Setting up a test bench

If you don't believe me, confirm yourself of the magical currents inside an L. All you need is:

In here I have the system connected. I've got the whole wiringloom out from the car, it really helps.

For a ignition system I used a selfmade driver and for a signal generator a CD-player (A genuine generator is on the never-ending shopping list). Just connect all the wires, get the spark going and let 'er rip! Don't measure the ignition coil primary voltage AND something else with the other probe, my scope leaked to the board and one ECU got toasted, cost $100 :(

This is what an Bosch Jetronic-L connector looks like, 1 is on the top left, 18 top right, 19 bottom left, 35 bottom right. Designations are:

No lambda here, it is only present on Motronic type ECU's.

You probably want to start by putting in a 100hz signal for 3000 rpm. Probe the end of R103 to get the transfer curve (use injection pulses for channel B trig.). Put a 470 ohms resistor in parallel with R103 and look what happens. Next, find the rev-limit and go just beyond it, then try probing at R106. Put the 470ohms in parallel with 106 and look what happens. Next you'd probably want to try to probe at the second (on the middle of board) custom board pins, choose 9th and 10th from the left. You should see a nice fig with the corrected airflow-sensor basic timing followed by the correction quantities (You will see that this condensator is used as a multiplier by the slopes) followed by the voltage correction time. Put a 47 ohms in parallel with R345 and take a look.

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