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Author Topic: disable/raise max pressure exceeded limit (P1555 P0234) for part throttle w/ MBC  (Read 25451 times)
elRey
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How would you disable or raise the limit for max pressure exceeded.

I've increase requested torque. However, when using a MBC and not the N75 there are times during part throttle where actual boost will be higher than requested (requested is essentially 0 and actual ~5-8 in this condition) and that DTC is thrown and car goes into limp mode. It doesn't happen often (big turbo).

I would rather raise or tune it to still have the limitation, but have it handle the part throttle on a MBC better.

Thanks,
Rey
« Last Edit: May 18, 2015, 01:18:45 PM by nyet » Logged
Jason
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Breaks everything!


« Reply #1 on: November 25, 2010, 11:19:51 AM »

I think you are looking for KFDLULS

Edit:  To completely disable throttle cut, FF the whole table.  In the stock mbox file, I believe it allows for a 250mbar deviation at max load before throttle cut.  I also believe the max cell value is 1275mbar allowed deviation?  I had an OTS tune that worked great with an MBC, and KFDLULS was FF'd (1275 in each cell if you are using something like tunerpro).

I plan on first tuning with the N75, and then switching over to the MBC, unless I can find a way to keep the N75 100% closed until desired boost is achieved - from what I understand it only closes to 95%, so the boost ramp up is slower.  The response is awesome with just an MBC.
« Last Edit: November 25, 2010, 12:15:59 PM by Jason » Logged
hammersword
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« Reply #2 on: November 25, 2010, 12:20:03 PM »

yes, completely deactivation of the boost deviation will solve your problem

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elRey
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« Reply #3 on: November 25, 2010, 12:53:33 PM »

Is that sarcasm? I ask because you usually do not advise turning safety functions off. I'd rather not disable it if at all possible.
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Jason
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« Reply #4 on: November 25, 2010, 01:33:44 PM »

I don't think you need to disable it... log when you are experiencing throttle cut, then bump up the corresponding values in KFDLULS.  This is assuming you aren't exceeding the limits of the map sensor.
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elRey
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« Reply #5 on: November 25, 2010, 02:32:44 PM »

Unfortunately my ECU does not seem to have KFDLULS.
ME7.5 06A906032KR 0261207910 366816

I see DLUL and TULV1 which should be used with KFDLULS, but no KFDLULS.

If either of you don;t mind, was are the addresses for DLUL,TULV1, and KFDLULS if your files? Maybe it's there, but I don't have it marked. (I'm looking for relative positions. I know my addresses will not match yours)

Thanks,
Rey
« Last Edit: November 25, 2010, 02:35:52 PM by elRey » Logged
Jason
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« Reply #6 on: November 25, 2010, 02:37:16 PM »

KFDLULS:  0x19905   (8x8)
DLUL:  (don't have a definition for)
TULV1: 0x199A0
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elRey
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« Reply #7 on: November 25, 2010, 03:16:56 PM »

Thank you!

That puts it around 19A22 by relative offset to TUVL1, but nothing like that near there. The closest map I have that might be used is KLDLUL. It's an 8x1 map with what seems to be target boost pressure as input and maybe allowable pressure deviation as output.


-200.0   200.0   300.0   400.0   500.0   650.0   800.0   1000.0   hPa
_______________________________________________________
1000.0   410.00   360.00   325.00   305.00   300.00   300.00   300.00   hPa
« Last Edit: November 25, 2010, 03:19:00 PM by elRey » Logged
elRey
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« Reply #8 on: November 27, 2010, 09:51:42 PM »

KFDLULS:  0x19905   (8x8)

Thanks for all your help.
If I could ask for one more thing dealing with this map.... could you give me the factor/offest for the map values and both axis?

Thanks again.
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Jason
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« Reply #9 on: November 27, 2010, 10:32:37 PM »

After a closer look, I believe you are spot on...  It's allowable deviation by RPM and requested boost in hPa??

all are 8 bit values...

RPM (rows) 0x198F5
hPa (columns) 0x198FD
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elRey
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« Reply #10 on: December 06, 2010, 11:59:59 PM »

You would happen to have the offset and factor for thos axis, would you?

RPM and hPa for KFDLULS: 0x19905 (8x8) not KLDLUL (8x1)

Thanks,
Rey
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Jason
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« Reply #11 on: December 07, 2010, 08:36:23 AM »

Sorry, I'm such a spacebrain... my last post had the offsets but I forgot the factors...

These are for KFDLULS:

RPM (y) 0x198F5 * 40
hPa (x) 0x198FD * 10
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elRey
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« Reply #12 on: December 07, 2010, 12:08:34 PM »

You've been a great help. Thank you.
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elRey
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« Reply #13 on: December 07, 2010, 02:58:34 PM »

with your factors and 255 => 1275hPa = factor of 5, I get this:




Seems a bit more than your 250hPa allowable deviation.


With factors removed:



factors converted to psi:
« Last Edit: December 07, 2010, 03:06:28 PM by elRey » Logged
New2Tune
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« Reply #14 on: November 11, 2011, 12:33:45 PM »

Wanted to add that ELDOB the threshold for activating LDR might be of use in fixing problems like this if anyone else is having this issue.

Also another way to go about this without KFDLULS would be KFLDRX0 delta filling in overboost.  Reducing KFLDRX0 and raising your LDORXN would reduce the magnitude of the setback when you trigger overboost.  I believe setting delta filling to zeroes and raising max load during overboost to say 191 would effectively cut out the intervention completely.
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