OBD "Problem Cars"

Discussion related to external OBD sensors
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Harry
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Re: OBD "Problem Cars"

Postby Harry » Fri Mar 07, 2014 10:26 pm

Please follow the description here: viewtopic.php?f=20&t=1500

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Ray_S
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Re: OBD "Problem Cars"

Postby Ray_S » Sun Mar 30, 2014 3:18 pm

Any hint on which VE setting to start with a 996 turbo w/ around 1,3 bar boost to get fairly correct boost values on videos and logs? Anyone tried it and calibrated values already? I guess the default ,75 value will provide only a fraction of the actual pressure, right?

Using a BT1 btw.

Apart from that - thanks to Harry to include the calculated feature!!!


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Re: OBD "Problem Cars"

Postby Harry » Sun Mar 30, 2014 3:36 pm

MAP calculation depend on displacement, VE, intake air temperature, rpm, and MAF.
A little math... The reverse VE is going into the MAP result as a linear factor (as expected):

Code: Select all

calculated MAP = somefunction (displacement, intake air temperature, rpm, MAF)/VE

So if you read out the max MAP calculated with standard VE, you can calculate the VE correction factor:

Code: Select all

max MAP calculated = somefunction (displacement, intake air temperature, rpm, MAF)/0.75
1.3 = somefunction (displacement, intake air temperature, rpm, MAF)/(correction factor*0.75)

which in turn means

Code: Select all

correction factor = max MAP calculated/1.3

Never did that, but in theory that should give you a calibration.

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Re: OBD "Problem Cars"

Postby Harry » Sun Mar 30, 2014 3:37 pm

P.S. Please create a new topic when starting one ;-)


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Re: OBD "Problem Cars"

Postby ckowalc » Fri May 22, 2015 3:55 am

The first post says VSS must not be excluded but I tried it just to see what it would do and it seems everything is okay. A little bit faster refresh rate for the throttle and RPM when I exclude it. It seems like the GPS position (10Hz Qstarz) should be able to do the job of the VSS right? Any drawback to excluding it?

Also, is there a reason spark advance is not included? I doubt I'd use it much but I know it is available on my car from the Torque app.


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Re: OBD "Problem Cars"

Postby Harry » Fri May 22, 2015 6:23 am

This thread is quite old and things may have changed. Need to check the logs, but I believe I have added a fall back to GPS speed if wheel speed is not available a year ago... You will probably get not so smooth gear calculations with VSS disabled.

Besides this, there are tons of PIDs not read by LapTimer. Touch the Device Gadget in Engine View to see a list available for your car. Only those with an answering time added [50ms] are used. Each PID added slows down the rate. This is the reason only PIDs making sense for race analysis are added. For everything else, there are technically oriented OBD apps around.

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Re: OBD "Problem Cars"

Postby cobbyboy » Thu Jun 11, 2015 11:27 pm

This is probably more of an ODB problem, than a car problem. My BT1 seems to work fine with HLT, but it will not seat firmly in my Cayman GTS, making it wobbly to the touch and, I think, making it protrude too much. Anybody else had this problem with your car? Thanks.



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