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Discussion Starter · #1 ·
In the near future I am planning on replacing my turbo and intercooler, as they are currently the original items and are high in the km’s. I have had boost and egt gauges for a long time and have a good understanding of what my setup does. To further this understanding, prior to the new turbo and cooler, I have started to think about air fuel ratios. Subsequently I have purchased a Bosch LSU4.9 wideband 02 sensor, a Techedge 2J9 wideband controller and a LX1 display.

Some quick back ground information: A long time ago I made a small increase to the max fuel screw but have since realised there are better ways of doing things. I have started to make small adjustments to the boost compensator; so far I have cleaned up the mix from idle whilst still maintaining a mid and top end that I am happy with. Previously a puff of black smoke would be visible out of the exhaust when getting into it, now almost nothing. However, in taking out some off boost fuel I have certainly noticed the max boost decreased and turbo spool is slower.

Back on track now - Some initial observations from the air fuel ratio gauge are:
1. Idle 27/28:1
2. Normal driving on flat ground 22:1, give or take an af point.
3. 80-85% throttle up a hill 17:1
4. Full throttle up a hill will momentarily drop into 16:1 but will rise back to 17/18:1 very quickly.

At 16:1 I start to notice smoke out the exhaust and in my ‘noob-ness’ to diesel air fuel ratios would consider that a ‘dirty’ mix. All this leads me to the point of wondering what is an ideal ‘on power’ diesel air fuel ratio. If I had to guess I would say 18/19:1 however I am not 100% sure and would welcome some insight into the matter.

Thanks
 

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nissan
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Some interesting reading:

Diesels can operate with a broader range as rich as 15:1 or as lean as 60:1, however, going richer than about 22:1 to 25:l produces excessive temperature, soot, smoke, and poor fuel economy.
Banks Power | Understanding Today's Diesel

The air/fuel ratios for diesel engines under full load are between 17:1 and 29:1, while when idling or under no load, this ratio can exceed 145:1.
AutoSpeed - Common Rail Diesel Engine Management, Part 1
 

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It is a very interesting thread. I was thinking of the pump timer, governor characteristics. It is also essential characteristic as well as the injection timing and injection quantity of the fuel. even more interesting to consider this air-fuel ratio. thank you
 

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In the near future I am planning on replacing my turbo and intercooler, as they are currently the original items and are high in the km’s. I have had boost and egt gauges for a long time and have a good understanding of what my setup does. To further this understanding, prior to the new turbo and cooler, I have started to think about air fuel ratios. Subsequently I have purchased a Bosch LSU4.9 wideband 02 sensor, a Techedge 2J9 wideband controller and a LX1 display.

Some quick back ground information: A long time ago I made a small increase to the max fuel screw but have since realised there are better ways of doing things. I have started to make small adjustments to the boost compensator; so far I have cleaned up the mix from idle whilst still maintaining a mid and top end that I am happy with. Previously a puff of black smoke would be visible out of the exhaust when getting into it, now almost nothing. However, in taking out some off boost fuel I have certainly noticed the max boost decreased and turbo spool is slower.

Back on track now - Some initial observations from the air fuel ratio gauge are:
1. Idle 27/28:1
2. Normal driving on flat ground 22:1, give or take an af point.
3. 80-85% throttle up a hill 17:1
4. Full throttle up a hill will momentarily drop into 16:1 but will rise back to 17/18:1 very quickly.

At 16:1 I start to notice smoke out the exhaust and in my ‘noob-ness’ to diesel air fuel ratios would consider that a ‘dirty’ mix. All this leads me to the point of wondering what is an ideal ‘on power’ diesel air fuel ratio. If I had to guess I would say 18/19:1 however I am not 100% sure and would welcome some insight into the matter.

Thanks
I think most would consider that a fairly good overall tune.
Much below 17-18:1 at full load will give you some EGT dramas and top end at 22-24 is nice and clean.
Most common guys chasing a good overall tune will be in the vicinity of 15-16 under full load down low ( maybe some will go a little dirtier ) cleaning up to 17-18 in the mid range and 20-21 at the top end.
Some like to keep it around 18-19 under full load though for a max power tune.
It very much depends on the turbo set up you are using and what you want out of it.
Some combo's require alot more fuel down low to get them on boost early while others will do it quite cleanly. You are doing it the right way though SW1, get a meter and tune it until YOU are happy with it. YOU are the only one that can say if you are happy with the results.
You will find when you change combo's that your current settings will probably be way out.
Just keep tuning until you get what you want. :D good luck.
 

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nissan patrol
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I feel proud that companies are finally catching on to AFR tuning on diesels. No more bashing my head against a brick wall hopefully!

Far to many times ive been told by reputable companies that im an idiot for using AFR and not just looking at EGT :(

SW1: Those controllers only read up to 30:1 (if you ask for it) The standard WB02 setups only go from 10-20:1

I think the 22:1 at cruise is the biggest problem for you.
Cruising range is about 25-30kw, which most diesels will do at around 26:1+++

An ideal full throttle mixture is around 21-22:1. This is of course for maximum engine longevity.

I normally aim for 16.5:1 on boost ramp (1000-1800rpm), 23-24:1 at maximum torque (1800-2100rpm) and falling to no richer than 18:1 at maximum rpm (4000rpm) if you have a stock turbo and bad or no intercooler.

I personally think the tune is overly rich for a compensated pump.
 

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Discussion Starter · #9 ·
Here you Scuba.

2 x 100% take offs, followed by a 80% take off.

Ecutalk gauges: rpm (top left, major scale 1000), speed (top right, major scale 20 kp/hr), water temp (middle left), volts (middle right), actual timing (bottom left), injection solenoid duty cycle (bottom right).
Ecutalk was reading 100 rpm up and 4 km/hr down compared to dash.

Mechanical gauges: oil pressure (left), boost (middle, major scale 5 psi) and PRE turbo egt (right, major scale 100 c, vertical mark is 500 c).

MVI_5356_zpsc4a4a785.mp4 Video by landssa1 | Photobucket

I know the tune is not perfect and I know the standard turbo has its limitations, 99% of the time it does not get driven like that.
 

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Discussion Starter · #10 · (Edited)
Those controllers only read up to 30:1 (if you ask for it) The standard WB02 setups only go from 10-20:1
My controller is using the 2J9 firmware, I know this as I flashed the firmware myself. So I am not 100% sure as to what your getting at.

I personally think the tune is overly rich for a compensated pump.
Yes I agree. I have stated above I have been taking fuel out in small steps. Obviously I am not a pro, so progress is in small steps. I didnt think the mix was WAY rich, though I may be wrong.
 

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Well its not miles out really.

But like I said somewhere in the vicinity of 20-22:1 AFR at full throttle is what you should be aiming for if its a daily driven car that tows.

If its a dirty old comp rig. or never has constant load 16:1 and it will probably survive.

It all comes down to tuning it to what the use of the vehicle will be.
 

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Thanks SW1, It is very hard to tell how it is behaving down low because the engine is revving too quickly. Need more load on the vehicle to simulate a slower load rate, I think the sensor cannot give you real time figures quickly enough. By the time the engine has gone to 16:1 and started to make boost the rpm has picked up and sensor is now reading 17 or so.
I think DT is right, ( obvoiously he has lots more knowledge on this than me ) but the top end is probably a bit dirty, But if it was mine I would probably still put a little bit more in to it down low, right off the bottom.
But you would need to do the tuning with more load on the car, I always did mine with the 2.3T wakeboard boat behind mine, to simulate a slow ramp rate. Try loading it up and see how it goes.
If it is no different, maybe try a going down with the star wheel a bit more and perhaps putting one thin shim back under the comp. THis should give you slightly more on initial spool, and also take a little bit out at full load. Just my 2c though.
DT feel free to correct me if you think this is not right.
 

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Discussion Starter · #13 ·
But like I said somewhere in the vicinity of 20-22:1 AFR at full throttle is what you should be aiming for if its a daily driven car that tows.
no worries, advice taken on board.

If its a dirty old comp rig. or never has constant load 16:1 and it will probably survive.
rarely tows, even rarer that it gets driven boy racer style, further improvements to be made.


:eek:
 

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Discussion Starter · #14 ·
you would need to do the tuning with more load on the car, I always did mine with the 2.3T wakeboard boat behind mine, to simulate a slow ramp rate. Try loading it up and see how it goes.
If it is no different, maybe try a going down with the star wheel a bit more and perhaps putting one thin shim back under the comp. THis should give you slightly more on initial spool, and also take a little bit out at full load
Thanks again Scuba.
The car is not daily driven, so there's not a big rush. Next opportunity I get I will give your advice a go. Gotta find some load now :D
 

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Discussion Starter · #16 · (Edited)
DT I have just looked through the first 15 pages of your gtx2863 thread looking at the afr's for every dyno run posted. Can you further explain your above comments given that in the graphs I am lucky to see afr's go higher than 20-21? You said at cruising I should be seeing at lot higher than 22, the best I have achieved is 23.5. The only time it goes beyond that is when the road is slightly down hill. I was able to raise the hill runs from 17 to 19 (including wot).

The cruise in question is 80 km/hr 5th gear.

I have never spoken to diesel central but when his dyno graph afr's top out at 20 for 150 kw's, that says something me.
 

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Discussion Starter · #17 ·
Dont forget this real world driving: 285's, 2" lift, roofrack, winch bar, winch with steel wire, twin tyre carrier, rear draws, yada yada yada.
 

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Dont forget this real world driving: 285's, 2" lift, roofrack, winch bar, winch with steel wire, twin tyre carrier, rear draws, yada yada yada.
And therein lies the problem, dyno's do not allow for weight , wind or drag coefficient, changing road friction, changed tyre pressures and a host of other things. They simply give you information from a set number of known parameters, they should only be used as a guide to making changes.

Sent from my ASUS Transformer Pad TF300T using Tapatalk HD
 

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DT I have just looked through the first 15 pages of your gtx2863 thread looking at the afr's for every dyno run posted. Can you further explain your above comments given that in the graphs I am lucky to see afr's go higher than 20-21? You said at cruising I should be seeing at lot higher than 22, the best I have achieved is 23.5. The only time it goes beyond that is when the road is slightly down hill. I was able to raise the hill runs from 17 to 19 (including wot).

The cruise in question is 80 km/hr 5th gear.

I have never spoken to diesel central but when his dyno graph afr's top out at 20 for 150 kw's, that says something me.
Like I said, each setup is tuned to suit the purpose for which is was built.

That truck has a lightweight tray, no accessories, does not tow and was just for the guy to have a bit of fun off road.
Probably no longer than 15-20seconds at full throttle is ever seen.

All of those graphs are 100% throttle on the dyno. Anything at cruise in that thing is around 28-30:1 for the 20-30kw it takes to hold speed at 80kph.

Also the dyno's ramp rate can be setup to simulate extremely fast 1st gear acceleration runs, or even holding the car at 100% throttle, 3500rpm top gear for as long as you want or anywhere in between.

Knowing how to use that tool properly will make the world of difference to the tune.
 

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Discussion Starter · #20 · (Edited)
I would like to see a print out of afrs on the dyno then a video of the same car and its afrs in real world driving. For it to mean anything the key accessories and tyre size would need to be listed so weight can be estimated.

In adjusting the amount of fuel I am injecting I have in many steps gone from rather dirty to cant maintain 80 up a hill and have to drop down to 3rd gear, from what I have seen the only time 28 comes up is either idle or light coasting on a slight down hill.

If nothing else this is making me way more keen to seen the difference in afrs with the new hardware.
 
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