Diesel newbie thinks 12H-T is underpowered - help needed

[TLink FJ60]

After driving a stock FJ60 for 18 years, I bought a JDM HJ61 with a 12H-T. It has low miles (108k) and is super clean, body, interior, and under the hood. BUT, I am disappointed with the power. Based on everything I have read from others, I don't think it is running like it should.

My FJ60 is quicker and faster than the HJ61 in the entire range 0 to 70mpg. In fact, I can only get the HJ61 to go over 65mph on flat or downhill. Both vehicles have H55F transmission. I'm running 31" tires on both. If anything, the HJ61 might have lower gears although I don't know for sure. (4.10 vs 3.70 maybe). I can hardly climb the hill on my street in 3rd gear at 2200 rpms - I have to slow down and drop to 2nd.

The 12H-T in my HJ61 starts in a nano-second when I turn the key. It runs smooth and sounds great. The green turbo light is on almost all the time, except when my foot is completely off the pedal - that doesn't seem right. It almost feels to me like a diesel without a turbo.

First. Help me determine if my expectations are just off. Should it feel a lot more powerful? Should I hear the whining of a turbo (I don't). What should the behavior of the turbo indicator lights be? What should the power band feel like? Should I expect to pull out in modern traffic without slowing down traffic?

Second. Where should I start in diagnosing the health of my engine?

Note. I've started doing some reading and learning about the engine and turbo - still a long ways to go. One thing I noticed right away...I can not manually move the wastegate actuator rod (with engine off). Should I be able to sense any movement in the lever? It seems frozen - but I haven't tried real hard yet.

 

[niffa]

You should not be able to move the wastegate actuator. Well i cant on mine. Maybe your spring is shot. Quick test, wire or clamp it shut. Take it for a drive and see how u go. Just dont go crazy if u suddenly feel a gain in power. U may detonate your turbo. everywhere iv read these stock ct26's dont enjoy over 16psi for extended periods. Let us know how u go

 

[jzilla]

Do you have a boost gauge? Maybe see if you are losing your boost through a loose hose connection somewhere...

 

[VX 12HT]

It's hard to tell unless you drive another one a quick way is to also get a boost gauge as suggested. Now the other thing the legend never lives up to expectation the 12ht is a fantastic engine but it's not a power house as sometimes it is often referred too, performance is adequate compared to modern standards. Remember it's still only 100kw at the fly with 315 mn of torque pushing a 2 ton truck. Now unless something is just not right with your motor whether it be turbo or fuelling mine really came alive when I got a manual boost controller and upped it to 12 psi.

In order to keep up with any modern diesel you really need something like the gturbo (next on my list) or turbo mods intercooling and such. The gturbo brings you up to just off 500nm of torque which would be awesome at lower revs to.

So yeah check the basics make sure sure all is okay and then you may need to modify to bring her alive....

Mark

 

[Dougal]

Gauges first. Boost and EGT. Fit those and come back to us with the readings.

There are options to increase power, but first you need to know if it's running as it should.

 

[TLink FJ60]

Great. Thanks for the responses. I will install gauges. Will I need to tap a new hole for both? Where is the best spot to tap for the EGT? If anyone has a pic of where your EGT and Boost lines attach, that'd be fantastic.

 

[Gun Runner 5]

This setup is on my 2H (a poor mans 12H-T) but the concept should be the same. Pyrometer (EGT) is tapped prior to the turbo.

 

[Gun Runner 5]

The boost gauge is tapped on the Intercooler return line.

 

[roscoFJ73]

Have you changed the fuel filters and air filters? I would do these as a priority. Poor fuel and air flow will strangle the engine.
I would do this before adding boost gauges as it will give you poor readings if it cant breathe properly.

Do the controls on the pump have the lead wire seals attached? These are attached when qualified people have finished adjusting the fuel pump. If they have been removed it usually indicates that someone else has had a play with it.

My 12HT 5 speed could get to 80kph pretty fast by diesel standards(of the era) You take off in 2nd gear,into 3rd about 2500rpms and you should be moving along nicely. They taper off at about 90kph.
You should be able to take on hills in 3rd/4th effortlessly.
Mine was an Australian model, I have driven 2 JDM HJ61 and they sounded a bit like yours , but they were autos. I dont recall any of them making much turbo whine
From memory ,the carbed 3F I had in my FJ73 probably had a better top end performance than the 12HT but I never drove them back to back and the FJ73 was 150kgs lighter.

Does it make any smoke under load? You should get a puff of black smoke when you start it and another under hard accelleration ,but not continuously.

 

[roscoFJ73]

Another thing ,the JDM imports have along history of odometers being altered. ,it could have double or triple the shown distance. I would also get the cracking pressure on the injectors tested if possible.

And if your fuel filter is particualry grubby,you may have an algae infestation blocking the fuel pick up.

 

[TLink FJ60]

Okay, so it sounds like my expectation for the top end power may be too high, but in the mid range I just don't think I'm there. I definitely struggle on hills in 3rd and 4th gears. Takes forever to get to cruising speed.

I get a puff of smoke on start, but I have not seen any after that even under load - though it might be harder to notice when I'm moving down the road. I'll look a little closer next time.

Yes, I do have plans to replace filters, but have not. Actually the air intake filter looks new. The body of the fuel filter looks new, but who knows. I am always skeptical of the odometer readings, but I will say, this vehicle looks so clean. The body is straight. The interior is really clean. The engine compartment is neat and clean. But there is no way to know.

The fuel pick-up...that is in the tank? Even if the filter looks clean, there could still be algae in the pickup from before the filter was last changed. Is it difficult to get too it?

Okay, like I said, I'm new to diesels - what is "cracking pressure" for the injectors, and if I have it tested what should it be? Will this require a tool or fitting unique to a 12H-T, or should any diesel tech (I'm in the US) be able to do this?

So...
- Air filter
- Fuel Filter
- lead wire seals on fuel pump
- test injector "cracking" pressure
- Boost pressure gauge
- EGT pressure gauge

 

[VX 12HT]

Yeh get your basics checked first mine is a 5 speed like rosco take off in second and she will take off quite nicely mine is low kms only 148,000 when I got mine. I had the basics checked out when I bought mine and was all good but I knew the guy who actually went to Japan and picked his out with only 80,000 kms on the clock. And yeh won't rev like a petrol but there is great performance potential with good fuel economy within the beast....

 

[ozwallaby]

4- Air filter
3- Fuel Filter
5- lead wire seals on fuel pump
6- test injector "cracking" pressure
1- Boost pressure gauge
2- EGT

Try them in this order..... EGT is exhaust gas temp.... it measures the temperature(not pressure) of the exhaust, which lets you know how hot (lots of fuel) or cold (less fuel) your motor is set... simply get the figures and publish here so the collective brain can have a go at what may be wrong or not....

 

[ozcrusier]

Don't forget the water filter halfway along the chassis they block up with crude and are know to give drama to new diesel owners.

 

[VX 12HT]

My jdm import does not have this......

Don't forget the water filter halfway along the chassis they block up with crude and are know to give drama to new diesel owners.

 

[sami]

hi
is the motor 2h-t
or 12ht
to me it looks like a 2h

 

[ozwallaby]

hi
is the motor 2h-t
or 12ht
to me it looks like a 2h

OP hasn't posted fotos here as far as I can tell......... maybe I'm wrong.... what fotos sami?

 

[roscoFJ73]

The fuel pick-up...that is in the tank? Even if the filter looks clean, there could still be algae in the pickup from before the filter was last changed. Is it difficult to get too it?

The filter is inside the metal canister. The fuel pick up is in the tank. Sometimes condensations gets into a tank and water will live in.
An easy way would be to let the fuel level get down and drain the tank through the drainhole underneath the tank.

Okay, like I said, I'm new to diesels - what is "cracking pressure" for the injectors, and if I have it tested what should it be? Will this require a tool or fitting unique to a 12H-T, or should any diesel tech (I'm in the US) be able to do this?

So...
- Air filter
- Fuel Filter
- lead wire seals on fuel pump
- test injector "cracking" pressure
- Boost pressure gauge
- EGT pressure gauge[/QUOTE]

Cracking pressure is when the pump builds enough pressure with a charge of diesel to overcome the resistance from the spring in the injector. As they get old,the spring softens and allows the injector to open earlier and you dont get maximum atomisation.
12HT injectors are a little tricky as they are 2 stage I think. This means they open briefly ,spray a small shot of diesel in ,close and then open again and release the remainder of the charge.
You get them out like a spark plug and you dont allow your fingertips to touch the end(especially after a rebuild)
You need good spanners and a torque wrench
How ever this should be looked at after the easy stuff.

If the lead wire seals are missing,its not necessarily bad , its just that someone has touched the adjustment screws.

 

[roscoFJ73]

hi
is the motor 2h-t
or 12ht
to me it looks like a 2h

You are looking at the HJ75 pics of someone else's vehicle. The owner has stated it is a JDM HJ61. They did have JDM HJ60 but I dont think many were exported

 

[Dieseler]

it says 89 hj61 12ht so I would guess he in fact has a 12ht and not the 2H.
12ht should have good eccelleration 2nd to 4th when the pedal hits the medal ( I have 35s and hit freeway speeds lickity split) .
The 12ht will climbs hills in 3rd and fourth with no effort mine will hold 80 kmh or 50 mph in 4th on the steep long climbs.
You have some sort of starvation problem whether its fuel or air (turbo) the turbo on the 12HT does not whine persay it just grovels.