Ok.. 96 is OBDII, although from what I understand some what broken, but never the less.. still OBDII
OK..
So I plan to update this car a weeee bit..
First things first OBDII to OBDI conversion..
Can some one please explain this to me?
I know I have extra sensors and such, but what does the conversion do.... I mean, If I put a P28 and a Hondata onto my car, does the ECU and hondata still look at the secondary O2 that OBDII has? Or does it just ignore it? What does it do with the extra crap thats on my car?

can any one explain this ????? so confused..




[Modified by Lildrgn Half EVIL, 1:01 PM 2/6/2003]

 

When you do a conversion from OBDII to OBDI, you are changing out the ecu also. Since the OBDI cars did not come with OBDII sensors, the OBDI ecu will not look for them.

In my case, I put a p28 ecu into my 98 civic EX. I was then able to get rid of the knock sensor and secondary O2 sensor.

 

as OBDI cars lack a secondary O2 sensor it is just ignored
so far as the conversion goes... http://www.c-speedracing.com/onlines...php?id=harness $200 for a conversion harness and then whatever ecu you might want and it's done. Or you can sit down and re-pin everything.

 

Yes, its all in the programming of the eprom chip.
For instance, a stock P28 ecu does NOT look for a knock sensor from the factory to begin with, Honda disabled it within the programming. Why? Because a SOHC VTEC engine doesn't make enough compression for the ecu to worry about knocking... at least that's what I've assumed. The funny thing is, Honda added and made the knock sensor enabled on all 96+/OBD2 SOHC engines.

But, when comparing 96-98/OBD2a & 99-00/OBD2b to OBD1 programs and ecu configuration, here's general breakdown of it:

- OBD2a/OBD2b is an 'upgrade' of OBD1. Honda added more sensors & changed a few things around which consist of these:

- ecu plug style changed a little bit between OBD2a (96-98) and OBD2b (99-00), and the major reason why is is because of the immobilizer addition made to 99-00/OBD2b ecu's.
- obd2a/b ecu internals are smaller (more compact chips with tiny-*** pins) and are harder to reprogram, that's why you don't see many places offering reprogramming for OBD2 ecu's, and why ecu jumpers for OBD1 conversions more readily available.
- added a 2nd 02
- relocated the AT sensor on some vehicles (except GSR i believe), usually located on the intake arm now, rather than on the intake manifold runner on pre '95 honda's.
- added a CKP (crank sensor) which is part of the oil pump.
- added an Immobilizer to the 99-00 ecu's, which conicides with the ignition system.
- Injector type changed to saturated (or pulse, forgot) as well as the plug type style.

Now, the JDM version of OBD2 ecu's have 'obd1' style programming, meaning they look for the same exact sensors as an OBD1 ecu, unlike the US version which looks for all of things I've listed above. One catch though, the JDM OBD2 DOHC VTEC ecu's do not look for a VTEC pressure switch (green plug on vtec solenoid). Honda....those funny unorthodox nutbags.


92-95/OBD1 ecu's have simpler programming in comparison to US OBD2 ecu's. The cool thing is that all OBD1 ecu's and some '89 but all '90-'91 ecu's both use a 28pin eprom chip, which is easy to reprogram if you have the hardware to do it. Blank OBD2 chips are way expensive as well in comparison to a 28-eprom chip.
OBD1 programming from the factory does not look for any of those additional sensors, Immobilizer, etc which I listed above for US OBD2 ecu's......only the knock sensor is enabled on all stock DOHC VTEC OBD1 ecu's and the AT sensor is always located on an intake runner, never the intake arm.


[Modified by Katman, 12:19 PM 2/6/2003]

 

thank you for the info.. that was very helpful...

another question for you..
my secondary O2... can I just cut that bitch off when I do the conversion?
right now it is just dangling out from underneath the car cause I have no CAT..

 

np.
yep, you can do whatever you want with the 2nd 02, I say just leave it dormant or take it out and put a plug in place of it....save the 02 as a spare part.

 

Yep.. you are the man...

Ok.. another question..
right now we have the secondary O2 just hanging, and we cut the wire on the harness that tells the computer to go look for problems so I dont get a CEL.. at this point can I remove the secondary O2 since its just hanging there, or should I actually wait for the ecu and hondata?

 

hrm, you don't have to cut it...you can just unplug it and be nice about it..heh.
As long as you have the Primary 02 sensor plugged in, you can delete the 2nd 02 sensor.

 

i know what im doing this weekend..

OFF WITH THE SENSOR!

thanks again Katman, I will probably have more questions later.. you have been more than helpful .

 

np.
just hit me up on IM.

 

don't mean to jump in with a noob question but i can't resist...so when doing a swap in my 00 CX, would it be smart to stick with the OBD2b? the OBD1 ecus seem like they would be more versitile...is this true? i am looking into a swap right now and trying to do some research. this thread was extremely helpful.

 

OBD1 is the way to go if you can't afford higher end ecu tuning like an AEM EMS, hondata, etc. I totally suggest going OBD1 since it's more forgiving on many levels of tuning & powering an engine.

 

thanks...most likely the way i will go...just wanted an expert opinion

 

np.

 

ALL OF THIS WIRING SHOULD BE CORRECT, IF ITS NOT LET ME KNOW. THIS IS A GOOD THING TO SAVE OR PRINT OUT FOR FUTURE REFERENCES.

92-95----------------------------96-98
OBD1 ecu pin # - connect to - obd2 ecu pin # WIRE

A1-----------INJ1-------------------------A4
A2-----------INJ4-------------------------A1
A3-----------INJ2-------------------------A3
A4-----------VTS-------------------------A8
A5-----------INJ3-------------------------A2
A6-----------HTCNTL---------------------A6
A7-----------FLR1-------------------------A16
A8-----------FLR2-------------------------A16
A9-----------EACV------------------------A12
A10----------------------------------------NONE
A11----------------------------------------NONE
A12----------FANC------------------------A27
A13----------WARN-----------------------A18
A14----------------------------------------NONE
A15-----------ACC------------------------A17
A16-----------ACGC----------------------A19
A17----------------------------------------AUTOMATIC CRAP
A18----------------------------------------NONE
A19----------------------------------------AUTOMATIC CRAP
A20-----------PGS------------------------A15
A21-----------IGP1-----------------------A20
A22-----------IGP2-----------------------A20
A23-----------PG1------------------------A10
A24-----------PG2------------------------A23
A25-----------IGP1-----------------------A11
A26-----------LG1------------------------A9

B1------------IGP2-----------------------A24
B2------------LG2------------------------A22
B3----------------------------------------AUTOMATIC CRAP
B4----------------------------------------AUTOMATIC CRAP
B5------------ACS-----------------------C5
B6----------------------------------------NONE
B7------------CL\NPSW-----------------C29
B8------------PSW----------------------C16
B9------------STS-----------------------C6
B10-----------VSP----------------------C18
B11-----------CYLP---------------------C4
B12-----------CYLM---------------------C14
B13-----------TDCP---------------------C3
B14-----------TDCM---------------------C13
B15-----------CRNKP--------------------C2
B16-----------CRNKM--------------------C12

D1-------------VBU--------------------C10
D2-------------BKSW--------------------D5
D3--------------------------------------NONE
D4-------------SCS--------------------C7
D5--------------------------------------NONE
D6-------------VTM--------------------C15
D7-------------TXD\RXD--------------------C8
D8--------------------------------------NONE
D9-------------ACGF--------------------C17
D10------------EL--------------------D16
D11------------TH--------------------D1
D12-------------------------------------NONE
D13------------TW--------------------D2
D14------------O2--------------------D7
D15------------TA--------------------D8
D16-------------------------------------NONE
D17-------------PB-------------------D3
D18-------------SIL\SLU-------------------A30
D19-------------VCC1-------------------D4
D20-------------VCC2-------------------D10
D21-------------SG1-------------------D12
D22-------------SG2-------------------D11