Ideas for improving the 2LTE (2 Viewers)

[advlars]

Hey all,
I just got an 85 pickup with a 2lt (not the 2lte) seems like most of these mods would be valuable to me, and Ive already started a few of them like the EGT install. My question though is if and how I will need to adjust the air/fuel mix when I do things like adding an intercooler or larger exhaust etc. Im assuming your 2lte will adjust the fuel mix on its own but mine wont? Or is the idea here to just get more air in and leave the fuel input alone to keep it cool?

Fwiw this is my first diesel. Been reading a lot but Ive still got a lot to learn

Thanks

 

[raevenzero]

Yours is mechanical, so you have to manually adjust the fuel. There is a bolt on top of the injector pump towards the front. Boat will go up with fuel to an extent because there will be more gases leaving the engine driving the turbine. I personally went with an aftermarket wastegate actuator that I can change Springs on so that I can better control the noisy pressure. Too rich and the engine will run hot and smoke. Too much and you could over boost or create intake heat because the turbo is running too hard. An intercooler increases efficiency by cooling the hot air from the turbo allowing more air to be used at the same pressure. Just make small adjustments while watching the boost and egt Guages.

 

[advlars]

Is that all there is to it? Just righty-richer/ lefty-leaner (or vice versa)? No changing jets/injectors or dealing with 3 different rpm-dependent fuel circuits like my dirtbike carb?

Too much _____ and you could over boost or create intake heat because the turbo is running too hard.

Did you mean too much air? or fuel?

Also, this is a terribly noob question Im sure but I keep seeing references to more air=cooler, More fuel=hotter but this is the total opposite of everything I know from gas engines. Can somebody explain the science on why this is the case with a diesel...

 

[IanB]

Is that all there is to it? Just righty-richer/ lefty-leaner (or vice versa)? No changing jets/injectors or dealing with 3 different rpm-dependent fuel circuits like my dirtbike carb?

Did you mean too much air? or fuel?

Also, this is a terribly noob question Im sure but I keep seeing references to more air=cooler, More fuel=hotter but this is the total opposite of everything I know from gas engines. Can somebody explain the science on why this is the case with a diesel...

I won't get into specifics of how to adjust the injection pump, cause I've never done it, but generally there's an off-boost fuel adjustment, and main fuel adjustment, along with the fuel pin grind which is basically your fuel curve, and a star wheel that adjusts how deep into the pin you are at a given throttle input. This is a very basic understanding, and should not be relied upon for tuning purposes.

I can explain a bit the air=cooler/fuel=hotter bit though. There's no ignition system on a diesel, and no throttle butterfly (except where it's been included to aid shutting down the engine smoothly). So the engine gets all the air it can breathe whenever it wants, and the timing is controlled by when the fuel is injected. As the air is compressed in the cylinder it gets hot, the fuel is injected and ignites due to the heat and pressure. The volume of air is the same no matter what the throttle input, but the fuel is increased with more throttle input, more fuel = more power, more power = more heat.

Then you add boost to the mix, so you're ramming air into the cylinders, leaning out the air/fuel ratio, leading to cooler EGT's (exhaust gas temp). This holds true as long as the turbo is in it's efficiency range, push beyond that and you're just adding more heat to the equation, with diminishing returns. The turbo relies on the energy in the exhaust to spool up, so you could reach the point where your turbo won't make more boost unless you add more fuel to make more waste energy to spin it faster.

In short, the relationship is the reverse of a gas engine, where running lean = running hot, and more fuel = cooler/safer. Hope this isn't too confusing, lol.

 

[gerg]

Diesels don't quench their flame front as it burns relatively slow and won't detonate.

 

[advlars]

there's an off-boost fuel adjustment, and main fuel adjustment, along with the fuel pin grind which is basically your fuel curve, and a star wheel that adjusts how deep into the pin you are at a given throttle input. This is a very basic understanding, and should not be relied upon for tuning purposes.

Ok, so that sounds more complex than just turning a a single screw back and forth... Anybody got a resource specific to the 2lt on how to make these adjustments? Is there a page in the FSM im not seeing?

Diesels don't quench their flame front as it burns relatively slow and won't detonate.

Meaning the fuel is still burning after it leaves the cylinder/ there are flames in the exhaust manifold? Should I be tuning to prevent this? Im not sure I understand what youre getting at.

So in summary, it sounds like I cant run too lean unless I pump in so much air I over-tax the turbo. So to achieve lower egts (and presumably better fuel mileage), would it be safe to put on a larger exhaust and intercooler and leave the fue settingsl alone as long as i monitor my guages for unexpected excess boost/heat? Or will these mods add enough airflow that I will wind up cycling too much air through the turbo and creating too much boost pressure?

Thanks for the info guys. This is great help.

 

[gerg]

In part, gas engines cannot run ultra lean air fuel ratios due to the excessive heat generated and the ultimate detonation that can result. Rich air fuel ratios are used to quench the flame front and prevent the air fuel mix from reaching the critical temp required to auto ignite. The air fuel mix then switches from a burn to more of an explosion where all the fuel burns simultaneously. I'm guessing really high peak cylinder pressures result.

Properly tuned diesels burn and never ever get even close to detonation so ultra lean air fuel mixtures result in a gradual more complete burn on the piston down stroke. Emphasis on burn....slow burn. It actually takes a longer stroke and lower rpm to allow the diesel to burn in satisfactory manner to transfer the energy to mechanical efficiently. Only at high rpms does the diesel leave the cylinder unburnt as then it isn't given sufficient time to burn before it gets ejected out the exhaust valve. Incomplete combustion then results in large amounts of ash. This can also be accomplished with really retarded timing. Or low air fuel ratios where there isnt enough readily available air. Dirt injectors can do it too as the time required to burn through the depth of a large particle to the center is greater than that of a smaller particle based on surface area and mass. Sort of like why babies get cold really easy when they are born. High surface area vs mass. You want your fuel atomized like a cocaine preme, rather than a Roseanne barr style droplet. And yes I have cared for many a cocaine preme in my career.


So turbo boost, like most things in life, is a balance. It takes power to run a turbine and it can create high drive pressures that will choke your engine. Your exhaust stroke drives your turbine, that and the heat in the exhaust. What is the perfect air fuel ratio? I dare say that is a deep subject. Because most of our systems are mechanical we tune for an operating range that is safe for the components both thermally and mechanically. Altitude, temperature, fuel grade, wife driving are all unforeseen variables. I tune my truck so my wife can't destroy it. 1200f max egt WOT. That translates to retarded timing and more boost than it needs. My wife hates shifting so she rarely does. She basically drives around town in 3rd and sort of does this super slow rolling stop in gear at intersections that almost stalls the engine, then she matts it back up to the speed limit. Now you tell me...how the heck do you tune for that?

 

[GTSSportCoupe]

Ok, so that sounds more complex than just turning a a single screw back and forth... Anybody got a resource specific to the 2lt on how to make these adjustments? Is there a page in the FSM im not seeing?

You've got this manual right? http://www.toyota4wd.dk/Teknik/J70/Toyota Motor Manual 2Lt.pdf

Got to page 105 (FU-31) for the start of how to do pump settings. You should read the whole fuel section too to get an idea of the components of your pump.

You should also check out this forum, as there are a lot more guys with your type of 2LT there: Toyota 4WD Surf Owners • Index page Also, they have lots of tech info here: Surf Maintenance

 

[advlars]

You want your fuel atomized like a cocaine preme

Ah!!! Well you explain it in terms of which size child is easier to set on fire it all makes perfect sense! Haha. But seriously that was all great info. I think im starting to get this...

You've got this manual right? http://www.toyota4wd.dk/Teknik/J70/Toyota Motor Manual 2Lt.pdf

Got to page 105 (FU-31) for the start of how to do pump settings. You should read the whole fuel section too to get an idea of the components of your pump.

Ive got that manual but didnt really know where to start, and the manual still doesnt explain much of the concept behind the adjustment.

Im assuming "pre-set load injection volume" is the screw mentioned by raevenzero? Is "pre-set maximum speed" on the next page another fuel circuit that comes on at high-rpm/WOT (like the main jet in a gasser carb) or is that just a physical governor that keeps the throttle from opening any further?

I dont see anything related to the off-boost fuel adjustment or fuel pin grind adjustment that IanB referenced though, unless its called something different? or maybe that doesnt apply to this engine?

 

[IanB]

I dont see anything related to the off-boost fuel adjustment or fuel pin grind adjustment that IanB referenced though, unless its called something different? or maybe that doesnt apply to this engine?

The fuel pin grind is definitely not something you'll find referenced in the FSM, as it's not something a Toyota tech would ever be called upon to mess with. I can't speak to the off-boost fuel adjustment as I've never worked with your specific engine/pump.

 

[kennichi]

Hi everyone, for starters let me say it's a pleasure to be a part of this forum. I just recently bought a lj78 2lte and even though it's not running well for some reason I'm still in love with and I'm committed to bringing it back in top running condition. The car is in Haiti and my main problem is it has not force to go up steep hills I have to either shift it on 2 and if the hills is really peak I have to shift it on L to give the engine more force and still it struggles to up hill. It runs fine on flat ground but I also get this little whining sound I was told its sign that the turbo is going bad. I'm kind of on tight budget so the less I can send for now to resolve this issue is what I'm look forward to doing so look forward to everyone advice

 

[advlars]

Kennichi,
Im afraid your lack of power issue might just be that the 2lte lacks power . Can you give any more details about the symptoms? Are you spitting black smoke etc? How fast are you going and how steep are these hills?

Sounds like you should cruise through all the general maintenance first if youre on a budget. Clean your injectors, air filter etc and make sure your breaks arent dragging.

 

[advlars]

Hey guys,

Im trying to plumb in an intercooler and Im a bit intrigued by one of these: http://www.ebay.com/itm/5-CORE-INTERCOO ... 3R&vxp=mtr
Its an oversize side mount IC for a renualt gt 5 turbo.
Im thinking that I could relocate one of my batteries and mount this in its place with a funny looking hoodscoop in the corner above the headlight. This would eliminate the need for a body lift and would keep the unit as far away from the engine heat as possible. I can get these units with or without an additional fan. the core size is 200mmx200mmx130mm so its super thick/deep

My concern is the air flow capacity though. The renault is a 1.4 liter engine. That being said it looks like they can push about 160 hp, which is roughly twice the power of my pickup. Any thoughts?

 

[advlars]

5" CORE INTERCOOLER&12V 80W ELECTRIC FAN;RENAULT SUPER 5 GT TURBO 1.4L 1985-1991

 

[gerg]

Your link was interesting, but didn't have any intercoolers to look at. Gas engines run extremely rich compared to diesels this require less air to make the same power. This allows them to run a smaller intercooler.

 

[gerg]

Ahh sorry. Your last post did show the cooler you wanted. If you look at the pathing of the air it only really uses half the width of the cooler then does a 180 and comes back around. This gives you a lot of backpressure without signifigant temp difference for the majority of the surface. If you really need that design I'd say go for a much larger core.

 

[GTSSportCoupe]

Hey guys,

Im trying to plumb in an intercooler and Im a bit intrigued by one of these: http://www.ebay.com/itm/5-CORE-INTERCOO ... 3R&vxp=mtr
Its an oversize side mount IC for a renualt gt 5 turbo.
Im thinking that I could relocate one of my batteries and mount this in its place with a funny looking hoodscoop in the corner above the headlight. This would eliminate the need for a body lift and would keep the unit as far away from the engine heat as possible. I can get these units with or without an additional fan. the core size is 200mmx200mmx130mm so its super thick/deep

My concern is the air flow capacity though. The renault is a 1.4 liter engine. That being said it looks like they can push about 160 hp, which is roughly twice the power of my pickup. Any thoughts?

I agree with Gerg. The intercooler you are looking at is specific designed for a small space in a particular car. Not idea by any means.

This is more what you want (more pictures here: How to Install a Intercooler on a '91 Prado EX5 (2L-TE)? )

 

[gerg]

Ok so not to knock your idea too much, cus it's just an idea and Ideas are good and an intercooler is something I'm working on presently myself actually, but a 5 inch core would need a fan that costs more than that whole intercooler package alone. Getting a decient amount if air through a 5 inch core is a demanding task.

 

[advlars]

Fair points all around. Thats why Im here asking for input! Back to the drawing board i guess....

Im not sure about the FMIC though. Ive got a bunch of AC bs in the way and I think Ive got a lot less room to plumb things under the hood in my pickup than you might have in your cruisers.

Think a barrel-style air water would be worth a damn? Its about the only thing that looks easy to install...

 

[Touiederosas]

Hi Nick!

As promised, I would stop bugging you through private messages. Now here I am! Haha. But, as you know, I truly appreciate the effort as I do see you and most of the guys here as celebrities in the 78 community!

Okay so to give a background of what I have done so far with my rig:

1.) EGR block off plates
2.) removed both butterfly plates
3.) 2.5 pipe with Borla exhaust
4.) Bumped up the boost to 12.5psi
5.) installed a snorkel
6.) turned spill valve about 1/3 of a turn
7.) installed devils own water/meth injection
8.) trying a new computer box(will explain this in my problem below)
9.) all the usual maintenance items like filters etc

NOTE: my 78 is a Japan export and I live in the Philippines so I do not know how good the wiring is since it is converted to LHD.

PROBLEM:
Any power coming from the rev range of 2000rpm onwards the power is spectacular. More than I need since I do not tow anything at all. It puts a smile on my face that I am able to ride on an incline at 60-70kph coming from a tiny bit of momentum.

My last challenge is, and its been going on for a year is the response from 800rpm(idle) up to 1900rpm, it sometimes is very slow to pick up. Especially on an incline, when i stop in the middle and try to drive again it kind of stalls on D. This is where the computer box from a friend came in - now it has greatly improved(power is more consistent in the low range) but still times where i lose power to stalling on an incline say I start from a complete stop.

Solutions I have picked up from here and he Surf group:
1.) change the spill valve to brand new(note that I do not know if this makes sense)
2.) have the whole car rewired(wont do this if we can trace the possible problem)
3.) check spray pattern of injectors???
4.) check the wire on top of the Injection pump(some guys say its so sensitive or may not be giving enough voltage - 12v)

Thanks so much Nick! Hope I didnt bomb your thread with a long message.

Regards,
Touie