Hondata

We are dealing with 25-30 year old computers here, my man. Electrolytic capacitors have a finite life and when they go bad they can take out other components on the board. I'm not an electrical engineer, but other parts of the ECU may deteriorate over time as well. Not to mention the wiring in our cars that we plug the ECU up to is just as old. Some parts of the ECU can become damaged if shorted out, and that's a possibility dealing with old fragile wires which can have cracked insulation. Not saying that's the case with your car/ECU, but it's a possibility.

You were having this issue when your S200 was installed and now you're having the same issue with the S300. What's the common denominator? The ECU. You've probably got a component, trace, or something else messed up on your ECU that is only used when J1 is installed.

Dealing with these old computers, a backup ECU is the best/easiest/cheapest test platform you'll find.

Well some things would be good to know is

1) I sent back a S200 unit when I upgraded, was there anything wrong with this unit, was it tested?

2) The capacitors everyone keeps talking about replacing what to they control?
Is there a capacitor that fails that would cause the smptytons such as no spark when cranking but spark occurring in all the wrong key positions?

Spunkster or other admin have any information on this?

We always test the ECU to make sure it works on the test bench. We cannot remember specifics of every ECU that has ever come through the doors.

Bad capacitors can cause ay different issues, and they are well past their life expectancy.

My suggestion would be to try this ECU on a known workgin vehicle before doing anything further as that will rule out a great many things.

So if I provide the installed S300 board number (48732) for the upgrade Hondata cannot tell me if the old S200 I sent in was bad or not?

We cannot tell that at this time.