Overcoming 2LTE fuel cut limit

GTSSportCoupe

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OK I'll try to clarify a bit here.

Under 14psi boost, you don't need this bleed valve at all. Or just screw it all the way closed.

Your boost gauge should read out from the intake manifold only. There should be no restriction between the intake manifold and your boost gauge (sensor). You need to T-off your boost gauge (sensor) BEFORE the little filter thing (23265 - in the above Toyota parts picture). The bleed valve I sent you goes AFTER the little filter thing (as I drew with the red circle above).

Say you want to tune for 16psi for now. You need to turn your manual boost controller screw in a couple of turns to keep the waste gate from opening too early. This will take some experimentation, because the computer will cut fuel to try to keep your boost down again (until you get your air bleed valve adjusted right).

Go for a drive and see what happens. If you're hitting fuel cut (check engine light and loss of power), then open up the bleed valve a 1/4 turn and go for a drive again. If you're not hitting fuel cut, then close the bleed valve a 1/4 turn and go for a drive again.

Once you've found the point on your bleed valve just before the CEL comes on, you are very close to the final setting. In the case of the 2LTE I can say that the computer starts pulling fuel even before the CEL comes on. So I had to OPEN my valve another 1/2 turn or so before I started getting peak manifold boost pressure and engine power.

It's going to take a bunch of time driving, and adjusting to get things nailed down. I'd put aside a couple of hours to do the tuning. Find a safe rural road to do this where you won't be bugging people.

You have a couple of variables here to adjust: your manual boost controller and your bleed valve.

Try to get those pictures uploaded so I can help make sure everything is connected right....
 
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Thank you for the detailed explanation! Everything is set up as you described and I have been doing everything like you describe in shooting for a 16 psi boost EXCEPT that I have my boost sensor after the filter and not before. My thinking was to protect the sensor by putting after the filter but perhaps that restriction is not giving me a true measurement of manifold boost. THANK YOU for the clarification- I will switch that around.
 

GTSSportCoupe

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Thank you for the detailed explanation! Everything is set up as you described and I have been doing everything like you describe in shooting for a 16 psi boost EXCEPT that I have my boost sensor after the filter and not before. My thinking was to protect the sensor by putting after the filter but perhaps that restriction is not giving me a true measurement of manifold boost. THANK YOU for the clarification- I will switch that around.
I'd highly recommend moving your boost gauge sensor (for gauge readout in the cab) to before the filter.

For two reasons:

- One: you should know the pressure that's actually going into your engine. It's not critical to know the pressure that you're tricking the ECU boost sensor into seeing.

- Two: the extra vacuum hose to your boost gauge sensor increases the volume of air between the filter and air bleed/ECU boost sensor. The filter restricts the air flow, and the air bleed valve is leaking air. This means you'll get strange lag issues with more air volume (it'll take a while to 'fill' with pressure), and the air bleed setup may never work right. In fact, your boost gauge may never work right either.

Vacuum Hose2_2.jpg
 
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Fueling is a component of creating boost.Your spill valve may be set at a point that the amount of fuel you are able to receive will only create a maximum of 14PSI of boost.
So, to create more boost will require more fuel. However, more fuel will also create more heat. Your goal is to adjust both in conjunction to to find a sweet spot that produces sufficient boost to help offset the additional heat generated by the additional fuel. Those of us intercooled at running max boost pressures that are actually dictated by the amount of fuel the IP will deliver, not the max boost the turbo is capable of producing. My boost controller for instance is bottomed out. I believe Nick's is as well. But, because of the intercooler, we can utilize the additional fuel without creating a heat problem once the pump is turned up.
It's sort of a balancing act, and every injection pump will produce slightly different results.
With all the diesels I have tuned, no 2 are set up exactly the same. They all take a bit of trial and error. I can for instance get a 300TDI Land Rover engine pretty close by ear and feel, but it still requires test runs to wring out all the power it is capable of producing while not getting the EGT's too high on sustained pulls. And, they vary wildly on where that is. I have not tinkered around on that many LandCruiser engines, but that has been my experience on the ones I have seen and really nearly every other diesel that isn't 100% ECU controlled.
 
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Thanks guys! This is going on the back burner for a few days and I will get back with a fresh approach. I need to get some more vacuum line and lay things out better and start fresh.
 
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Fueling is a component of creating boost.Your spill valve may be set at a point that the amount of fuel you are able to receive will only create a maximum of 14PSI of boost.
So, to create more boost will require more fuel. However, more fuel will also create more heat. Your goal is to adjust both in conjunction to to find a sweet spot that produces sufficient boost to help offset the additional heat generated by the additional fuel. Those of us intercooled at running max boost pressures that are actually dictated by the amount of fuel the IP will deliver, not the max boost the turbo is capable of producing. My boost controller for instance is bottomed out. I believe Nick's is as well. But, because of the intercooler, we can utilize the additional fuel without creating a heat problem once the pump is turned up.
It's sort of a balancing act, and every injection pump will produce slightly different results.
With all the diesels I have tuned, no 2 are set up exactly the same. They all take a bit of trial and error. I can for instance get a 300TDI Land Rover engine pretty close by ear and feel, but it still requires test runs to wring out all the power it is capable of producing while not getting the EGT's too high on sustained pulls. And, they vary wildly on where that is. I have not tinkered around on that many LandCruiser engines, but that has been my experience on the ones I have seen and really nearly every other diesel that isn't 100% ECU controlled.
With my recent SV adjustments, this may be my issue...
 
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Finally getting ready to play with this on mine, with this though the line you tap into for the bleed off is the same line I run my boost gauge from. Will this still be sweet if I add the valve t in after the guage? Or should I move the gauge line?
 
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sweet, was just worried if the two T's are 10-15cm apart on the same line the bleed off would would still effect the line pressure and put the gauge off.
 

GTSSportCoupe

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sweet, was just worried if the two T's are 10-15cm apart on the same line the bleed off would would still effect the line pressure and put the gauge off.
As per the pictures I put up earlier in the thread, you want the bleed valve between the filter and map sensor. The filter is a restriction, which allows the bleed valve to successfully bleed off the boost. Without it, there would be a virtually unlimited supply of air from the intake manifold, making it not work properly.

However you still want to know how much boost is actually in your intake manifold going into your engine. It will be a higher figure then what is at the bleed valve (as that is the whole purpose). So connect your boost gauge BEFORE the filter.

The filter I'm talking about is part number 23265 in this drawing:

 
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Sorry if im being punishing on this.. below ive drawn in where mine is currently and will be in relation to the T that you show to add, should i keep the guage T here or move it to the other spot ive drawn before the filter then?

Untitled.png
 

GTSSportCoupe

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Yup, definitely move it as you've indicated in your drawing. You don't need to know the boost you are 'tricking' the ECU to read; rather you need to know the boost going into your motor.
 
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Thanks Nick,

Out of interest do you know if the current location would alter the gauge much post filter (as it stands without the bleed off). Im away from the truck today so cant test it, but my max reading is currently 12psi with the T in that location, would this actually be higher at the manifold and ive been reading the boost wrong till now? im still going to add the bleed off and move this now, but would be interesting if this would have been putting my numbers off the last few months or not.
 
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