Thursday, November 24, 2011

Review: Davis CarChip Pro

This is a review of the Davis Industires CarChip Pro . 

The CarChip is a small device which plugs into your vehicle's OBD-II port, and acts as a datalogger.  It can record vehicle speed every second, and up to 4 other items at a slower rate of one sample every 5 seconds. Retail prices are around $80.

The device is simple to configure.  Once you install the software (which worked fine on Windows 7), and plug the CarChip in with a mini-USB cable (included), a step-by-step configuration walks you through the initial setup.

For example, you can choose to record 4 parameters at every 5s, from a choice of several standard OBD-II parameters, including engine speed, throttle position, engine coolant temp, engine load, air flow rate, spark timing, air/fuel ratio, battery voltage, and oxygen sensor voltage.  You can also set audible alarms, to have the device beep at you if you exceed a top speed, or a max accel/decel rate.

For my testing, I plugged it into my 2007 (which would be using CAN OBD-II), and drove a few trips.  I also induced two powertrain diagnostic faults: I loosened my fuel cap, and for a short time, disconnected my intake air temp sensor (IAT).

After removing the device and downloading the data to my PC, I was able to use the software to plot the recorded channels, and the device properly logged two DTCs, one for evaporative emissions (P0456) and one for the IAT circuit test failure (P0113).  By clicking on a menu choice, you can tell the CarChip to clear the codes next time you plug it into your vehicle.

Overall, I liked the CarChip, and I would recommended for several use cases.  A hobbyist or fleet owner who wants a low-cost way to log mileage, driving style, fuel economy, etc. would do well with a CarChip if they don't mind plugging into it every so often to download the data.  It could also be useful to someone who wanted to program it as a "trainer", to teach themselves (or their kids) not to accelerate too hard or brake too abruptly, to teach a high fuel economy driving style.

However, I wouldn't necessarily recommend this as a primary diagnosis tool, for example to debug DTCs or do performance tuning, because of its offline nature.  Someone who wanted to quickly determine why they have a Check Engine lamp, and perhaps check some of their engine control sensor values as part of the debug would be better off with an interactive scan tool.  Also, the relatively slow 5s sampling rate may cause users to miss some aspects of the engine performance, such as sudden lean fuel excursions or speed fluctuations.

My advice to Davis, to improve this product, would be to add a "live mode" which pulls the OBD data in real-time via the USB, and to add some sort of wireless interface so that the data can be monitored and downloaded via bluetooth without having to plug into the unit directly.

  • Simple to use software, easy setup
  • Ability to set speed/accel/decel alarms
  • Fault code logging and clearing
  • Small, unobtrusive
  • Data can be easily exported
  • Slow sampling rate (5s) on user-configured data channels
  • No apparent "live mode" to look at data interactively, while connected
  • No wireless transfer mode (bluetooth or wifi).
* Davis provided me with a sample unit, however I recieved no compensation for this review.

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