Dear donatas,

I think if you need to ANALYSE the sparksignal you'll need another controller.
Try thinking a DSP, cause when it comes to SPEEDY AD and ANALYSING the 8051 cannot do the trick.

Take a high speed AD and sample into SPEEDY RAM. Then send the signal to a PC to analyse and display the data.

For the SPARK voltage. There are standard HIGH-VOLTAGE probes available for any SCOPE.

TRY searching under TV-accessoires in your local electronic-shop. They are SAFE and SOLID and saves you the trouble for designing these KILLING schematics.

Bert Sesam.

PS. : Have in mind that you CANNOT EXTEND nor ADD wires to the HIGHVOLTAGE SPARK cable. This will change the IGNITION behavor!