evo8

hey,
i know what an obd is...im just confused on what the differences are in each.

thanks in advance!!
-MiKE

Estorvito

I just found this info....Hope It Helps.....................
FIrst things first.....
OBD stands for On Board Diagnostics. Pre-OBD ECUs are ECUs made prior to the first OBD standard, OBDI, which was released in 1992. The easiest way to tell what generation of ECU you have (OBD0/1/2/2.5) is to look at the connectors. . OBD0 connectors have fewer pins.

-"OBD0" is generally used (in honda-speak at least) to refer to 88-91 ECUs based on the Oki 8XC154-8051ish MCUs. The PR3 and PW0 are oddballs here, as they have OBD1ish brains with OBD0 electronics. Likewise, "pre-OBD" is generally used to refer to any pre-92 ECU but particularly ones not using the 8XC154 chips. OBD0 ECUs "blink" when the CEL (Check Engine Light) is lit to reveal the code that the ECU is throwing. Most OBD0 ECUs use internal program memory but the 90-91 PM6, PM7 and PR4 all seem to consistently use external ROMs for program memory, making program modification trivial.

-OBD1 is the first true standard. I don't know what they specified exactly. OBD1 Honda ECUs are a significant advance over OBD0 ECUs. Looking at circuit boards, it is obvious that there are fewer components, cleaner designs, etc. These ECUs use the Oki 66K series MCUs. Most use the onboard A/D conversion facilities provided by these chips. Most OBD1 ECUs use internal program memory by default, but space for external ROMs is silkscreened onto the circuit boards and can be enabled by adding several components along with a ROM chip.

-OBD2 ECUs are used in 96-00 hondas. They are based on the 665XX series MCUs, and are EXTREMELY integrated. OBDII offers a much more sophisticated interface for diagnostics and datalogging. OBDII adds a significant number of sensors. Little is known publicly known about reprogramming OBDII ECUs, although a company named TechTom make a wide variety of products for OBDII ECUs. OBD2.5 is a newer revision of OBDII. Little is known about it. Many people with OBDII cars choose to convert to OBDI electronics in order to use a hondata or other aftermarket ECU that has features missing from the stock ECUs.

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LBR=LowBudgetRacing
My civic build thread

civicious

OBD0 or Non-OBD: Pre-92. Sucks for tuning, but you can buy Ebay chips for it. Has 2 1-wire O2 sensors that are essential for VTEC.

OBD1: 92-95. Best for tuning, compatible with Hondata, Uberdata, etc...has one 4-wire o2 sensor and is DEFINITELY the best for tuning.

OBD2A: 96-98. You can't chip it or anything, but I think you can have it reprogrammed. Has 2 4-wire o2 sensors.

OBD2B: 99-01. Worst of all. Same O2 sensor setup as OBD2A.

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CMRA #265
http://www.myspace.com/civicious
AIM: greyfades

evo8

thats is so much great info!! thanks for all the help

i have a 95 civic ex by the way. so its OBD1 and im planning on boosting my stock d16 after a compression test and leak test.

so my car is perfect(easiest) for tuning?? and if i deside to swap out my motor for a b series, i need to make sure that is it between 92-95 to keep is OBD1??

thanks for all the help!!!!