The Official 1HD-T/FT Fuel Pump Mod Tuning Thread (6 Viewers)

[IanB]

@Lumpskie Do you have the ECT button, and O/D off buttons in your truck? If no, you've likely got a fully hydraulic A442F ('90-92), no electronics. You would normally only have torque convertor lockup in O/D with this version, but as it's a wholesale automatic unit it could have the upgraded valve body in it, and lock up in 3rd &/or O/D, you should ask Tor if he knows if that's the case. Whatever the case, make sure you get a trans cooler ASAP if they didn't retain the one in the truck.

Adjusting the cable is very easy, just need a 14mm wrench, half turns at a time, adjust, test, adjust, etc. My last truck was a slug when I got it, I figured this out when we stopped in Calgary, so too late to enjoy in the mountains sadly. Really improved how the truck drove, the boost lag previously was brutal, made it dangerous to pull across a lane of traffic. You should be able to downshift with the gas pedal if properly adjusted, and it will hold gears longer as it's all dependent on that cable's adjustment.

 

[Lumpskie]

@IanB

You got it. It's the older full hydraulic A442 and it has the lockout in 3 and 4. The trans cooler looks pretty standard so I don't know if it's OEM or a generic... but at least there is one in there!

If I get time tomorrow, I'm going to read up on adjusting the cable. Hopefully I can get it fine tuned before my commute on Monday! (Especially because my boost controller should arrive Monday!)

 

[Lumpskie]

@IanB Thanks for your suggestion on adjusting the kick down cable. I adjusted that and I can get my rig to shift down much better now! Also, with that, my EGTs dropped 100 degrees on the hill by my house. At this point, my EGTs on the hill near my house are down to about 1000. My Dawes boost controller arrived in the mail as well. I think I'll have time to install it late this week.

Thanks again,

 

[mudgudgeon]

Is your EGT probe before or after the turbo?

 

[Lumpskie]

Is your EGT probe before or after the turbo?

It is just before the turbo on the manifold. Here's a picture. Is this standard?

 

[IanB]

It is just before the turbo on the manifold. Here's a picture. Is this standard?

Yup, that's exactly where you want it!

 

[mudgudgeon]

yup, that's the best spot for it.
Based on that, and your EGTs after you tweaked the auto kick down cable, you probably have quite a bit of room to improve the tune and add some fuel to liven it up a little. See what a bit more boost does, but 1000*F is very safe.

 

[DancesWithMutts]

In anticipation of taking delivery of my '90 HDJ81, I read this entire thread. I learned a great deal about these engines and diesels in general.

My question is this, if my goal is fuel economy, would I tune differently than what is recommended here? I understand that on a petrol engine, a correct tune is generally the most efficient and powerful, but I wanted to know if diesels were the same.

 

[mudgudgeon]

In anticipation of taking delivery of my '90 HDJ81, I read this entire thread. I learned a great deal about these engines and diesels in general.

My question is this, if my goal is fuel economy, would I tune differently than what is recommended here? I understand that on a petrol engine, a correct tune is generally the most efficient and powerful, but I wanted to know if diesels were the same.

if fuel economy is important, the best way to get it is to drive wearing your grandma's slippers and hat, or sell your cruiser


to tune for economy, you need to optimise the efficient combustion of fuel across the whole range so you get the most bang for buck on every ounce of fuel that you use. tuning for power is basically the same deal, except you dial in a bit more fuel to be certain you ALWAYS have enough fuel being delivered to make the most of the additional air being supplied by the turbo.

for economy, I would say you need to go through all the same steps, but your settings will be just a little less aggressive.

Ultimately, economy is determined by your right foot, particularly with a diesel. For a diesel, engine speed and power is determined by how much fuel is delivered regardless of how much air is entering the engine. Diesel always has a wide open intake (not throttle) and draws in full cylinders of air, more when turbo charged.
On a petrol engine, the amount of fuel delivered is determined by how much air is entering the engine. air flow into the engine changes with throttle position, fuel delivery is adjusted to match the air flow.

 

[DancesWithMutts]

if fuel economy is important, the best way to get it is to drive wearing your grandma's slippers and hat, or sell your cruiser


to tune for economy, you need to optimise the efficient combustion of fuel across the whole range so you get the most bang for buck on every ounce of fuel that you use. tuning for power is basically the same deal, except you dial in a bit more fuel to be certain you ALWAYS have enough fuel being delivered to make the most of the additional air being supplied by the turbo.

for economy, I would say you need to go through all the same steps, but your settings will be just a little less aggressive.

Ultimately, economy is determined by your right foot, particularly with a diesel. For a diesel, engine speed and power is determined by how much fuel is delivered regardless of how much air is entering the engine. Diesel always has a wide open intake (not throttle) and draws in full cylinders of air, more when turbo charged.
On a petrol engine, the amount of fuel delivered is determined by how much air is entering the engine. air flow into the engine changes with throttle position, fuel delivery is adjusted to match the air flow.

Thanks for the reply, you pretty much confirmed what I was thinking. My main reason for getting a 1HD-T powered rig is fuel economy believe it or not. My FZJ80 gets 12mpg, even less when loaded down. I read that I can expect 18-22 with a 1HD-T.

 

[mudgudgeon]

yeah, you should definitely do a lot better economy than what an FZ80 will do. is the hdj80 stock?

 

[DancesWithMutts]

yeah, you should definitely do a lot better economy than what an FZ80 will do. is the hdj80 stock?

Yeah, just a lift, tires and bumper. I am thinking about adding an intercooler and a 3rd gear lockup valve body. I am in Colorado and I have lots of mountain passes to pull.

 

[mudgudgeon]

an intercooler will help. Your limitations on power and economy will be the stock exhaust, and also to an extent, the stock turbo.

adding a 3" exhaust to mine made a big difference in how responsive the turbo and engine was over the whole RPM range. A lot better low end response, and more top end power, and better response in general.

Not sure you'd recoup the cost of fitting a 3" exhaust through the improvement in economy, but it makes a big difference in how they drive. I dare say in Colorado, you'd appreciate the difference.

 

[DancesWithMutts]

The rig only has 123,000kms on it, and I plan on having it for a long long time, maybe I will re-coupe the costs. I'll have to get some quotes.

 

[DancesWithMutts]

an intercooler will help. Your limitations on power and economy will be the stock exhaust, and also to an extent, the stock turbo.

adding a 3" exhaust to mine made a big difference in how responsive the turbo and engine was over the whole RPM range. A lot better low end response, and more top end power, and better response in general.

Not sure you'd recoup the cost of fitting a 3" exhaust through the improvement in economy, but it makes a big difference in how they drive. I dare say in Colorado, you'd appreciate the difference.

I'll probably hold off on the turbo for a while, my goal is long term reliability and efficiency, I'm fine with slow.

 

[ForealBoreal]

Thanks for the reply, you pretty much confirmed what I was thinking. My main reason for getting a 1HD-T powered rig is fuel economy believe it or not. My FZJ80 gets 12mpg, even less when loaded down. I read that I can expect 18-22 with a 1HD-T.

How is the truck built. Honestly it's going to be between 16-18mpg.
Especially with bigger tires, a lift and some armour. More s*** you bolt on the worse it gets.
Also if you are driving hilly mountainous spots don't expect the best economy.

 

[DancesWithMutts]

How is the truck built. Honestly it's going to be between 16-18mpg.
Especially with bigger tires, a lift and some armour. More s*** you bolt on the worse it gets.
Also if you are driving hilly mountainous spots don't expect the best economy.

It currently has a OME 3 inch lift, 285's, ARB bumper with factory winch, safari snorkel. It's going to get a 4x4 Labs dual swing bumper, slee sliders, prinsu rack and roof top tent. it's going to be a full expedition build to take me to south america and beyond. Even at 15 MPG i'd be happy, that's still 50% better than a 1FZ-FE powered rig with that much load on it.

I also want the mechanical simplicity of a diesel, my OBDI powered 94 FZJ has been a nightmare to get through emissions testing in Colorado.

EDIT: Hey @ForealBoreal, Have you gotten a bigger scoop ontop of that Ebay intercooler yet? did you see any EGT improvement with the supplied scoop? Are you using the supplied fan?

 

[ForealBoreal]

@DancesWithMutts yes I put an FRP STi Scoop on it.
It did drop them a little and I am sure it will be better when I finally get around to completely sealing it to the hood.

 

[vwluv10338]

Thanks for the reply, you pretty much confirmed what I was thinking. My main reason for getting a 1HD-T powered rig is fuel economy believe it or not. My FZJ80 gets 12mpg, even less when loaded down. I read that I can expect 18-22 with a 1HD-T.

My truck gets around 17-18 mpg on the interstate depending on the speed I drive. I can get around 20mpg if I just drive to and from work on my local highway not exceeding 55mph. This calculation should be close as I try and adjust due to tire size. My truck has a 4" lift and is on 35"s with stock gearing. I would love a set of 3.70s since I like to drive around 72 mph on the highway and even with my tires that spins my engine to around 2600-2700 rpm I believe.

 

[DancesWithMutts]

@DancesWithMutts yes I put an FRP STi Scoop on it.
It did drop them a little and I am sure it will be better when I finally get around to completely sealing it to the hood.

Would you recommend it?