boost duty cycle conversion - again..

[#84]

We have discussed this before, but as far as I know have not come to a final conclusion.

So, is the maximum duty cycle value 128 (80h) or 255 (FFh)?

I believe it is 255.

/A

[jimnielsen]

Hi #84 - I have been experimenting with the values in this table and Ive been pushing them higher because it hasn't really been giving the expected results... but I had believed that this bit of text..

" Max value for this map is 128 and not 8 bit max value of 256, as (128*100)/256)*2= 100%, so the value of dec 128 means the 100% duty cycle or 100% opening of the overboost valve which means the highest turbo pressure. But as the turbo pressure build up is dependant of turbo charger type, wastegate actuator stiffness and RPMs, there is no logical calculation for altering the values to get the desired turbo pressure. You have to try different values and make test runs.

written by 'wolf' I believe was the facts of the matter.

Anyway, I am going to be trying values up to and over 128 - so I will let you know the results..

jimn~

[arjunior45]

I was told that at Q4's bin there are certain lines- hex addresses that they 'correct' the boost delivery versus something. These should be at hex addresses : 760-8 to764-f {10103-10104} or 61-8 to 65-f {10105 immo}, going :

a} 760-8 to 761-7 {61-8 to 62-7} - different values in 10103
b} 761-8 to 762-7 {62-8 to 63-7} - same values for both of them
c} 762-8 to 763-7 {63-8 to 64-7} - same values for both
d} 763-8 to 764-7 {64-8 to 65-7} - in 10103 all values are 00
and
e} 764-8 to 764-f {65-8 to 65-f } - in 10103 all values are equally 00.

Does any one have any clue about them?

Nick

[#84]

I don't have aclue. I will check with my note sat home during the weekend. Maybe it is some regulator seetings.

I calculated speeds from the 8 last positions and got 7267 / 2441 / 1817 / 363 rpm. It doesn't seem to mean anything.

What I really miss is the function, or map, that controls the time the lower boost limit may be exceeded and the algorithm for lowering the actual boost to that level. However, I do not see a clear correlation between that function and the 4? lines you refreed to.

[arjunior45]

What I really miss is the function, or map, that controls the time the lower boost limit may be exceeded and the algorithm for lowering the actual boost to that level. However, I do not see a clear correlation between that function and the 4? lines you refreed to.

what do you mean for the map 'lower boost limit may be exceeded'? I can not understand you

Nick

[#84]

Nick,

With 'lower boost limit may be exceeded' I mean maximum stationary boost (h0670-h067f in 101.05 or h7660-h766f in 101.03/04). When you exceed this limit in lower gears obviously nothing happens, but in for example 5:th gear you will reach a high boost value first, then the boost level will follow the mentioned curve while increasing the rpm.

I checked the adresses you asked about and I had no notes at all. Try the Prograle forum.

/A

[arjunior45]

now is more clear. I do not have a clue about that function, sory.

Will do with prograle forum and see if something comes up.

Nick

[jimnielsen]

Attached is a picture of some data that I captured today re boost.

The red line is using values of 128 in the last row of the overboost duty cycle table. Boost is maintained at 1.1 bar to 7000 RPM.

The black line is using values of about 80 in the last row of the overboost dudty cycle table. Boost is maintained at .9 bar.

I also tried a run using values of 256 in the last row but this had no more effect (boost wise) than using 128.

I think that the air volume of the T3 turbo is maxed out at these values. I am going to get a T3/T4 turbo to try.

This small change to the overboost duty cycle table produced a 3 seconds per lap gain.


jimn~

[jimnielsen]

Any feedback on this? What I'd specifically like to know is has anybody been able to achieve more than 1.1 bar boost at 7000 RPM in 4th gear using the std turbo with ANY sort of boost controller - OR - is this the operating limit of the system?

Jimn~

[arjunior45]

sorry, can't say anything for more than 1.1 bar. The max I've heard of is 1.0-1.1 bar till the rev limits.

Nick

[#84]

1.1 bar at 7000 rpm is a lot. It is hard to say what the actual mass flow is, but according to attached file you only reach 25 lbs/min (11.3 kg/min) at that pressure ratio. In reality you will have pressure oss on the intake side (air filter) and in the output side (pipes, IC, throttle body) so maybe you may reach 28 lbs/min (12.7 kg/min) if total pressure ratio is 2.4. So yes, that is the maximum output of the turbo. I have nevere recorded more than 0.78 bar at 6500 rpm.

So, if I understand it correctly: You couldn't see any difference in boost pressure at any engine speed when duty cycle was set to 256 compared to when it was set to 128. Ok?

According to Fiat auto document the valve should be completely clsoed if duty cycle was set to less than 26 % and completely open if it was set to > 80 %. That means, with Jims information above in mind, that there is no more boost effect over 128*0,8 = 102.

/A

[jimnielsen]

#84 - do you have a copy of any of this 'fiat auto document' that you could post here or email to me?

Regards, Jimn~

[#84]

The attached document sholud be placed in some download area. It was (is?) available in the Italian Fiat Coupe club's website, but I didn't manage to see the website when I tried right now.

Note that the document describes the communication protocol via diagnosis port, not the coding for the internal ECU routines! Some conversions are the same, but not all. Tricky.

/A

[jimnielsen]

Thanks for posting the doc. I found that I did have a copy of it actually.

I would be good if there was a 'complete' explanation of the ecu coding - it must exist somewhere ?? :)


jimn~