RPM display lags

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mdknutsen
Posts: 4
Joined: Mon Feb 04, 2019 12:17 am

RPM display lags

Post by mdknutsen »

I'm running RCP mk3 and a Samsung Tab 8 device connected by bluetooth. RPM is coming from an obd2 connection to my 2006 Mitsubishi evo. RPM displays but the response to changes is rather slow. I'm currently running that channel at 500 mhz.

Any ideas on how to improve the channel response?

brentp
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Post by brentp »

Hi,

Are you using the legacy OBDII adapter, or do you have the CAN bus adapter for reading RPM? Also, how many other OBDII channels do you have enabled?
Brent Picasso
CEO and Founder, Autosport Labs
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mdknutsen
Posts: 4
Joined: Mon Feb 04, 2019 12:17 am

Post by mdknutsen »

Just saw this reply...

I'm using the legacy adapter. I've just recently removed all other channels to help focus on RPM. This improved the feed; however, it's still having issues where the feed will freeze. This only occurs when the car is moving.

brentp
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Post by brentp »

Thanks. The older protocols (pre-CAN bus) are notoriously slow, and were never really intended for data logging like this - and this is a limitation of the ECU - RaceCapture queries the data as fast as the ECU will allow.

Some of the legacy OBDII protocols are especially slow, like the ones that implement the ISO9141 protocol. What year/make/model is the car?

Also, note that the sample rate you set is the rate which RaceCapture reports the current value - that's a rate independent of what the ECU can provide.

RaceCapture has a fairly advanced OBDII query scheduler that will optimize the queries based on the sample rate set. You'll want to set the sample rate of, say, RPM higher than a sensor that changes slowly, like Engine Temp.

This blog post is very useful, we highly encourage reading it. https://www.autosportlabs.com/racecaptu ... -released/

If you're using a RaceCapture/Pro, you might be able to tap a wire into the ignition system directly using an RPM/Timer input channel and the RPM response rate will be incredible. You can measure RPM this way, and then use OBDII for the slower channels. You have quite a bit of flexibility in this case.
Brent Picasso
CEO and Founder, Autosport Labs
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mdknutsen
Posts: 4
Joined: Mon Feb 04, 2019 12:17 am

Post by mdknutsen »

The car is 2006 Mitsubishi Evo. I'm pretty its a limitation of the ECU OBD2. I saw improvement when I reduced the number of channels, just not while the car is moving.

Trying to tap into my ignition was going to be the next attempt. Either way this is just a hold-over until I upgrade to a standalone ECU.

Thanks

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