It's a factory sensor in the gearbox, but there is more than one. There is also two ECU's, one for the engine, one for the gearbox, that I am replacing, as the engine has been replaced with something more powerful, and now changes gear too soon.

I haven't been able to work out interrupts yet, do I have to use the CCP1 pin? I haven't used interrupts at all, is there a "dummy's guide" anywhere? haha

I programmed it today to read with PULSIN. I am reading the tacho, and the speedo now with PULSIN, but the reults are average. There is some 'contact bounce' with the speed sensor, that gives me erratic readings. I have programmed it to take two readings, and only use them if they are similar which is working. But with the PULSIN_MAX @ 10000, reading the RPM, and the SPEEDO, and sometimes having to re-read the speedo, the whole program runs fairly slow until the car speed, and the RPM increase. I would still like to get the capture interrupts working.

Also, I have run out of program space. It's a project that has grown over time, and now it handles the auto gearbox, monitors engine specs, and does climate control. Also has a setup menu where sensors can be calibrated, and gearbox and air-con settings can be changed. Current pic is a 16F877A.

From what I can tell, the 18F452 is pin compatible, and has twice the program space. Would it be viable for me to port my code over to the 18F452? I have only used 16F devices before.

Thanks...