Advanced Driver Assistance Interfaces, OBDII Final Year Project

Don’t try this – How to Overload OBDII

Posted on: November 12, 2009


After doing some more work with my prototype this week I decided to give it a try in my Ford Focus. I added the following features to the prototype,

  • Engine RPM
  • Engine Speed Mph
  • Battery Voltage
  • Fuel Level % (Not supported on my focus it seems)

Started the car and began the test, clicked connect, everything runs ok. Started the timer which polls for OBDII info every 100ms, Engine cut out!!!

Looked at my code and this is whats under the Timer event.

procedure TForm1.Timer1Timer(Sender: TObject);
begin
nrComm1.SendString(’01 0C’ + #13);
Memo1.Lines.Add(‘cmd 010C sent’ + #13);
nrComm1.SendString(’01 0D’ + #13);
Memo1.Lines.Add(‘cmd 01 0D sent’ + #13);
end;

By asking for 2 requests in 100ms AT THE SAME TIME, I was overloading the PCM and causing the engine to cut out. VERY BAD.

I now need to make changes for it to poll requests, at alternating times.

Here’s a screen shot of the new prototype.

OBDII Prototype

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