ducki
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« on: April 04, 2013, 08:34:48 AM »
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Hi,
how can I measure the air mass when the engine no air mass meter (MAF- sensor) has.
The engine has only one T-MAP sensor, measures the pressure and the air temperature downstream of the turbo.
The air mass is calculated in the ECU. My engine tester can not read this data.
I need the air mass for the tuning.
what can I do?
Engine is a Ducato 2,8jTD Diesel without EGR. ECU is an EDC15C7.
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« Last Edit: April 04, 2013, 08:36:54 AM by ducki »
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jaymemaurice
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« Reply #1 on: April 08, 2013, 06:20:46 PM »
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Do you really need the air mass for tuning??
I mean, the ECU is calculating based on pressure and temperature.
Since the size of the cylinders and walls of the intake do not change, it probably just uses a map to calculate the corrections on amount of air that will go into a cylinder at a given pressure. If you were to tune the ECU you would be tuning based on those values. Those values probably loosely fit a calculation based on the size of the cylinders corrected by the duration of the intake valves, the duration they are open, and the flow of the intake system.
I think more details about the car, what you are trying to tune for etc. may be helpful for the community to help you out.
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ducki
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« Reply #2 on: April 09, 2013, 03:30:13 AM »
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Hi,
I know that already. It helps me but also further, to determine the mass of air that comes with every stroke in the cylinder.
From the turbo maps I can not see the air mass.
How does it help to know that the displacement / cylinder is 700 cm ^ 3 and the max. Turbo pressure is 1bar.
Therefore, I can not calculate the real mass of the air coming into the cylinder.
regards
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Rabbid
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« Reply #3 on: April 09, 2013, 03:43:27 AM »
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n = PV / RT
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nyet
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« Reply #4 on: April 09, 2013, 09:46:56 AM »
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How does it help to know that the displacement / cylinder is 700 cm ^ 3 and the max. Turbo pressure is 1bar. Because if you know the amount of air moved by every cycle of a piston, and the density of that air, you can calculate the mass of air moving through the motor at a given RPM Therefore, I can not calculate the real mass of the air coming into the cylinder.
Of course you can calculate the real mass of the air coming into the cylinder. |
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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sn00k
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« Reply #5 on: April 09, 2013, 10:43:47 AM »
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Because if you know the amount of air moved by every cycle of a piston, and the density of that air, you can calculate the mass of air moving through the motor at a given RPM
Of course you can calculate the real mass of the air coming into the cylinder.
..assuming fillrate/VE = 100%..? ..or in this case closer to 200%..?  well, you could just temporarily take a suitable oem MAF from sau an audi, and hook it up to the turbo intake.. then use the conversion table from volts - flow for that maf, then you would have an accurate number to go on. |
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« Last Edit: April 09, 2013, 10:50:49 AM by sn00k »
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ducki
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« Reply #6 on: April 09, 2013, 10:44:32 AM »
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In theory.
In practice that's on so many factors, such as:
variable flow resistor (valve area), temperature of the charge air, charging time, etc. dependent.
If I use the gas equation, then I can only guess.
Consider:
Temperature 50 ° C; pressure 2bar.
So I get a 700cm ^ 3 cylinder, an air mass of 1.5 grams
That's but extremely inaccurate, so you can not tune it - or??
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ducki
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« Reply #7 on: April 09, 2013, 11:00:57 AM »
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well, you could just temporarily take a suitable oem MAF from sau an audi, and hook it up to the turbo intake.. then use the conversion table from volts - flow for that maf, then you would have an accurate number to go on.
Yes! This is correct. Only this effort I would not do with such a simple turbo diesel with unregulated turbo and without EGR. I thought, someone knows a map when EDC15C7, where I can see the speed-dependent calculated air mass. |
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nyet
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« Reply #8 on: April 09, 2013, 11:37:42 AM »
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That's but extremely inaccurate, so you can not tune it - or??
Depends what you are going to use the data for. |
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ME7.1 tuning guideECUx PlotME7Sum checksumTrim heatmap toolPlease do not ask me for tunes. I'm here to help people make their own. Do not PM me technical questions! Please, ask all questions on the forums! Doing so will ensure the next person with the same issue gets the opportunity to learn from your ex
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ducki
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« Reply #9 on: April 10, 2013, 01:39:03 AM »
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Depends what you are going to use the data for. I do not understand.  I can not just accept a theoretical fillrate of 100%, and tune with the calculated air mass completely independent of the rpm. Am I wrong here?  Then I might as well increase the matching percentage maps |
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sn00k
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« Reply #10 on: April 10, 2013, 03:39:48 AM »
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so, if i understand you correctly, you are asking for a VE-table for the engine..
i have no idea on how the EDCs and diesels work, and so i wont be of much use here..
but the VE-table in many ECMs is one of the things, perhaps THE one thing, that you will have to tune yourself.. you can calculate it roughly within -+5-10% if you know what youre doing, but you would still have to tune it based on AFR, MAF or in this case EGT..
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ducki
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« Reply #11 on: April 10, 2013, 04:37:29 AM »
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but the VE-table in many ECMs is one of the things, perhaps THE one thing, that you will have to tune yourself.. you can calculate it roughly within -+5-10% if you know what youre doing, but you would still have to tune it based on AFR, MAF or in this case EGT..
The VE-map shows me only the correction factor of IQ on the rpm. This factor is even at higher rpm's to zero. He does not reflect the Fillrate to the air mass. To measure the exhaust gas temperature (EGT) is possible for me so bad. I have no idea |
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prj
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« Reply #12 on: April 10, 2013, 05:33:40 AM »
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What's the big deal?
Add boost until the turbo can't anymore, and the IAT's go up.
Add fuel until either EGT goes up or you are not happy anymore with the smoke.
This is diesel, not rocket science.
Of course calibration of the injection start is a different story - for this you will need cylinder pressure measurement to do it right.
A dyno can also be used, but care has to be taken as not to over advance and cause too high cylinder pressures.
But unless you have replaced the nozzles, you don't need to do this, or you can extrapolate the stock map.
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ducki
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« Reply #13 on: April 10, 2013, 06:53:15 AM »
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Hi mate, It is kind of what you submit to me for suggestions.  The car is a camper and not a race car.  Sure the diesel is not rocket science, and I had it tuned up before 2 years before. Ran like the devil. Unfortunately I am now twice the clutch broke.  Now I have made a much weaker tuning, (much less torque but more power) and, of course, changed the SOI slightly as the duration is 160 uS longer. Now I said a tuner, so that's impossible. I first need to Airmass. I can not measure the above mentioned reasons. Calculate Airmass is 1,5 grams /cylinder by full Turbopressure (its no VTG!!) It results in a theoretical maximum IQ of 103 mg Diesel. Therefore, the whole dispute. The IAT I can not even measure - and why Which I can not influence anyway, and is also dependent on the weather (air temperature because of intercooler). I do not have a dyno, and get to the big car and not purely in normal Dynos.  Cylinder pressure measurement, etc, this is all far too costly for the little bit of tuning, what I want to do .... And now |
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« Last Edit: April 10, 2013, 10:35:47 AM by ducki »
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prj
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« Reply #14 on: April 12, 2013, 07:22:53 AM »
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You don't need any airmass measurement to tune a diesel. Many OEM diesels run with just a MAP sensor. The only thing the diesel ECU needs airflow for really is to limit smoke. If there's no MAF you can easily limit IQ based on MAP and IAT. I think you need to spend less time typing stuff and looking for things you THINK you need (which in reality you don't) and more time tuning  Just add EGT gauge and add IQ until EGT goes too high or it starts to smoke. Easy. With diesel the IQ limit is usually amount of smoke that you are comfortable with. If you want to do it a bit more scientific, put a wideband gauge on it, and aim for 15-17 AFR, depends how much smoke you want. 15 is going to smoke quite a bit, 17 is going to be almost smoke free. |
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« Last Edit: April 12, 2013, 07:24:43 AM by prj »
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