1hd-t vs 1hd-ft injector pump

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Yep, that's precisely my symptoms as well. Same for many people I have spoken too.
Mine has stalled on several occasions due to this. It's pretty scary when it happens on a steep hill and you start going backwards because you don't have the traction to keep your self there!
 
So are you idling/crawling up a hill? Just had a read through the forums and saw a few other posts on it. Sounds like an idle damper mod. Never struck it before but I'm interested in looking to see if there's a bulletin on it now.
 
I have experienced the uphill idle drop and downhill idle decrease. Again unfortunately after the aforementioned 'Denso dealer' shop tried to rebuild it twice. Never had it prior. As such, don't assume a rebuild will fix it. Manuel transmission.

It is in the range of ~250rpm and extremely annoying. Can increase under brakes (inertia) too.

I could start the engine from cold and it would idke at preset, and then with the slightest throttle touch would go to 850+ rpm.

The turkeys at the shop backed off the dashpot to the point it was disabled trying to fix it but it had no affect on it. There is a thread on this problem.

It went away after the mod to FT specs.
 
Yeah only affects idle on a hill.

My idle is set at 800rpm and is solid as a rock but drop as i face uphill. if im on the throttle i dont notice it. Only bugs me offroad.

I had no idea of this issue until the pump builder told me about. The FT specs must be what he rebuilds them to.
 
Antony said:
So are you idling/crawling up a hill? Just had a read through the forums and saw a few other posts on it. Sounds like an idle damper mod. Never struck it before but I'm interested in looking to see if there's a bulletin on it now.
Click to expand...
With the auto I'm never idling up a hill as you will be slipping backwards through the torque converter. It happens when I remove my foot from the throttle (engine should go back to idle) when pointing up hill for whatever reason. The steeper the hill, the less rpm the engine will idle to the point it will stall.
I'm sure there was a thread on here that solved the issue, I just don't have the time to search for it now.
 
I have asked a few pump technicians about the solution that was found in that thread and to them it still didn't make sense.
 
I don't think it makes sense to many, hence why the problem is rarely resolved. Even with a pump rebuild.
When I get my pump done I will be specifically asking for these spring to be replaced regardless.
 
Antony said:
Ian I'll tell what I know, hopefully it answers your question.

Most systems be it mechanical or electronic will advance the timing on a cold start up under till warm at idle. The major advantage of doing this is keeps the engine burning clean, no or minimal white smoke.

I would expect to see higher EGT's with a advanced engine vs retarded. The further you inject fuel before TDC you are then expecting the engine to work against it and compress somewhat the combustion process taking place. The closer you get to TDC or after the less time the injected fuel has to burn and you get a weaker, cooler combustion. That results in less power, so less preformance.

You'll generally find if your diesel is under preforming and its not a fuel delivery issue you'll drive round, heavy foot and use more diesel.
Click to expand...

Antony,

I was thinking more in terms of a pump that has had the ACSD removed, and the effects of pump timing on cold starts. I don't expect you guys deal with cold starts a great deal in NZ though, lol.

So advanced timing for improved performance, but you'll likely see higher EGT's as a side effect.
 
Awesome thanks for the link @diby 2000

also did you notice and difference with the pusher pump?
 
IanB said:
Antony,

I was thinking more in terms of a pump that has had the ACSD removed, and the effects of pump timing on cold starts. I don't expect you guys deal with cold starts a great deal in NZ though, lol.

So advanced timing for improved performance, but you'll likely see higher EGT's as a side effect.
Click to expand...

With the ACSD removed I definitely expect to see so white smoke on start up on cold days, lower idle but nothing to problematic. In the deep south we see our fair share of cold weather in the winter :-)
 
diby 2000 said:
Found it HERE
Click to expand...

Interesting read. I had a look through the Denso service bulletins today and there is nothing on this particular fault. If its a fault thats developed over time then spring fatigue sounds plausible. Most likely when you were checking idle recovery on the test bench and compared old spring to new you would pick it up. I wouldn't expect to many shops would pick this up though unless you specifically told them to change the springs out. In saying that they aren't expensive and I'll be replacing them now that Im aware of the potential fault. Cheers for pointing it out :-)
 
IanB said:
Antony,
So advanced timing for improved performance, but you'll likely see higher EGT's as a side effect.
Click to expand...

Sorry to be 'That Guy', but, in my experience with diesels, advanced timing means cooler EGTs but a higher load on the cooling system. Retarded timing I have found to bring EGTs up. My understanding is that the earlier the fuel is injected, the more complete the combustion 'event' is when the gases are pushed out by the rising piston. This adds more heat to the cooling system though. Obviously, it's not the best idea though to advance timing excessively as that causes other problems. Gotta find the sweet spot. Someone like @Dougal or @gerg could probably give you a proper explanation of why as opposed to the above, but hopefully it kinda makes sense.
 
AussieHJCruza said:
Sorry to be 'That Guy', but, in my experience with diesels, advanced timing means cooler EGTs but a higher load on the cooling system. Retarded timing I have found to bring EGTs up. My understanding is that the earlier the fuel is injected, the more complete the combustion 'event' is when the gases are pushed out by the rising piston. This adds more heat to the cooling system though. Obviously, it's not the best idea though to advance timing excessively as that causes other problems. Gotta find the sweet spot. Someone like @Dougal or @gerg could probably give you a proper explanation of why as opposed to the above, but hopefully it kinda makes sense.
Click to expand...

No worries about being "that guy", like I said I havn't played with timing and egt's so to speak. I can only go off the theory I've been taught and opinions of other people in my industry I've talked too. When looking at emission control in modern diesel engines NOx levels are released in higher levels when higher peak temperatures are reached, it has been found advancing the timing can increase the NOx levels and retarding it lower them. This has been talked about on common rail courses I have been on so I'm confident peak combustion temperature is higher when timing is advanced but I cant argue with what you guys are seeing also. There is always going to be the optimum range for timing to be set at which you'll have the best mixture of performance, safety and emission control.
 
That was my understanding AussieHJ. Im just having trouble articulating it.
You are correct as well Anthony.
Aadvanced timing the heat is put to work pushing the piston down and is absorbed into the engine. It can delay the turbo building boost also.
Retarded timing the heat is blown out the exhaust and wasted. Will bring boost in earlier as the heat is going into the turbo

IanB is asking about EGTs not combustion temps
 
Peak combustion is certainly higher when timing is advanced, and I have been told that retarding timing improves NOx emissions as well.

When the fuel pump on my 1HD-T was headed south it couldnt hold its advance as revs increased, with the timing at the most advanced side of spec, it made acceptable torque and power until about 2200 rpm, and then it just started to drop, she'd smoke like a steam train and egts would go through the roof. By 3600 she'd only be making about 90 rwkw (23psi intercooled, 21:1 AFR) and you just couldnt control EGTs.

With a freshly built XXi pump designed to fuel the Gturbo, the same fuel load made 154rwkw at 3600 and EGTs maxxed out at 700C pre turbo. The only thing we could work out making the difference was the advance being held throughout the rev range properly. Adjusting the timing on the pump confirmed this, but obviously making nowhere near as much difference as basically no dynamic (is that the right term) advance.
 
Antony said:
With the ACSD removed I definitely expect to see so white smoke on start up on cold days, lower idle but nothing to problematic. In the deep south we see our fair share of cold weather in the winter :)
Click to expand...

I have run both with ACSD and without. I can confirm Antony's suggestion. At just above freezing temps the 1Hd-T gives just a small amount of white smoke and a lower idle without ACSD, however it starts and runs Ok, It only takes 10 or so seconds to overcome this, and i think the afterglow will run up to 120sec in these conditions.

I had the ACSD removed as a preventative during the pump rebuild, but if you can be sure it is reliable and see cold starts I would keep it. I do believe only the early model 1HD-Ts got the ACSD in Aus.
 
You must log in or register to reply here.

Share this page

Back
Top Bottom