13B-T Fuel Adjustment - Power Increase; ANSWERED! (1 Viewer)

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danhr

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I have seen countless posts asking how to adjust fuel. I am going to answer all of those in this one thread

I will not be going into details. I will leave that for someone else to fill in the details by follow up.

Just to get conversation started; increasing the fuel and boost will dramatically increase performance. This also means higher EGTs and thus lowering engine life. Increasing the fuel and boost can cause engine breakdown so do it at your own risk. And I am not responsible for any results be good or bad.

There are a total of four fuel increase points.

a) Boost Compensator
b) Max Fuel Screw
c) Guide Bushing
d) Full Load stopper

To increase boost you need to mess around with WasteGate Actuator.

I do not know the functions/working and adjustments of (c) and (d). I will be thankful to who ever explain these.


Now see the picture below which shows the location of boost compensator. This is a RHD vehicle. I have removed turbo intake pipe and one battery. You will need to remove this battery to get easy access to fuel adjustment screw. You do not need to remove the turbo air pipe; I did that since air/oil was leaking from the joint. Later I made a gasket and used silicon to seal it off.

011.jpg
 
Boost Compensator

This second picture is a more close up. I am using the picture ‘close-up’ tactic since Fuel Adjustment Screw is located in a dark spot and a single picture will not help inexperienced people to locate this Max Fuel Screw.

(a) Is the boost compensator adjustment screw. To adjust you will have to undo this cap-bolt. Underneath you will find an all-thread (a rod with threads all over) and a lock nut holding this ‘all-thread’ to its position. This all-thread had a tooth like head and you need a plain screw driver to do any adjustments. You will need to loosen up this lock nut then you turn the all thread towards the engine for increasing fuel. Do it the other way and you decrease the fuel. Actually what happens here is that when you turn it towards the engine, more fuel is delivered under lower boost. Remember boost compensator increases fuel only under positive boost pressure. Thus this tweak only improves performance under boost pressure i.e. when the turbo kicks in i.e. above 2000rpm.
022.jpg
 
Max Fuel Screw area

We are getting closer to the Max Fuel Screw Area. The Circle shows the area. See the next picture.
033.jpg
 
Max Fuel Screw


Finally, the Max Fuel Adjustment Screw. The adjustment of this is similar to that of the boost compensator. You remove the cap-bolt. You will find ‘all-thread’ underneath. You can also see the lock-nut in place (the nut with a hole, just after the cap-bolt) in the picture. Loosen this nut and turn the all-thread towards the engine for increasing fuel and to reduce do the opposite. Again, you need a plain screw driver to turn the all-thread in any direction you want.
044.jpg
 
Wastegate Actuator

After you increase fuel you need to increase the boost to see any performance gain. I will not go into details since there is already too much on the working and tweaking/adjustment of wastegate actuator.

Happy wheeling!:steer:




tags:
How to increase fuel?
13B-T Fuel Increase
Boost Compensator
Fuel Adjustment
How to decrease fuel?
Max Fuel Screw
Max Fuel Adjustment
Maximum Injection Volume
Acutator.jpg
 
Were can I get to see where all the vacuum piping goes ? Had the engine overhauled, but the guys didn't connect all the vacuum hoses right. It is on the intake/dsl pump side.
 
The "Guide Bushing" should be a wheel that you can click up or down (once you remove that hex bolt). Clicking it up, will spin a threaded wheel clockwise, toward front of engine, reducing the spring tension beneath the boost-compensation diaphragm. This will effectively allow more fuel per boost; in other words, as you gain boost you will get fuel sooner, thus raising boost faster. This is a great adjustment for power vs. smoke. Clicking it down, will move the wheel closer to the diaphragm, in effect tightening the spring under the diaphragm, thus requiring more boost to move the diaphragm (and therefore reducing power, smoke, etc.).

The "boost compensator adjustment" is often called a "smoke screw" on other pumps. This adjustment is changing the non-boost level of the boost compensator; in other words, the amount of fuel the engine get's before the boost starts to push on the diaphragm. It's setting the unboosted diaphragm depth.

(ps: diaphragm is hard to spell. I don't like that word.)
 
Great post.

The fuel stop lever shuts off fuel delivery by pushing the lever forward (to the front of the engine).

Holding it in the fuel off position allows rotation of the engine and no fuel delivery. Good for spinning the engine to get oil pressure before firing (after turbo work, etc), the compression check process, and any other time you want to spin the engine over and control fuel delivery.

The fuel stop lever can be used as emergency shut down it safe to do so.
 
Anyone else have some results they would like to share from their tuning?

So far I have only played with the max fuel screw, I increased it by just over 1.5 turns. Car has a 3'' exhaust with a single muffler at the rear, water to air intercooler and max boost spikes to 18.5psi, normally sees 15/16psi though.

Results: Car accelerates MUCH better and has significantly more torque. EGT's have not risen that much. Accelerating full throttle to 60mph reaching 4th gear EGTs raise to 640c pre turbo. While working the car hard offroad and hard onroad up some long steep hills max was 700c pre turbo briefly.

Boost wise I am getting 10psi at ~1900rpm, 15psi at 2400rpm, 16psi 3000rpm. The only times it goes higher than that is at higher engine speeds under high load (ie over taking at 75mph in 4th gear)

I want to play with the fueling more because I notice the car has a significant peak in the power/torque delivery at ~2500rpm to 3000rpm. When accelerating through 2nd gear you can feel the motor pull much harder from 2500 to 3000, its is present in the taller gears to, though to a lesser degree. I am hoping with some better tuning, possibly of the guide bushing I can fatten up the lower torque of the engine.

I am also looking at changing the turbo in the future, I have a small garrett T25 sitting here.
 
One thing about to think about... and I'm not 100% sure, but from what I understand the fuel compensator increases fuel... until it bottoms out, then it actually decreases fuel just a bit. You'll see your boost spike under load, then boost (and fuel) backs itself off a little. Interesting, and probably saves the motor from stressing itself... but sort of annoying too.
 
Interesting thanks. Where would I find more info on how the fuel pump works? like how fuel is metered under different boost/throttle conditions and how the ramp rates and max fuel adjustments effect this?

Where is the idle speed adjustment on this pump too?
 
Got it sorted, mad up a tool to do the adjustment. Was hard to know how many clicks I adjusted it. Has definitely made a difference, more torque at lower rpm, boost does not really rise much quicker though.

From gifu "One thing about to think about... and I'm not 100% sure, but from what I understand the fuel compensator increases fuel... until it bottoms out, then it actually decreases fuel just a bit. You'll see your boost spike under load, then boost (and fuel) backs itself off a little. Interesting, and probably saves the motor from stressing itself... but sort of annoying too."

I have been finding if I hold the throttle pedal just under maximum, say 95% the car seems to pull better than holding it flat.
 
guide bushing adjustment

thank you very much to all the people that have posted all of my questions , and answered them, the last post on fuel, boost compensator, fuel stop , ect , and photos of 13bt where to find all the components to adjust, great post :bounce: :cheers: thanks to hulsty & danhr , enjoy reading all the forums, bill benny
 
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