I looked at my ecu because it has no revlimit and is modifyed so vtec kicksin at 5200 to see what kind I would need for replacement, and it is a pr4 and im pretty sure that is for the ls motor and I want to get the stock ecu,do I just buy the pr4 or do I get a pr3?
Ryan
Here’s a list of Stock ECU’s and how to identify them
http://pgmfi.org/resources/FAQ/identification.html
Chunk
why do i have a pr4 on the my car then im so lost, maybe its totally custom?
Ryan
if you have b16 with a pr4 ecu your car will run like it was an ls motor. your vtec wont kick in but dont rev it over 6700 rpm. i had this same set up and drive my car for a month and half till the ecu went out on me and went to limp mode. best suggestion is to get a p28 and put a hondata. also if your running a pr4 you will be needing to convert your dizzy to obd1 (if you dont have it yet) and jumper harness. make sure you look for a shop that can install the chip, dyno, and tune in one facility so you save more.
my vtec kicks in at 5200 so yea obviously it works, cani just plug the pr3 ecu in?
Ryan
no. if your pr4 is controlling vtec using an extra output it most likely wont be the same pin that a stock pr3 uses for vtec. a pr4 also doesnt use any vtec sensors, it uses 1 wire vtec control. chances are to use a pr3 you will need to hook your vtec solonoid up to the correct ecu pin then add wiring for knock sensor and vtec oil pres sensor.
why would you want a pr3 if your motor is running good with the pr4?
because the whole no rev limit thing bugs me tons.
Ryan
you could just get a chip from a member on here with a rev limit - I think Xenocron writes them, ask him maybe.
i dont think xeno will even burn a chip for someone unless he is tuning your car. my advice to you is pickup an msd 6al box if you are obd0 or pickup the crane “ignition upgrade” kit if you are obd1. msd uses pills to limit your rpm which is a pain, crane uses a digital rev limiter, change your redline with the spin of a tiny knob thing.
I just want the stock ecu, this is getting on my nerves I think it disables my o2 sesnor to so i get bad gas mileage, I just want to return to stock or sum kind of stock ecu, what will it take?
Ryan
i’m running an obd1 pr4 ecu in my teg… i’m running a b18c1 block with b17a head…
i have modified the non vtec pr4 ecu to vtec… if you know what you’re doing or have someone do it for you, its not impossible.
ryan15, do you have a vtec controller? like vafc?
if you can get a high resolution pic of the inside of your pr4, i can tell you exactly whats going on…
i have 2, modified obd1 pr4 ecus running vtec… one is in my teg, other is in my EG race hatch with GSR motor and ITBs 
(i did all my own mods to the ecus)
also if your ecu is chipped i can help you out with a chip that will get u better gas milage and have a reasonable rev limit… and any other option you might want on the chip.
What are you using to engage VTEC? And how did you rig up Knock sensor and VTEC Oil Pressure? Did you jsut bypass those and not use them at all? And are you jsut running 1 O2 then? sry for the questions.
if you take a look at a p28 ecu (D series vtec ecu) there is no knock sensor board in it… some of the JDM B series like the JDM P30 ecu doesnt have knock sensor board either…
the chip (ROM as we refer to it) controls everything… if the hardware is there it’ll work… so i added the components to the ecu for vtec operation… the rom does the rest…
the ecu itself is pretty universal, as long as it has all the components for different options like vtec. its up to the rom to actually use the components
if you look at a p28/p30 ecu and a obd1 pr4 ecu, they are very similar (cept for the jdm p30 cuz most of its components are surface mount)
the pr4 will be missing the components for vtec… also if you have an auto ecu you’ll have more components for the auto tranny lockup solenoid… so in reality… a p28 with auto tranny will have a completely “populated” circuit board honda would leave off the components for vtec and auto tranny on the manual pr4 ecu… if you know which jumpers to use to enable a circuit on the pcb (printed circuit board) and the correct components, the pr4 obd1 ecu can be converted to auto and vtec
also the wiring harness is missing the wires for vtec soleniod and pressure switch… ecu will read them if they’re present… so just a matter of either getting a vtec wiring harness or adding the pins to the plus and running the wires yourself.
obd1 honda/acuras use only 1 o2 sensor
and about the knock sensor, most hybrid motors (read lsvtec/crvtec) dont use knock sensor… not to mention that above 4500 rpm, the knock sensor isnt used cuz it cant tell the difference from engine noise to actual knock.
its all up to the tuner to make sure that your motor doesnt knock
my ecu doesnt have knock sensor, and if it did, it would throw the KS code since i’m not running a KS on my poor mans ITR. and thats why chipped p28 ecu’s are so popluar cuz they dont have Knock sensor on board
heres the ecu i’m running in my race hatch with gsr and itbs its an obd1 ecu from 92 LS integra
Wth, you added a whole new peice to the circuit board hehe
that extra circuit board is for real time programming, it plugs in the socket where a normal eprom would be.
when i’m not tuning i pull it out and put a jumper on the wiring that u see there so it runs normal with a regular eprom.
just get a pw0 and wire vtec like you just did the swap yourself. easiest way to do it. stock and a good ecu. im sure you could get a few $$$ on ebay for it.
ryan15, what year is the car?
He should get a PR4 instead so that he doesn’t have that lame 180KM/H governor
he has one. why do you need to go over 180 km/h? you speed demon.