Fuel twiddling on the 1HD-T engine

[Jon Wildsmith]

For boost pressure you just need to connect a gauge to the inlet somewhere post turbo. It's unlikely to be that but might be worth checking. At 1800 RPM you should be getting lots if not full boost but if there's not enough fuel going in you won't be getting enough boost either so a bit of a catch 22 really. I know it's nice to do these things ourselfs but why don't you take it for Julian V to have a twiddle with, I will be with mine soon

 

[Chris]

Essentially Jon, because it's rather a long way from me. But worth thinking about. I know he has the twiddler's finger. Maybe I need to combine it with something else. I am planning a canoe trip down the river Wye.

Missed out on a beautiful hand-built wooden canoe this weekend.

Chris

 

[Julian Voelcker]

I believe that the pumps have to be taken off & given to a fuel specialist's & they are then instructed to set up the pump, to give the maximuim performance obtainable from a great big lazy 4.2 diesel turbo.

Pump guys will only ever set the pumps back to factory defaults, you can only really 'tune' the pumps on the engine.

 

[Dave Docwra]

Julian, as I said instruct to them to obtain maximum fuelling not just factory set up...

 

[Julian Voelcker]

Julian, as I said instruct to them to obtain maximum fuelling not just factory set up...

They can't.

They only ever know about the injection pump. Yes I guess they can find out about the injectors and spray patterns, but then they need to know the injection timing, the piston shape, the engine capacity, valve timing, the compression ratio, etc, etc. They would need to know all this and a lot more in order to tweak the pump, which in reality they will never know and therefore no injection pump specialist will commit to tune a pump off the engine.

 

[Dave Docwra]

Hi Julian, I fully understand what you are saying, But in my experience there are certain companies out there that can work wonders with a rotary pump, 2.5di Transit Rotary pumps for example were never very good using default settings, but in the hands of a good pump specialist whom I am lucky to have one close by, using their own set up could transform the whole engine running capabilities.

I am sure that I have read somewhere & maybe it was on the South African Land Cruiser forum that there is or was a company specialising in getting the max from these pumps very successfully.

 

[Andrew Prince]

a good pump specialist whom I am lucky to have one close by

Close by in the UK, Dave - or in CT?

EDIT: Apologies for the OT Just trying to find out if there is a diesel pump expert in the greater London area.

Cheers,

 

[Chris]

Chaps, we're drifting slightly. Not unusual and here and all part of the chat, but this would make a good sticky if we can narrow it down to effective tweaking for the 12 valve engine. I certainly don't think that in my case I need to rebuild the pump. I am going to have a go at increasing the main fuel screw very slightly and see what effect that has. Tricky little blighter to get to I know.

In the mean time can anyone answer the question about the main fuel 'needle' as I'd call it. Towpack said that he'd rotated his. There are different profiles cut into the shank of the needle which engage with a pin. When I opened mine, there is no indexable diaphragm underneath the top cover. I am sure that there was only last truck. All there is is a black perfectly round rubber diaphragm which actually look a bit baggy.

Any clues on that one - not that I need to do that performance mod necessarily, just curious. I don't want to lift that up as the LCOOL instruction are very clear on what happens if you pull the pin right out.

Chris

 

[adrianr]

With regard to that diaphragm all i did was mark it and its current location on the pump

closed my eyes (forces you to pay attention to what you are feeling) and turned it first the the left and then to the right feeling for the area of least resistance. thats where it wants to be.

Good luck Chris, you will get it sorted.

 

[Dave Docwra]

Sorry Chris but I feel it is relevant in connecting to your lack of low down torque, I am convinced these pumps are set up conservatively for low emissions & engine longevity from the factory & a diesel pump specialist can get more from them. I also have to agree that Julian can get a great deal more from these pumps but unless you fully understand the vehicles like JV doe's you could be causing more problems.

Andrew, Wade diesels in Hoddesdon have always been good with rotary pumps & CAE of Chingford for inline pumps.

 

[Julian Voelcker]

I use RVS in Swindon for all our pumps and they have always done a great job, however the pumps will always come back at factory defaults and will need tuning up.

 

[pugwash]

It may be worth investigating what works with the landrover 200tdi- its essentially the same FIP with 2 fewre ports- in function, and form they are remarkably similar. The knowledge base for the LR diesels is already there, so might be worth tapping into as a good basis for "best practice".

Here is a very comprehensive report on how to tweak the fuel pump- without pictures unfortunately, but you'll get the drift:
http://forums.lr4x4.com/index.php?showtopic=31

this links to here:
http://dodgeram.org/tech/dsl/more_power/Power_ve.htm

You will see from the piccies just how close the bosch VE pump is to the denso pump- carbon copies basically!
This link also supports the link between the bosch pump and the LR pump (just in case you are worrying)
http://www.offroad80s.com/turbo-boost-p ... t2511.html

and also has a link to:
http://autospeed.com/cms/A_109306/article.html

 

[syche]

Hi All

i did fuel tuning in several toyota including my HDJ80 which is now doing fairly well spinning tires in 4wd with 3" exhaust, Graeme turbo and Crosscounrty IC.

If you increase the fuel not increasing the boost, your EGT will climb up severely and will arm your engine.

Increasing the boost without an IC will increase the intake temperature and therefore the EGT.

You can go to 0.85 / 0.9 bar (by adding washers on the waste gate support (2mm should be about that pressure if i recall right) or a turbo tap, also called boost controller) on the 80 without an IC and the lowering the aneroid spring nut to almost it's max. If you read the HDT manual you will have the factory height of this nut (the clicking one), and it is already close to the bottom on a 12V. take that down to almost it's max, then turn the aneroid to it's steepest slope.

At first do not touch the off boost cam on the aneroid cover. Give it a try, check your smoke and torque at very low rpm (up to 1200rpm). If no smoke at all and very limited torque at low rpm and no smoke while full boost revving up (passed 1600/1800rpm) you have to add a touch on the main fuel screw. This will increase your idle speed, go by 150 rpm steps, write down what you did (for possible reverse procedure if too much) and then adjust your idle speed and AC actuator.
if you have smoke under boost (acceptable not a train) but limited torque down low, you have to turn a bit the cam on the aneroid cover to push the aneroid down a bit while off boost. Go by steps it take time.

You have to make sure when you assemble the aneroid cover on the pump that the aneroid spring still push a bit before the cover got fully tight (the aneroid need to be pushed all the way up to it's off boost cam limiter when off boost). If not you have to lift the clicking nut a bit up to it does or turn the off boost cam on the aneroid cover. There are different spring height depending on the countries and emission regulation, so you can't make a rule, it is tests and understanding.

It is not a difficult thing for someone with minimum of understanding of how it works, just don’t do it in a hurry.

One more thing, check the wear mark position on your aneroid before you do anything, check on which slope it is and how high is it. Keep in mind that the aneroid move about 4~5mm to adjust your fuel from off boost to full boost. If you lower it too much by turning your off boost cam on the aneroid cover, you will reduce the aneroid stroke and therefore the fuel compensation capability which is not a good thing. Keep that in mind when you do yoru setup. Some time it is better to increase a touch the spring load by lifting or keeping the clicking nut in position and simply increasing the fuel on the main fuel screw in the back of the pump. (Which is not very easy to access on a 80)

Working around this you should be finding good to very good result but it take time and tests.

And on top of it, apparently you have an automatic gearbox, I don’t have experience yet on these, but the throttle cable to drive the gearbox also has quite some importance on the gearbox and engine response feeling, try to also check around that, this is quite a easy thing to do just find yourself the manual. Using google chrome/ translate you might find bits of info on my80isfantastic the French forum, the guys talked about it sometime ago

Have fun
Sylvain

 

[syche]

Now if you change turbo, add a good IC and 3" exhaust you can go way beyond that .

useful , not ,............ fun, definetly .

i was in algeria with a very simple tune as described before and a very small top mount IC with no scoop. So i had a touch over factory HP, and a touch more torque, but i was 2l/100km better on fuel consumption.
I never lacked power and could easilly climb dunes all modern kdj 90 and 120 manual or auto had very very hard time to get up to (same tires, similar load and all experienced friends. one was out of a factory 80 with 450 000km and could not believe how weak it's on road peppy kdj actually was in soft sand compare to his ex 80).

From factory the 80, 12V (24v needs a bit help) outclass most modern 4wd when it come to pure offroad torque, so mods are for fun

 

[Chris]

Quick up date on this [strike:13uicuic]argument[/strike:13uicuic] thread. Yesterday I turned the main fuel screw up by 1/8th of a turn. The boost click wheel already had 3 clicks on. Now, as I said many times, all I am after is restoring some of the 'go' that has been lost over nearly 2 decades. I never wanted a fire breather, nor to perform major surgery on the fuel and turbo systems.

There was a noticeable but slight up lift with that tweak. Today off road (off road? Blimey, more like off-track. Never seen such mud) I definitely had more umph. I didn't suffer from the same stall symptom. I was able to actually use the traction this time. OK still didn't get through every obstacle, but it wasn't for lack of being able to bury the throttle and get a response. I'm not planning any more than this, just nice to get a bit more verve back again.

Chris

 

[whereisgibson]

I have a basic question here, but I shall explain where I am first:

I followed the pictures here: http://www.tlocuk.co.uk/forums/viewtopi ... a75d7e12e5

(thankyou joinerman)

to find the OUT screw aka the main fuel delivery screw.

I marked where I started for reference. It was very stiff but it did undo. I managed to get it to move a little before hearing gurgling, at which point I did it right back up to where it came from.

To anyone that's not me, they will have spotted the problem... which is that the OUT screw isn't the screw to mess with. The more patient will have read the above link closer.

So what have I done? Is it a problem that a little gurgling has gone on?

edit: 'OUT' is the No.2 Nozzle Leakage Pipe from what I can see...
edti2: or the fuel outlet pipe?

 

[joinerman]

The other adjustment is the nut to the right & below the nut that says OUT

 

[karl webster]

As joinerman says....


The main fuel screw is to the right and under the out bolt you mentioned.

You will need a spanner or a deep 12mm socket on it and take it out and take off the shiny sleeve (hammer and slotted screwdriver) Best to put some paint on the screw so you know where the 12mm nut was before you started. When the sleeve is taken off put main fuel scre back into the pump then slightly turn in for more fuel.12mm is the locking nut.

All you have done by opening the out bolt is let air into the system but on the return side so no issues at all.

Karl

 

[Chris]

Yep, the one with the screwdriver slot in the end and the crimped collar around it. I just used a long screwdriver and prised the collar off with it in situ. There is a split in it - it's like the ring on a bird's leg. I pushed the blade in there and twisted. Really is better this way. Marking such a small item and putting it back precisely when only an 1/8th of a turn is needed just sounds like micro surgery


C

 

[IRLGW]

I had a 'go' at this mod today as like a few other people I nearly got swiped a few times at roundabouts and pulling on to main roads in my 12v due to a lack of power real low down. Up high its grand and the mpg has always been excellent.

First up was to rotate the boost compensator. i went for the three clicks but the toothed wheel was so high in the enclosure that I could hardly see it and had to work with my left hand and a little blind. I wasn;t quite sure if the screwdriver jumped or I got the the click but guesstimated 3 turns and then did the 180 turn on the hex screw.

I didn't notice a massive improvement (and had not adjusted the main fuel screw yet hoping that I can save the fuel economy because the truck was ok up the range) but did feel that the power was topping out at 2000rpm and there was no more acceleration.

After sleeping on it and re reading all the info on the web and forums I decided to go more on the toothed wheel and line up the aneroid screw (least resistance method) Most people reckon that on the 12v engine that the toothed wheel is already near the bottom but mine was actually near the top and I turned it down a fair bit although it hasn't yet stopped turning. I then took off the aneroid cover and did the rotating thing although I have to say that I couldn't confidently determine the point of least resistance. main fuel screw was still not adjusted.

I put everything back and went for a 50mile round trip. It felt that low low down performance was better (but this could have been psychological). In third gear at say 25mph the boost light comes on from about 1000rpm if I accelerate but again feels like its topping out at about 1800-2000rpm. Smoke was not noticeable in the mirrors but the engine doesn't feel as smooth.....


What to do next?
A) max out the toothed wheel, Double check the Aneroid position and turn the fuel screw 1/8turn.
B) Just turn the fuel screw 1/8turn.
c) Go back to as was.

There also sounds like a clicking coming from the fuel pump when the engine ticks over and again I think it has got louder since I made the adjustments.

Is it really unusual for the toothed wheel to be near the top on a 12v Manual- The whole fuel pump appeared un-molested (before I got to it) with the yellow paint intact and the metal collar on the fuel screw still in place. All I'm looking for is to have a fraction more low down and in mid range for towing and pulling out of junctions but don't mind going more if it doesn't disrupt the economy under normal driving...