How do ecu differ in operation
 

I am having an odd issue with my car, it kept going into limp mode but manage to get it out but when I drive along the first turbo is boosting perfectly and everything works however after the switchover I have no boost at all.

Now when i plugged in a borrowed apexi both turbo's boosted perfectly and had no transition problems. Had the commander plugged in and could see nothing that could be causing it to go into limp mode. The tps was off slightly but have had that adjusted.

Now I put back in the original ecu and have the same symptons as before. I reckon the ecu may be damaged or faulty so have sourced another stock ecu for a couple of quid. Now I am wondering if this replacement stock ecu will actually just work the same as the old one and that my car will run on an aftermarket ecu.

Apart from being adjustable and removes limp mode how else would the apexi function differently from stock? would it control the boost better than the stock ecu?

You need to specify the year of the car for starters followed by what ECU identification numbers you are using.

I was meaning in a general sense, my stock ecu was a n3a7 for a manual 95 jdm. Fitted the corresponding apexi ecu and car behaved completely differently so I am curious whether my ecu was bust or if the apexi one can just run the car and it's turbos better on a base map.

ok So you are having issues with the Apexi , but the car drives fine with the Stock ECU ?

other way round. drives crap under stock ecu but fine with apexi so wanting to know whether I should buy another stock ecu.

have you tried to pull codes from the stock computer? the stock ECU has a number of things that can cause a limp home, and the apexi does not. so you may have something wrong, that the stock ecu cares about and the apexi doesn't.

can't pull codes on jdm cars as they don't have an engine warming light. I got a replacement stock ecu and it seems to be working now, both turbo's are boosting and the car started first time so hopefully my original ecu was just broken

you can plug a light into the diagnostic port, and it'll spit out codes