OBD0/OBD1 year of production clear up!

cm90si · Post by **cm90si** » Fri Mar 14, 2003 3:44 pm

There is some misunderstanding in the Honda tuner world on OBD0/OBD1 years of production.

In 90-91 fuel injected Honda Preludes were produced with B20A/B21A motors that were predecessors to the current popular B-series and H-series. As I understand Hondata system will run on a 4-cylinder Honda with OBD1 harness. From the research I have determined that OBD1 Preludes were made starting in 1990 model year. I have a 1990 Honda Prelude (B21A) Si that IS OBD1. But a lot of reputable Honda tuners are trying to prove me wrong by stating that my car is OBD0.

This Helm's manual scan of 88 Prelude Si troubleshooting guide http://www.honda.co.uk/owner/PreludeMan ... /6-139.pdf shows that in 88-89 Preludes were indeed produced with an OBD0 system, but in 90-91 Honda rewired the Preludes to OBD1 system according to this 90 Prelude Si ECU scans in this link http://www.honda.co.uk/owner/PreludeMan ... /6-117.pdf

90-91 Preludes use PK3 ECU with has identical harness plugs as a P74/P75 92-95 Integra LS/GS ECU.

Question for Hondata researchers:

Can we conclude from the above data that Hondata system will also work on 1990-1991 fuel injected Preludes if the factory ECU is swapped out with P74/P75 like it works for 92-95 Preludes

cm90si · Post by **cm90si** » Mon Mar 17, 2003 8:42 pm

I just plugged in a P75 ECU into my 1990 Prelude Si and started the car. It purrs like a kitty. No trouble codes or any malfunction.

Post by **Hondata** » Mon Mar 17, 2003 10:16 pm

What I think you have is like the 91 Integra ECU - an OBD0 ECU with OBD1 plugs. Look inside the ECU and tell us what processor is has - it should be 66301, 66207 or 66991

cm90si · Post by **cm90si** » Fri Mar 28, 2003 7:58 pm

on the inside of the B21A1 ECU, there is only one chip that begins with
66...
It is the largest chip on the board so it may be the processor. Anyway,
the number is none that you listed. It is M66911.

ahnold · Post by **ahnold** » Wed Jul 30, 2003 8:42 pm

so what's the verdict on this? I also have a 1990 prelude si and am interested in hondata.

cm90si · Post by **cm90si** » Thu Jul 31, 2003 8:49 am

ahnold wrote:so what's the verdict on this? I also have a 1990 prelude si and am interested in hondata.

You can run Hondata chipped P74/P75 Integra LS ECU in B21A1 Preludes.

ahnold · Post by **ahnold** » Thu Jul 31, 2003 12:19 pm

you have done this? If so, does it pass emissions? are there any problems, or wiring modifications?

cm90si · Post by **cm90si** » Thu Jul 31, 2003 4:02 pm

ahnold wrote:you have done this? If so, does it pass emissions? are there any problems, or wiring modifications?

Like I said, I ran a stock P75 (Integra GS) ECU on my B21A1 without any problems or rewiring. Hondata should do the same as it goes off of stock wiring and sensors.

I have no clue on emissions, I don't have any in my state.

FuzzyGreen · Post by **FuzzyGreen** » Thu Sep 18, 2003 10:14 am

Correction. Only cars equiped with the B21a1 engine in 90-91 were equiped with OBD-1 ecus. I have a PR4(92 integra ecu) with S200B running just fine at the moment.

nitroice40 · Post by **nitroice40** » Sat Sep 20, 2003 7:09 am

I have a 91 pr4 integra, would a p74 or a p75 ecu work in my car. I have clear plugs on my dis.

Whats the diff between the 74 and the 75

thanks

cm90si · Post by **cm90si** » Wed Apr 07, 2004 5:27 pm

nitroice40 wrote:I have a 91 pr4 integra, would a p74 or a p75 ecu work in my car. I have clear plugs on my dis.

Whats the diff between the 74 and the 75

thanks

P74 is an OBDI Integra LS (94-95)
P75 is an OBDI Integra GS (94-95)

Hondata

OBD0/OBD1 year of production clear up!

OBD0/OBD1 year of production clear up!

1990 OBD1

Re: 1990 OBD1

1990 prelude

Re: 1990 prelude

b21a1

Re: b21a1