I want to know if I can detect my engine is having hesitation/stumble problem from an OBD. I mean not from any fault codes, but from the parameters obtained from the OBD. e.g. calculate the obtained torque/power and compare with the power/torque demand (from OBD PID) and say if the engine is having hesitation/stumble
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How would you see power/torque from OBD? Stumbling and hesitation is usually felt by the driver, which is what makes him look for the problem.– I have no idea what I'm doingDec 7, 2015 at 12:48
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Power and torque can be calculated instantaneously (using OBD parameters) and Mode 1 - 61 gives the required value link– Soumya SenDec 7, 2015 at 13:40
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Are you wanting to know what parameters you should monitor in real time or are you expecting to be able to read something after the fact?– JPhi1618Dec 7, 2015 at 15:21
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@JPhi1618 Yes! I want to know the parameters I should monitor in real time and how will they vary.– Soumya SenDec 7, 2015 at 16:58
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Great, then you should be able to do this. Since hesitation is rarely seen as a fault (unless caused by misfires), ODB wouldn't store any data at the time. @Zaid's answer is a good start.– JPhi1618Dec 7, 2015 at 17:01
1 Answer
A stumbling engine should result in abnormal engine vibrations. It should be possible to use the knock sensor(s)/misfire counter to detect abnormalities.
Note that it will not be as straightforward as setting a simple threshold-based limit since the normal sensor readout will be heavily dependent on factors like engine speed.
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Thanks @Zaid . Can you tell me any possible way to do it? Any reference material? Dec 7, 2015 at 17:00
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@SoumyaSen I don't have any reference material, but I suspect that the usual signal processing techniques will be useful here - FFT, low-pass/high-pass frequency filters, online tracking of averages... You won't be able to simply code it up, some real-world testing would be necessary.– ZaidDec 7, 2015 at 17:10