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Topic starter
Hi every one,
I have a '08 SAAB 93 TTID (Z19DTR).
When I use the standard PID for Intake MAP, the value displayed increase to 255 at his maximum value never above...
I read that it's a common issue with OBD II apps, but I don't know what to set in equation formula to get a accurate value for my MAP sensor.
I read in the WIS :
So I have to create a Custom PID with 010B, and set new equation...
But with which demultiplicator ?
Could you help me to understand?
(I'm really new in this world)
Thanks !
Posted : 03/01/2021 2:40 pm
Its likely you will need a custom pid
if your vehicle doesn't support 0170
or 0187 pids.
The scaling for 010B is fixed by standard
which apparently not used by your
vehicle (single byte resolution).
Posted : 03/01/2021 3:20 pm
Topic starter
Thank you Capp777.
It's not possible to use the standard PID 010B in custom PID and just change Scale or range?
If I use PID you say, what equation to use ?
Posted : 03/01/2021 4:29 pm
If the vehicle supports the other pids, a
quick web search should help with the
equations. I would think KOEO should
match atmospheric conditions...
I also believe the 010B pid wouldn't
handle the full voltage range needed.
But as always could be wrong.
Posted : 03/01/2021 6:30 pm
Topic starter
Thank you again, I'll try tomorrow, and get back to you. 😉
Posted : 03/01/2021 7:15 pm
i had the same issue like stated, no you cannot use the standard pid and change the value
the standard is 1=1 kpa if i remember correctly
some car will roll over ..256=1
some car will just stop at 255
you have to find another PID that will do the full range , if it exist
in the past i used an arduino to measure the voltage directly and send the data into the bus ...
but i finaly found the PID so got rid of the arduino
ps why 255 because the value is outputed in a 00 to FF format in HEX that as a maxium value of 255
Posted : 03/01/2021 7:41 pm
Topic starter
I've tried 0170 and 0187... No data sent back... :-/
Posted : 04/01/2021 11:04 pm
Hi,
have had similar "issue", following the datasheet of MAP sensor of my car is possible to read pressures from 27 to 400 KPA.
using this equation I can read pressures over 255 KPA:
A+256*(1-((24-A)&256)/256)
more details here: https://torque-bhp.com/forums/?wpforumaction=viewtopic&t=2894.0
Posted : 04/01/2021 11:17 pm
Topic starter
Hi Hiej,
Thank you for your help.
I had see your thread during my searchs before posting.
But your issues seems not really the same as mine.
Your pressure go on after 255, with 1 for 256, 2 for 257 and so on...
But in my case, it stop at 255 kpa.
So, I don't think that your formula could work for this problem.
Posted : 05/01/2021 9:54 am
a solution could be to find the PID that shows the Volts value of your MAP sensor (Hope it exist), then you can transform Volts to KPA applying a formula knowing that 4.65V = 300KPA and 0.40V = 20KPA.
Posted : 05/01/2021 1:10 pm
