The Official 1HD-T/FT Fuel Pump Mod Tuning Thread (5 Viewers)

[diby 2000]

This is great info!
I might suggest this sort of info might be best concentrated into another OFFICIAL ROTARY PUMP MODS thread.
It's early days but I can see the benifit here for people who are willing to dabble inside the pump.

 

[Mcreight911]

It was my understanding that case pressure was depending on rpms, not by main fuel screw.

As you approach max fuel screw setting funny thing happen with timing advance

Your right I worded what I wanted to say incorrectly . In simple terms the volume of fuel that doesn't go to the injectors acts on the timing advance mechanism. If more goes to the injectors less goes to the advance mechanism, so you inject more fuel but at a more retarded degree of crank rotation

 

[Mcreight911]

The timing mechanism is controlled by the IP's case pressure. With a constant throttle position as the engine speed increases, the injector pump case pressure increases. The pressure increase overcomes the timing mechanism spring and advances the injection timing.

The case pressure is determined by the vane pump rpm and the pressure relief-valve.

The fuel screw doesn't directly effect case pressure but it dictates the travel limit of the leaver that moves the control collar. The control collar uncovers/covers the spill port in the delivery plunger .

The more the spill port is covered the more fuel flows to the injectors. The more fuel that flows to the injectors the less volume there is build case pressure



When you wind the fuel screw up on some pumps (mainly worn out ones) the vane pump can not maintain the flow need to supply the injectors and build suffecnt case pressure to fully act on the timing advance mechanism. bigger injectors can cause timing advance problems as well

Hope this makes sense, I'm not good at explaining things and it's way past my bed time .

 

[remy]

I understand. That's how I had it in mind. I've hooked op a pressure gauge a few times to measure case pressure. You can see very well the pressure drops a lot when flooring. It comes back in a few seconds when more fuel is sucked by the vane pump to maintain case pressure. Hard to say what the actual timing is. I was looking for a piezo clamp element to hook up on the first fuel line to compare with the pump rpm sensor. So you can see the drift of the timing. But that piezo stuff is so expensive.

 

[diby 2000]

The timing mechanism is controlled by the IP's case pressure. With a constant throttle position as the engine speed increases, the injector pump case pressure increases. The pressure increase overcomes the timing mechanism spring and advances the injection timing.

The case pressure is determined by the vane pump rpm and the pressure relief-valve.

The fuel screw doesn't directly effect case pressure but it dictates the travel limit of the leaver that moves the control collar. The control collar uncovers/covers the spill port in the delivery plunger .

The more the spill port is covered the more fuel flows to the injectors. The more fuel that flows to the injectors the less volume there is build case pressure



When you wind the fuel screw up on some pumps (mainly worn out ones) the vane pump can not maintain the flow need to supply the injectors and build suffecnt case pressure to fully act on the timing advance mechanism. bigger injectors can cause timing advance problems as well

Hope this makes sense, I'm not good at explaining things and it's way past my bed time .

I think this is exactly what is happening with my pump right now.
I have the timing set right on the most advanced side of spec, but now that I can build over 30psi of boost, I have wound the fuel screw in for more go. I have found that even at 25:1 AFR at 33psi, I am reaching 750c pre turbo EGTs. I assumed this was because of a timing issue. This info confirms my thoughts.
Note- I don't know for sure how many ks are on my pump and injectors, I have put 140k in them in the 11 years that I have owned it but there was fresh paint marks on the pump way back then, and I was told by the steeler (car dealer) that it was just rebuilt.
I also have a walbro lift pump installed, but it only has 5/16 or 3/8 ports in and out. I'm thinking maybe that could be restricting the volume of fuel getting to the pump. When I find some time I plan on removing it and seeing what difference it makes, if any.

 

[remy]

Do you run a intercooler diby?

Was just digging into some denso spec sheets. Case pressure should be 843,4 kpa = 122psi on 1800 rpm pump speed and 17psi boost pressure. (1HDFT) So that's a tad higher than my pump was. Highest i've seen was 90 psi driving 195kph.
I cant find a relationship on case pressure and timing. Only on timer piston travel and pump speed by a given boost pressure.

 

[diby 2000]

Do you run a intercooler diby

Yes. I have a Safari intercooler with some pipework changes.
I have not tested the efficiency at these boost levels but I was impressed with it's performance at up to 17psi.

Do you run a intercooler diby?

Was just digging into some denso spec sheets. Case pressure should be 843,4 kpa = 122psi on 1800 rpm pump speed and 17psi boost pressure. (1HDFT)

That would be at 3600 engine rpm correct?

Where do you tap off to measure case pressure?

 

[remy]

Yes pump speed is half the engine speed. I tapped in on the ACSD cover plate as it was removed.

I found the EGT lower, 650 degree C on max speed on 20psi 27 AFR with good intercooling and 20 degree C ambient. I just cant get more fuel so I dont know the pump is worn or it is at is max level.

 

[diby 2000]

At 15psi, with the same cooler, about 30c ambient, I found around 21:1 AFR would result in about 750c pre turbo. 22:1 would sit around 700c.

I'm thinking the pump advance is suffering trying to supply the volume of fuel I'm asking if it as per the previous posts, and this is how I'm reading the higher EGT at leaner AFR.

 

[remy]

Strange that double the boost and even lower AFR's wont lower max EGT's. It is not very easy to measure dynamic timing. You'll need a TDC or some crank/cam pulse to compare the injection event with. Or maybe a gauge on the timer piston.

 

[diby 2000]

Honestly I think measuring the dynamic timing might be above my budget and abilities at this stage. If I ever find the time I might try reducing the boost and fuel to a lower level and see how it all responds.

I'm convinced that the high EGTs are a result of retarded injection timing when trying to supply lots of fuel. I'm thinking this might be the reason that some people (like Gturbo) only run to about 27psi with stock pump/injectors. I have not found a good reason for this despite asking questions on many different media. I assumed it was the fuel delivery that was the problem, I just didn't think it would show itself as a retarded injection timing issue. It does all make sense though.

 

[remy]

On the side of the pump is a cover the timing piston. For the cummins guys is a spacer available to give more dynamic timing. On some 1hd pumps is just a cover plate, on some is a cover with adjusting screw. I've tried once to undo the screw so give the piston more space to move but didn't make any difference. Should be possible that the pump wasnt able to make the timing in the first place. Always a guess without having the ability to measure it.

 

[diby 2000]

Another question that I have thought of recently. Can we utilise the ASCD timing advance system (once removed), with a boost operated actuator to advance the pump injection as the boost rises?
I assume the pump does this to some extent anyway but I don't know if it does, how it does it.

Would this be beneficial?

My thinking is regardless of rpm, at low boost the timing is set to inject at the right time but as the boost level rises, the volume of fuel injected rises also. As I understand it the injection timing does not change as the volume changes so all the extra fuel is added after the initial injection. If exaggerated to understand what I'm referring to, this would mean the extra fuel could still be added even by the time the piston has moved down the cylinder far enough for the exhaust valve to open. This means some still burning fuel would be leaving the cylinder and raising the EGT.

 

[remy]

Timing should be rpm related, not boost. Otherwise its knocking on low rpms with boost. You can add some timing off course, but thats where the efi comes in. I share your thoughts on inject fuel earlier instead of later on high rpm. Thats where the cummins timing spacer is for. You can maintain static timing for low rpms and allow more timing on high rpm while inject more fuel. Works maybe on our pumps as they are quite similar.

 

[Mcreight911]

I think this is exactly what is happening with my pump right now.
I have the timing set right on the most advanced side of spec, but now that I can build over 30psi of boost, I have wound the fuel screw in for more go. I have found that even at 25:1 AFR at 33psi, I am reaching 750c pre turbo EGTs. I assumed this was because of a timing issue. This info confirms my thoughts.
Note- I don't know for sure how many ks are on my pump and injectors, I have put 140k in them in the 11 years that I have owned it but there was fresh paint marks on the pump way back then, and I was told by the steeler (car dealer) that it was just rebuilt.
I also have a walbro lift pump installed, but it only has 5/16 or 3/8 ports in and out. I'm thinking maybe that could be restricting the volume of fuel getting to the pump. When I find some time I plan on removing it and seeing what difference it makes, if any.

Could be lack of hi rpm timing could be
High emp could be the lift pump fittings
5/16 is a bit small .

 

[DancesWithMutts]

I wonder if I am having something similar going on. My EGT's really run away as I approach 3k. Under normal driving it's 3rd gear (auto) where I have to be careful. I need to get a AFR meter to get more data.

 

[mudgudgeon]

There is an internal timing adjustment on the pump. Near the ACSD.
I played with it trying to get a 1HZ pump to work on a 1HD-T. (1HZ is timed differently)
To be honest, I don't really understand how it works, nor how to measure any change

 

[vwluv10338]

So my project yesterday was to build a 3" downpipe to replace the stock one which connected to a 3" exhaust at the B-pillar. I would have thought it would have just spooled earlier and leaned out some but it seemed to have the opposite effect. I had the truck tuned pretty well and the other week I drove it through the mountains to give me a good idea of how it's running under load. After installing the pipe it seemed to spool slower and was blowing more black smoke off the line. I hooked my boat up and have been driving around messing with the tune. I turned the fuel pin off of the max which is where I had it. I then also reduced the cam plate to the minimum from the maximum which seemed to help and be the opposite of how it always acted. Before adding cam tension increased my spool. Maybe I'm thinking of it incorrectly but I don't see why this change would seem to make my off-boost rich.

My ended up purchasing a 7MGTE Supra down pipe as I wanted to go turbo back and this gave me the turbo flange, flex pipe, rear connector, and some stainless to work with. I had to buy a v band and a 90 elbow to complete it. If I did it again I would probably just go from the cast turbo outlet because it was a lot of extra work for that bit because I had to cut out the EGR plate but it does leave me with a port if I want to add a wideband later. My first time welding stainless. I used stainless wire in my MIG and my chop saw. It's not super pretty but local fab shops wanted an arm and a leg. One shop said it would be 3/4 to a full day at $75/HR to make it. Hell, I have never done it before and it took me a full day.

Damn photobucket no longer lets to embed images and I can't figure out how to do it in Flickr
image

image

 

[mudgudgeon]

After installing the pipe it seemed to spool slower and was blowing more black smoke off the line

Time for a re-tune.
You've made a change to a major part of the system. I think the fact you are seeing a noticeable change in black smoke is a good thing, it indicates the change is significant.
With no restriction in the exhaust, I would expect it to require less fuel to drive the turbo because there's less back pressure to overcome.
I think this explains why you are seeing more smoke off idle. I would also expect smoke to disappear quickly as it comes on boost.
If you could data log what's happening before and after, I think you'd find you'd have lower exhaust manifold pressures to produce the same boost.

You may need to paint the aneroid pin and figure out what you're starting with, then start over with the tuning process.

 

[mudgudgeon]

I've been adding pics by uploading the file directly to mud, not using photobucket etc. Photo bucket has been a total ballsack to use for ages now.