Why does everyone use a p28 to do their tuning on. What makes it superior to an oem ecu?

 

It is an OEM ecu. And has high availability.

 

A p28 is an oem ecu.

Please review Information :: EFI Beginner Guide for more information on this subject.

 

As others have said a P28 is an OEM ECU. It gets socketed depending on which type of EMS you are going to run. The P28 doesn't have any advantage other than already having the VTEC components installed. You can do this to NON-VTEC ECUs such as the P06. The P06 is essentially the P28's little brother. I wouldn't say the P28 is extremely abundant, but it definitely is way more available than say a P30 or P72 ECU.

So with all that being said, depending on your needs it may be that you don't need VTEC or other features of other ECUs like a knock board. In my opinion the P28 is definitely not a superior platform as it has no knock board capabilities. It's just cheaper and more readily available than other superior OEM ECU options. Also, people usually call a VTEC converted P06 a P28 anyways, so take it with a grain of salt.

 

I guess I misexplained myself. What I wanted to know is, why people don't use the ecu that came with their car, instead of buying a separate ecu.

 

You are asking a very broad question, as it depends on which ECU came in your car. If you have OBD-0, then it's an upgrade as OBD-0 tuning is very limited and outdated. If you are OBD-1 then you are good to go with what you have. If you have OBD-2 then you essentially have to downgrade to a OBD-1 ECU due to no tuning support for 96-00 / 01 Honda / Acura ECUs. So there are situations where you must switch ECUs and other situations you can use what you have. No matter what, you must still chip the ECU you are going to use to be able to use an EMS.

The flipside is some people want to have their stock ECU as a backup in case stuff goes wrong with the modified one. As in for potential future troubleshooting or even the sale of the car.