The Official 1HD-T/FT Fuel Pump Mod Tuning Thread (19 Viewers)

[Lumpskie]

Run rich as in higher egts at low rpms?

That's what I would think... but I'm a noob at this stuff. The way I picture it is that, with too soft a spring, very little pressure will move the rod, allowing the rod to administer more fuel earlier, when your RPMs and boost is much below max. Then, when you want the fuel, at higher RPMs and max boost, you'll end up hitting fuel cutoff and not get the fuel you want.

But, I've only played with this stuff for a week or so. So don't take my word to seriously.

Which brings me to a story and question for you guys. I was driving home today and, all of a sudden, the LC started making HUGE power. It pulled like a sports car. And my EGTs were really high. So, I pulled the top off the boost compensator and found that the top nut had come off the diaphragm. As I was reattaching, I tweaked the star wheel a bit and noticed that my previous pin setting wasn't quite at max fuel. So, I maxed the fuel pin rotation/position while I was at it.

Now, I get a little more smoke than I like when I accelerate from a stop. Also, on my long test hill, my EGTs will climb a little higher than I want. Is the right way to adjust fuel back at this point to rotate the rod to a less extreme setting? Or is adjusting the main fuel screw the right thing to do? Also, can anyone confirm what the right boost level is for an old school grunter turbo? I'm running 24psi and... well... is just seems like a lot of boost and power!

Thanks for all the help you guys! (and @chapel gate I hope I helped you a bit!)

 

[SeaJay]

at 24psi you will have to increase the star wheel as much as you can

 

[DancesWithMutts]

What differences did you notice with 15psi over stock?

Well "stock" for me was some Japaneses guys attempt to melt a 1HDT, so it ran really strong and pulled away from a stop light like a petrol, but the EGT's were nuts. So even at 15psi it's still "slower" than "stock" if I am keeping the EGT's in check.

agreed with @IanB
do you have the stock CT26 turbo?

Yes the engine is all stock.

 

[DancesWithMutts]

I decided to take some time and go through my whole tuning process so far, for my own record keeping and hopefully it will contribute to others who are coming down the same path.

First I take delivery of the HDJ from it's previous owner in SD, he bought it from land cruisers direct. The PO told me he hadn't touched the pump settings. Driving home I was shocked at how well the engine performed, I had read that when stock they are pretty slow compared to a 1FZE but this thing felt almost as fast off the line and WAY faster when pulling at highway speeds. I was keeping an eye on the EGT gauge and keeping it below 1000F since it was a post-turbo probe.

My first Mod was to move the EGT probe to the Exhaust manifold, On my first drive I realized that this tune was super weird, my EGTs would climb like crazy when the turbo was spooling, the somewhat stabilize at full boost. Just cruising down a flat road at 50 mph could get the EGTs above 1200. I turned the Fuel screw down almost a half a turn and it helped keep things under control while I waited on my boost controller.

Once I installed my boost controller and started trying to adjust it to 15psi it became clear what was going on. The truck would pull like crazy while spooling, then once the boost got above 10psi it would flatline, my EGTs would stop rising and I had no acceleration. Pulling the fuel rod showed my why.

As you can see (hopefully the pic above worked) the wear mark on the fuel rod shows that this thing was regularly going into over-boost cut-off, even at stock boost levels. My theory is that someone wanted more power and just cranked the main fuel screw up so far that it would keep accelerating even with the fuel rod pushed way down into cut-off. This means the engine was getting the most fuel during spooling, which was causing my erratic and hard to control EGTs.

I adjusted the star-wheel over 2 turns counter-clockwise until I was getting this wear mark at 15psi:

As you can see, the pin is traveling just to the cut-off slope at 15psi but no further. Driving now had much more predictable and linear EGTs, but it would still get hot fast if I was accelerating onto the highway or up a big hill. I wanted to de-tune it until it took several seconds of WOT up a hill before I'd pass 1200 EGTs.

First I put the fuel rod on it's deepest cut and started turning down the main fuel screw until EGTs were safe. This worked but it took all of the bottom end acceleration out of it. Pulling away from a dead stop was almost dangerously slow. I set the screw on the top of the diaphragm to it's most aggressive spot, so the fuel rod starts at a lower position. This didn't seem to make a difference.

I started turning the diaphragm towards a more conservative cut to control top end EGTs and turning the fuel screw up at the same time to increase pre-boost and spooling fuel. This seems to be the right approach. Right now I have good drive-ability and stable EGTs. Unfortunately it's not as fast as it was when I first got it, but the goal here is longevity.

I can very clearly see why people add inter-coolers and big exhausts to these engines. They really make great power when you add fuel, the only limit is EGTs.

 

[Lumpskie]

That's what I'm finding too. EGTs seem to be my limiting factor. I'm still foggy on how much boost is safe for both the engine and my turbo too. I can't seem to find good info on that.

 

[diby 2000]

Consensus seems to be that the stock CT26 is only good for 14psi. You can go further but your reducing its expected lifespan.
Gturbo should be able to tell you what their turbo is safe for.
Same with the engine, If your engine is in good shape, there is no reason 30+ psi is not a safe boost number, everyone has their own limit somewhere.

 

[chapel gate]

at 24psi you will have to increase the star wheel as much as you can

So as long as fuel cut off isnt being reached, which mine isnt, the star wheel can just be cranked down?

In the uk we seem to just crank the star wheel down, turn the plunger to its most aggressive profile, turn the little disc thing to its thickest section and crank the main fuel screw up, obviously with a boost and egt gauge. This finer tuning is interesting and new to me.

 

[SeaJay]

So as long as fuel cut off isnt being reached, which mine isnt, the star wheel can just be cranked down?

In the uk we seem to just crank the star wheel down, turn the plunger to its most aggressive profile, turn the little disc thing to its thickest section and crank the main fuel screw up, obviously with a boost and egt gauge. This finer tuning is interesting and new to me.

no, when you increase the boost you need to increase the star wheel, wind it up

 

[Tapage]

Consensus seems to be that the stock CT26 is only good for 14psi. You can go further but your reducing its expected lifespan.

also you are dealing with hot air out of the performance island of the turbo ( map ) so it's more loose than win ..

 

[chapel gate]

no, when you increase the boost you need to increase the star wheel, wind it up

Hmm, been a good while since ive been in there so cant remember which way its fully cranked!

Will double check when i get a minute.

 

[DancesWithMutts]

So as long as fuel cut off isnt being reached, which mine isnt, the star wheel can just be cranked down?

In the uk we seem to just crank the star wheel down, turn the plunger to its most aggressive profile, turn the little disc thing to its thickest section and crank the main fuel screw up, obviously with a boost and egt gauge. This finer tuning is interesting and new to me.

This is how mine was tuned. The result is that your pump is putting out the most fuel when your turbo is building boost, then it cuts off when you reach a certain boost level, determined by your star-wheel setting.

When you're at max boost, you're engine can handle the most fuel with the lowest EGT's, but with your tune you're not getting max fuel and max boost at the same time.

At least that's how I understand it.

 

[mudgudgeon]

Consensus seems to be that the stock CT26 is only good for 14psi.


Same with the engine, If your engine is in good shape, there is no reason 30+ psi is not a safe boost number, everyone has their own limit somewhere.

The over boost light is switched at 15psi, so you can take it that Toyota considered that safe, and probably with some safety margin.
Any gain from running above 15psi on the stock turbo decreases rapidly anyway.

 

[mudgudgeon]

At least that's how I understand it.

Yep.
From your tuning procedure above, sounds like you have this well figured out.

Good write up on your tuning. When I started tweaking mine about 10years ago, there was next to no tuning info on the net at all. Very much trial and error.

Adding a 3" exhaust will give you some pretty decent gains.
You should get faster spool up, better bottom end and mid-range response, and you should be able to tune a bit more fuel out of it too. Plus they sound beastly

Then intercooler

Then turbo upgrade

 

[vwluv10338]

After reading @DancesWithMutts experience I wonder if my truck has been messed with. Everything seems stock but with a 3" exhaust. My truck pulls great from a stop till about 2500 rpms. Then the power feels like it drops off. It's not a big deal because I typically will run up to that point and then shift which drops my rpms to 1800 where my turbo is still spooled and everything is fine. If I push it though you can feel the dip in power at 2500 but if you keep your foot in it you will get a second surge of power up till redline that almost feels like a second turbo is spooling. I have gauges on order so I guess first step is EGT

 

[diby 2000]

I would recommend an AFR gauge for tuning at least.
I barley look at my EGT any more. Usually only to confirm what I think it will be reading as per the fueling the AFR is showing.
I have never had post turbo egt but everyone says pre-turbo is much faster to respond. Well even that is slow compared to the AFR reading.

 

[vwluv10338]

I would recommend an AFR gauge for tuning at least.
I barley look at my EGT any more. Usually only to confirm what I think it will be reading as per the fueling the AFR is showing.
I have never had post turbo egt but everyone says pre-turbo is much faster to respond. Well even that is slow compared to the AFR reading.

I am definitely going pre-turbo. My understanding was I would be able to tune via EGT. AFR would be nice but you still need EGT because the AFR won't tell you when you will melt a piston correct?

 

[diby 2000]

I am definitely going pre-turbo. My understanding was I would be able to tune via EGT. AFR would be nice but you still need EGT because the AFR won't tell you when you will melt a piston correct?

I can only comment from my experience but when the AFR meter reads 22:1, the pre-turbo EGT will eventually settle at about 700C.
When the AFR reads 21:1 the EGT will rise and settle at about 750C.
With the AFR at 20:1 the EGT will rise and settle to about 800C.

Note this is only at full boost. Before any boost is created I'm running about 17:1 AFR but at those low rpm I have never seen the EGT go over about 500C. During spool I have about 18:1 and still the EGT will rarely go over 500C.
I'm sure this is due partially to the delay in the EGT changing and the gauge responding, and also due to the lack of energy in the exhaust manifold at these times.
I guess my point is I can tune to my desired AFR (which dictates the soot level out the exhaust pipe) where if I was tuning with the EGT I would have no idea what was really happening. But at the same time the AFR reading correlates to the exhaust temp once on boost anyway. So I can (and do) use the AFR reading to ensure the exhaust temp does not go high and i'm not doing damage.

 

[IanB]

After reading @DancesWithMutts experience I wo.nder if my truck has been messed with. Everything seems stock but with a 3" exhaust. My truck pulls great from a stop till about 2500 rpms. Then the power feels like it drops off. It's not a big deal because I typically will run up to that point and then shift which drops my rpms to 1800 where my turbo is still spooled and everything is fine. If I push it though you can feel the dip in power at 2500 but if you keep your foot in it you will get a second surge of power up till redline that almost feels like a second turbo is spooling. I have gauges on order so I guess first step is EGT

Do you have a boost gauge, and are you running stock boost (10psi)? What you're describing sounds to me like the turbo is hitting the wastegate and you're running out of air, power drops off although EGT's will continue to rise as your just dumping in more fuel with no additional air available. I found that by turning the boost up to 15psi the effect was an extended powerband that would continue to pull up to about 3000-3200rpm, not a lot of additional power, but much more useable power if that makes sense. A powerband 5-700rpm wider is a big deal on a low revving engine like these.

 

[vwluv10338]

Do you have a boost gauge, and are you running stock boost (10psi)? What you're describing sounds to me like the turbo is hitting the wastegate and you're running out of air, power drops off although EGT's will continue to rise as your just dumping in more fuel with no additional air available. I found that by turning the boost up to 15psi the effect was an extended powerband that would continue to pull up to about 3000-3200rpm, not a lot of additional power, but much more useable power if that makes sense. A powerband 5-700rpm wider is a big deal on a low revving engine like these.

It's all stock as far as I know unless someone touched the pump. It's stock boost and the overboost light never comes on. I have a boost gauge, manual boost controller, and EGT gauge on the way

 

[mudgudgeon]

are you running stock boost (10psi)?

stock boost should be higher than 10psi.
the FSM describes a test for the turbo charger that should show 10psi. this test is done stationary, revving the engine to a set RPM with no load. this means minimal fuel, and not a lot of drive energy.
I found with mine, when i did this test i got boost around the 10psi mark (can't remember exactly), but in real driving conditions with all else being equal, peak, or max boost would be up around 13-14psi.