Can anyone tell me what the difference is between the PR4 and P75 ECU. I have a 92 Integra RS which came stock with the PR4 ECU. I got a performance chip which was a P75 which doesn't run well with the car. I get some detenation (at least that what it feels like) around 3-4K RPM and it just doesn't have the power like the stock chip does. I have tried several different types of the P75 chip including a stock map with a 8000 rpm rev limit and I still got the same results. Why am I having these problems and what might be the fix

 

maybe you got an OBD2 p75

 

If he got an OBD2 P75 it wouldn't even plug in to his harness. As far as your problem, you say you feel like you get detonation...can you hear it detonating, or the car just sputters? Do you have a known good OEM ECU that you can substitute in? The PR4 and P75 ECUs should be the same, as is the P74.

 

With the OEM chip the car actually runs its best. The only problem is that with the upgrades I have done (i.e., cam, pistons, etc.) the rev limit is to low and I am missing out on some high end power. The P75 chips I got would take it to 8000 rpm, but the problem came along with it. As far as the detonation, I'm only guesssing as I have only read about what detonation is. It almost fells as if one of the cylinders doesn't fire but its not constant. It is random. My other guess is that the mapping for the P75 chip has different timing setpoints than what the PR4 does. You say they are the same but why did Honda label them differently if they are the same. There has to be differences. Any other ideas?

 

1. throw whatever chip it is you have down the drain
2. get something programmable and tune it