what do you mean unchipped? i would assume you mean a chip to take off the rev limiter and speed limiter
asuming you build up motor internals it can let you rev higher than the factory ecu, if you havent prepared your motor for the higher revs, it also gives you a chance to destroy your motor very easily.
speed limiter, no real cons asuming you know not to go 130 on city streets, just disables fuel cut.
the air/fuel map will also be different if it is supposed to be for a different motor, i will leave it to someone else to answer that end of it, as im not to sure of the differences there.
actually, an unchipped P28 is just a 92-95 civic ex ecu, which is sohc vtec... i actually had to run with this horrible ecu on my B16 for a day to pass smog (was actually the 96-98 ex ecu, pretty much the same but OBDII, long story) the cons are, the fuel mapping is all wrong for it, vtec kicks in too early, and the revlimit hits at like 7,000?? something like that, but it is not very fun. it will run the motor, but i dont reccomend it. i now have a skunk2 chipped P28, which works nice little rich, but i've fixed that with a vafc.
Sorry if I sound uneducated (because I am when it comes to swaps) but I would like to learn. I have the chance to get a p28 but as I understand it was not made for my engine. The donor car that my engine came from was in a bad accident and the ecu was crushed. I was wondering if the p28 would even work or would I need to get it chipped to work with my engine. This is what I was told and I just wanted some other feedback. Thanks for your help!
Yeah I want to learn, especially because I got a good deal on my b16 and don't want to screw it up because I'm "uneducated". Every reply is appreciated. I figure this the best place to learn, I beleive I can learn alot more from you guys than I could learn in a book or manual. Thanks again.