or vice versa...

2. Does taking off the rack limiter yield more gains from just the full load screw??

3. What does adjusting the torque capsule do?

4. One more... .Does adjusting the high idle screw increase any fuel delivery at high rpm? I don't really need the car to rev any higher but some more power in the upper rpm band would be greatly welcomed. :D

It might be helpful to know what type of IP you have. MW or M.

On most Diesels that Full Load Screw is set to protect the Engine from going above a certain RPMs so that the Engine does not self destruct. If it functions correctly is the Governor will nearly shutoff the Fuel so that the Engine cannot overspeed (on other Engines it is called the High Idle Speed).
I believe the RPM limit on my Engine is 5100 RPM.

On the other Engines and Fuel Injection Pumps I have worked on the Governor is set to star cutting back the fuel at 200 RPM below the Max RPM. By the time you get to the Max RPM you IP output should be very little.

So by messing with it you would have to set it so that that fuel will not start cutting off until a even higher RPM. Meaning passed the safe RPMs/"Red Line".

Since if set properly it only operates at the near Max RPM range; setting it to a higher setting would only increase the power within the 200 rpm range at the Max RPMs. It should not have any effect on the Engines Operation at lower RPMs.

ok that makes sense, so what does removing the rack limiter do then? and the torque capsul? i want to get the most out of my ip but i would like to not mess up my powerband, i just want more but with the same powerband..... more high end power and more low end torque

I believe that you have to bore out your elements then....

well lets say i want to get as much as i can out of my ip without goin nuts.... just twisting and turning some stuff and removing the rack limiter,


btw how much faster does the car feel when all this is done?

I think you are confusing high idle with full load. Full load controls max rack travel by controlling the rack limiter.

I removed my rack limiter on my 617 and it made a huge difference. All pumps are gunna be a little different so your results might not be exactly the same as mine. I'd say go for it though. I also messed with my torque capsule. I wouldn't recommend this unless you have a back up pump in stock form to replace if something goes wrong. I adjusted mine to the point where it belched black smoke at idle. When I tried to reverse my doings, it made it not want to idle smoothly. It kept loping. I put in a stock pump I had for a spare, removed the alda, removed the rack limiter, and timed it to 28* with the drip method and haven't looked back since. She can belch black smoke right now right before it builds 18psi worth of boost and chirp the tires at each shift.

If you PM me your E-Mail address I can send you the Bosch training information I have. It is 3 meg so I can not post it. It provides a good overview of how the settings interact with each other, throttle input, and engine speed.

With a basic understanding of the operation of each setting we can then begin a discussion based on consistent and accurate foundation.

Competence should come before confidence.

how much more torque can i expect to get out of these adjustments? i think i heard 50 ftlbs before but i dunno if that is correct

anyone kno the amt of torque this mod can yield?

I went back and read what the OP said. Perhaps I am not used to the terminology full load screw. Some refer to the Throttle Lever Stop on the outside of IPs as the Full Load Stop/full Throttle Stop Screw so I thought that was the same as full load screw.
Also when I looked at the schematic of the IP Governor in the FSM I did not see anything labeled as full load screw.


The high idle is not set under a load.

Below is a generic explination.

When the IP is on the Calibration Stand you have the Throttle Lever at Full Throttle against the Full Throttle Stop Screw.
You increase the test stand RPMs that at about 200 RPMs below the Max Safe RPMs the Engine Manufacturer wants. At that point the Throttle Stop Screw is adjusted so that the fuel quantity coming out of the hard lines starts starts to decrease.

As you continue to raise the RPM the fuel continues to decrease until at that Max Safe RPM there is very little fuel.

When this is happening it is the IP Governor weights are compressing the a spring (the same spring the Throttle lever pushes on) and pulling the Rack Back and decreasing the fuel.


You can do this adjustment on the Vehicle with a Tachometer. Again there is no load on the vehicle (not moving sitting stationary). Your rev the Engine up to that MAX RPM for a brief period of time at which point Governor should be trying to shut it off. If it does not start to shut off properly you adjust the Throttle Stop Screw so it does.

I looked in the FSM Mercedes does not want you to do the adjustment on the vehicle. They want the IP removed and put on the test stand.

for an 84 300D in the FSM, 7.1 Injection System then go to 105 Checking the Maximum Speed At No Load. The speed is listed ad 4900-5200.

On the old Big Rig Engines (1970s) the High Idle Speed was around 2100-2200 RPMS.

Full load screw is inside the IP controls the rack max limit. The screw where the linkage hits is there only to prevent binding internally. The high idle screw, also inside the IP center, up and to the left of the full load controls max rpm.

The torque screw is the biggest pita of them requiring a special slotted tanged socket.

Torque is a function of volumetric efficiently and fuel.

It is my understanding that the cam in the 617.95 is designed to be the most efficient in the 2000 to 3000 RPM range. The stock turbo, IMOP, dose not complement that range, especially off the line.

A VNT type of turbo would allow you to change the torque curve (compared to the stock turbo) by making boost at or just off idle, allowing the engine to produce more bottom end torque with out doing any IP adjustments because the ALDA only cares about boost pressure, not engine speed.

On a separate note;

I sent out the governor info to those who requested it. Is there a way to post it ( it is 3meg) because it is becoming a pain to send it?

Many people already have it. The main problem with it is that it dose not tell you "if you turn this screw, X amount, then you will get X more fuel" It only explains the responsibilities of the individual governors and how they interact with each other, engine speed, and throttle setting.

It also illustrates the individual fueling curves, which should allow one to imagine what they would like their fueling curve to be, and, with the understanding of which governor influences that potion of the fuel curve, one could then have an intelligent discussion regarding the possible adjustments to achieve the desired fueling curve.

I apologize for the delay in sending the file to some. I received a return mail error after trying a mass sending. I resent individually.

im hoping i can do this stuff soon, my gti has been sitting in the garage so long the battery discharged and when i charged it up the freakin alarm started going off and the key fob wont disable it for some reason so apparently i have to look for a damn switch hidden to disable the alarm.... (sighhh) sux.... espically since ill have all weekend to work on my car since i am not going out of town this weekend. sux


anyway, first thing i think im gona do is just turn up the full load (rack limiter) screw and see if i can get some decent gains from that. i just sold one of my money making cars yesterday so i have some money to spend and i really want to find a sprinter or liberty turbo also..