The Official 1HD-T/FT Fuel Pump Mod Tuning Thread

[DancesWithMutts]

First
Is your auto trans good?
What turbo do you have?
What size tyres? What gearing in diffs?

1HD-T can be prone to stalling on steep inclines.
They also lack a bit of torque until turbo is boosting.
That said, with a high load and full throttle, the turbo should spool up quick once you get it making some boost.
Stock turbo, should give you strong torque from 1600ish, definitely by 1800. gturbo and others will be strong at lower rpm.
More off idle fuel should help, also maybe less aneroid spring preload so aneroid allows more fuel at lower boost.

Second
Turn off the A/C, if the idle up is not functioning, turn the A/C off, if it helps, you know need to sort the idle up, or leave AC off.
If you have the same issue with AC off, then changing governor spring might be needed.

Third
Buy a prius


But seriously, a diesel, they sink.
Adding off idle fuel will make it worse, but might help with point 1
reducing idle fuel will possibly make point 1 worse

1. Trans feels great, only 80K miles on the whole truck

2. stock

3. 285's on 4.10's

I have a good preload setting, using the whole flat spot right up to the over-boost ramp. Any softer and I'll be in cut-off. I am thinking I'll turn up the main fuel screw then if necessary spin my aneroid to keep top end EGT's safe. I really need to get my exhaust done, I feel like that might help me spool a little faster.

I was troubleshooting my dual battery wiring and witnessed the up-idle actuator moving, but it reaches the end of it's range of motion before contacting the throttle arm, should be a easy fix I just haven't had the time to mess with it.

 

[DancesWithMutts]

My truck with the stock turbo would do the same thing. I can't remember a time where I Struggled in low range though.
Where you in low range?
Alternatively, as you say you can let it stall up until the turbo comes on, I have done this before out of laziness. It works, but I would not recommend doing it often.

I was in low. Also at high altitude which might actually have a big effect on how it runs when out of boost.

 

[tweeek]

I'm a manual, so I can't comment about the auto, but if you literally are unable to apply enough power to spin the wheels or climb an incline, regardless of how steep, something is not right. Climbing in 1st gear in 4lo should be pretty effortless, regardless of how steep. 3.1 lo gears will help, but IMO there is something else going on (or the auto is really that much worse?)

Edit: I'll also add I've wheeled mine at 7000' and never lacked power like you describe. This was before I was intercooled, with supra wheel on stock ct26, with 315s, so not much different then your situation.

 

[DancesWithMutts]

I'm a manual, so I can't comment about the auto, but if you literally are unable to apply enough power to spin the wheels or climb an incline, regardless of how steep, something is not right. Climbing in 1st gear in 4lo should be pretty effortless, regardless of how steep. 3.1 lo gears will help, but IMO there is something else going on (or the auto is really that much worse?)

Edit: I'll also add I've wheeled mine at 7000' and never lacked power like you describe. This was before I was intercooled, with supra wheel on stock ct26, with 315s, so not much different then your situation.

It'd be hard to replicate the situation with a manual. If I'd had a third pedal I would have been up and over no problem. But I was at a dead stop and couldn't get the rpms to spool the turbo.

I had to detune my truck when I got it, the PO had tinkered with the pump and it was running waaaaay hot. I have it running nice and safe now and it still has plenty of highway power, but it's a absolute dog off the line, so maybe I need to revisit that.

 

[mudgudgeon]

IMO, 3" exhaust is the number 1 requirement if you want to increase performance.
The stock exhaust is ridiculously restrictive, there's loads of room for improvement.
All else kept equal, with 3" exhaust you'll see quicker spool up, better low end throttle response, better midrange torque, a bit more top end, lower EGTs, a tougher exhaust note, more hair on your chest, improved sex life, more bubbles in your beer, . . .


Tuning by seat of your pants is trial and error, and there's more than one way to skin a cat. It's a matter of fiddling, test, fiddle, test

 

[tweeek]

It'd be hard to replicate the situation with a manual. If I'd had a third pedal I would have been up and over no problem. But I was at a dead stop and couldn't get the rpms to spool the turbo.

I had to detune my truck when I got it, the PO had tinkered with the pump and it was running waaaaay hot. I have it running nice and safe now and it still has plenty of highway power, but it's a absolute dog off the line, so maybe I need to revisit that.

Yes I understand there is a big difference. I guess I should add, in 4lo and 1st gear, my turbo really barely spools. The gearing is low enough that there is very little load to spool the turbo, but you should still have plenty of power without it if you are crawling and have good traction.

 

[mudgudgeon]

An auto should climb the same obstacle with greater ease than a manual.

Yes I understand there is a big difference. I guess I should add, in 4lo and 1st gear, my turbo really barely spools. The gearing is low enough that there is very little load to spool the turbo, but you should still have plenty of power without it if you are crawling and have good traction.

I found that with 35"s, manual, and 4.11 gearing there was definitely times in steep stuff it lacked torque before the turbo spools. I could mitigate this a little by revving the engine up so the turbo was spooled, and additional fuel was available

 

[IanB]

I found I could climb obstacles with ease with my auto, low range, 1st gear, 33's, no need to get into boost, crawling is all done below 1600rpm anyways. If your auto isn't putting power to the ground in this situation, I'd be looking into why. It may just be that you need to turn up the off-boost cam adjustment on your IP, or it may be something related to the auto.

 

[Tapage]

they are pretty powerfull even in stock form ..



not my video but you get the idea right ..

 

[mudgudgeon]

they are pretty powerfull even in stock form ..



not my video but you get the idea right ..

The times I felt there was a lack of torque was in steeper stuff than that, but also dealing with rock steps at the same time.
Probably also thinking about a scenario where starting from a standstill in steep stuff.
My 1HZ has more bottom end torque, even with higher gearing.

My HDJ81, LO range, 1st gear, H151, 4.11 gears, 35s, triple locked. 4" dump, 3" exhaust, stock turbo running 18psi, no intercooler.

Probably around 1500rpm before punching it at the top.
Plenty of boost on tap
(Steeper than the video shows)

 

[mudgudgeon]

crawling is all done below 1600rpm

Yeah, probably true

 

[DancesWithMutts]

I was thinking this over today, the fact that it is having a hard time building revs should be an indicator that the trans is functioning well, right? it's effectively sending torque to the axles, which just happen to be locked up.

I should add that this was a VERY steep obstacle, I ran the rest of the trail which was a long climb over several rocks, ruts and tree roots without issue.

 

[DancesWithMutts]

they are pretty powerfull even in stock form ..



not my video but you get the idea right ..

That guy obviously had a manual, and he revved it up pretty good before dumping the clutch.

I think a good way to replicate this issue would be to have the truck on the street in 4hi, put both front tires against the curb and try to climb in from a dead stop. I bet the truck struggles.

 

[dare]

Yes there is something different in the FT pump compared to the T pumps. Pulls harder from 2400 to 3600 rpm. Dont know yet what is causing this. Camplate has higher lift also, 3.2mm compared to 2.8

Just to complete my table, does anyone know how much lift a 1HZ camplate has?

 

[remy]

I think 2.8 as well, but dont know for sure. Havent found a lower camplate than 2.5 on my journey for camplates. Have to pull a 1hz this weekend so i can measure really easy behind the acsd cover.
Later 1hz's have 11mm plunger.

 

[vwluv10338]

Ok, trying not to derail the turbo thread with tuning my truck. I was able to get the fuel rod out today and take a look. You can see where it pin had been riding for the last 25 years and it seems to be inbetween the most and least aggressive ramps. I'm not going to grind on it now because I don't have an intercooler and with some travel coming up soon I can't risk having my truck down waiting on parts or something. Moving the cam on top made a big difference in drivability. It doesn't appear that the pin used much travel. Thoughts on how to make it better? Turn to more aggressive ramp and add clicks to the star wheel? I'm going to paint it when it goes back in too and see how much boost cut is hitting.

 

[DancesWithMutts]

Ok, trying not to derail the turbo thread with tuning my truck. I was able to get the fuel rod out today and take a look. You can see where it pin had been riding for the last 25 years and it seems to be inbetween the most and least aggressive ramps. I'm not going to grind on it now because I don't have an intercooler and with some travel coming up soon I can't risk having my truck down waiting on parts or something. Moving the cam on top made a big difference in drivability. It doesn't appear that the pin used much travel. Thoughts on how to make it better? Turn to more aggressive ramp and add clicks to the star wheel? I'm going to paint it when it goes back in too and see how much boost cut is hitting.

What is the rest of your build?

 

[IanB]

@vwluv10338 It's tricky to tell from the pic, but the wear mark from the follower appears to start about 1/3 way down the grind, and ends short of fuel cut. Stock boost is 10psi, what are you running now? The extra boost will push the pin deeper into the pump body, and you may get into the fuel cut, you'll have to do the paint pen test to be sure, and "recalibrate" the boost compensator for the new boost level by adjusting the star wheel. From there you can rotate the pin towards the aggressive profile and see how it goes.

If you have an intercooler in your plans, I'd personally hold off on adding fuel via the main fuel screw until its in place.

If you could share the details of your setup (boost level, etc) that would be helpful, I can't remember the details from other threads.

 

[vwluv10338]

For some reason my phone keeps crashing when I try to reply. My truck has a 3" exhaust and an MMP turbo. I had said set the wastegate for 18 psi but after adding a bit of fuel it seems like it's set at 20. Luke said my turbos best range was 18-24psi. For some reason my exhaust did not include a downpipe. I have a 3" downpipe and intercooler on their way. I just wanted to maximize my current setup because on 100% stock fuel the turbo was laggy. Now with the boost comp cam set to max down its pretty great. I ran the paint test and I'm definitely hitting fuel cut. The think is my EGTs will continue to rise and can't really go any higher. If I can use the star wheel to keep it out of fuel cut then maybe turn down the main fuel as long as I don't loose my off the line acceleration. Even without and intercooler I would have thought I would be able to add more fuel for the turbo. If I can't make any more adjustments until further mode are made I'm not sad as it drives pretty well right now. I turned it to a more aggressive ramp and took a quick drive and it actually seemed slightly laggier and with more smoke so that doesn't seem to help any. Obviously still hitting boost cut.

 

[IanB]

I'd start playing with the star wheel to tighten up the spring and keep the follower out of fuel cut at your target boost level, this will serve to reduce fueling at lower boost levels, and may even help with the high EGT's as you'll be adding fuel more slowly than your current tune, you'll have to report back with your results.

Once the pin travel is calibrated to your new target boost level, you'll essentially have to start your "tuning" from there (ramp angle, smoke screw, etc), if you're seeing high EGT's now then I'd leave the main fuel screw alone unless you find it needs to be turned down some to bring EGT's into line.

Also, you need new tires, lol.