Hi,
I have a little doubt about stock duration map in JTD 8V 115HP engine with EDC15C7. For 70mm3 of fuel and railP of 1400 bar there is greater duration than for 1350bar. This value for 1400bar and 70mm3 make no sense to me.

Look at duration table, red rounded values:


It looks even stranger if looking in 3D mode, where we can see that for 1350 and 1600 bar lines are almost linear. For values 1200, 1300 and 1400 there is almost linear values up to 65mm3, and after that goes much higher. For railP 1000bar and under, this jump appears even earlier, at 60mm3:


Does anyone knows reason for this? Is this value for 1400 bar and 70mm3 correct and how can for 1350bar and 70mm3 be lower value??

What formula to use when calculating duration for 1400 bar and let say 80 and 90 mm3?

This is driving me crazy...

Because x axys is not linear
look 65 - 70 - 70,20 - 70,30

similar - it works but not all in all correct

manfred wrote:Because x axys is not linear
look 65 - 70 - 70,20 - 70,30

This has nothing to do with question that I asked.

sike_145 wrote:Hi,
I have a little doubt about stock duration map in JTD 8V 115HP engine with EDC15C7. For 70mm3 of fuel and railP of 1400 bar there is greater duration than for 1350bar. This value for 1400bar and 70mm3 make no sense to me.

Look at duration table, red rounded values:

doi_jtd8v.JPG

It looks even stranger if looking in 3D mode, where we can see that for 1350 and 1600 bar lines are almost linear. For values 1200, 1300 and 1400 there is almost linear values up to 65mm3, and after that goes much higher. For railP 1000bar and under, this jump appears even earlier, at 60mm3:

doi_jtd8v_2.JPG

Does anyone knows reason for this? Is this value for 1400 bar and 70mm3 correct and how can for 1350bar and 70mm3 be lower value??

What formula to use when calculating duration for 1400 bar and let say 80 and 90 mm3?

This is driving me crazy...

So, no one have answer for this?

What about all you that tuned your JTDs? Didn't notice that irregularity or what?

To be clear if somebody miss understood:

70 mm3:

1127 uS for 1000 bar
978 uS for 1200 bar
948 uS for 1300 bar
871 uS for 1350 bar
897 us (!!?) for 1400 bar
795 uS for 1600 bar

This value 897 is obviously wrong and should be between 871 uS (for 1350 bar) and 795 uS (for 1600 bar).

I know what you mean. You asked the same question at alfaowner. I read several things which may explain this phenomenon. My problem is: i know what I've read, I understood what the authors said, but I can't explain it in my own words at least not in english. In german it is easier.

schokomanu wrote:I know what you mean. You asked the same question at alfaowner. I read several things which may explain this phenomenon. My problem is: i know what I've read, I understood what the authors said, but I can't explain it in my own words at least not in english. In german it is easier.

Can you try to explain, you can send PM to me, even on German, I'll found way to translate it.
Or point me to material where you found answers to this phenomena. I have seen many others duration map, and no one else have that strange values. I have even found newer version of ECU software for same engine but in alfa 147...and there are very similar values for IQ/railP pairs (so I think that can be programmed for same injectors) but there is no such phenomena. All curves are linear, there is no anomaly for longer duration @ 1400bar for 70mm3.

I'm very interested to found explanations for this. Currently, I have corrected values in my duration maps to be more linear, also increased TL to inject max of 80mm3 - because, with stock map and extrapolation, for 75mm3 and 1450 bar there is about 955 uS of duration...and now when I "corrected" values, that duration for 1450 bar means more then 80mm3. So, now I'm injecting a little lower amounts of fuel, but car still pulls very good but with less smoke. Few day ago I went to trip on highway, constant 140-160 km/h speed with short trips up to 190-200km/h (and that was uphill road)...and I didn't notice increase in engine temperature. It stays much under 90 degrees (and thermostat is OK, last year I replace it with new), outside temperature about 4-6 deg C.

Last three columns are the same and are linear - a feature limit the flow of fuel with the possibility of extension. That is the number of columns laid developers ECU unit; and programmers with limited Fiat injections nozzles 70. And for us it is an opportunity for expansion.

Deman wrote:Last three columns are the same and are linear - a feature limit the flow of fuel with the possibility of extension. That is the number of columns laid developers ECU unit; and programmers with limited Fiat injections nozzles 70. And for us it is an opportunity for expansion.

Hi Deman...yes I know that. Like I said before...maybe someone miss understand what I am asking. Ignore last two culumns (70,2 and 70,3), they are irellevant. Look at values only in 70,00 column, for railP of 1350, 1400 and 1600 bar.
It is:
871 uS for 1350 bar
897 us for 1400 bar
795 uS for 1600 bar

Question is, how can duration be greater for greater railP? This value of 897uS for 1400 bar does not fit here...should be lower than 871uS for 1350 bar (with increasing pressure it requires shorter time to inject same amount of fuel)

Possible errors specifically or not, is unknown. But this does not affect the original, because the pressure does not exceed 1350 bar.