This ECU JDM? 37820-p13-j00 555 JMT 3J0 - Honda Prelude Forum

ScottH23 · 05-17-2003, 12:54 PM

I'm guessing yea cuz of all the j's but it's same size as USDM and I've heard some or all JDM ecu's are smaller. Also, is it true that JDM ECU's are 32bit as opposed to 16bit?

37820-p13-j00
555 jmt
3j0

4bidden · 05-17-2003, 02:47 PM

Those J's do not mean its JDM. Come to think of it, I dont think there is a way to verify its JDM without pluggin it in and taking it to speed limiter.

shiftgearz · 05-17-2003, 05:50 PM

Could be JDM:

37820-P13-XXX

Not 100% sure...

4bidden · 05-17-2003, 05:56 PM

37820 is for all Honda ECUs I'm pretty sure, we had P13s in the US, and the last 3 digits are for revisions and to tell if its auto/manual so I dont know how to tell if its USDM or JDM?

Fast&furiuslude · 05-17-2003, 05:58 PM

my speed limitor sucks

it was like 122

4bidden · 05-17-2003, 06:08 PM

Why do you need to go past 122 anyways? lol

concLude · 05-17-2003, 06:21 PM

is there a difference in the fuel curves or timeing on the jdm p13 compared to the usdm p13? or is the only difference the speed limiter?

4bidden · 05-17-2003, 06:22 PM

People say the fuel curves and timing is different but I doubt anyone can prove it.

Zimmlude · 05-17-2003, 07:36 PM

There is a way to check JDM vs. USDM by opening the ECU up. The ambient pressure sensors are different between the two. I know someone selling those "spoon" chips on e-bay had a way to identify them but I am not sure if they are still up.

4bidden · 05-17-2003, 08:24 PM

Aha!!!!

ScottH23 · 05-17-2003, 08:55 PM

thanks, it's a jdm p13 with the extra connector for 4 wheel steering but it works without 4 wheel steering connected. No CEL's either but if Japan uses 100 oatane fuel i'd be willing to bet a lot it has diff fuel maps.

Absolut · 05-17-2003, 10:22 PM

Ok, a few things to get straight.

1st:
Japan uses a different method of testing for octane.

Quote:

The pump octane is also referred to as the Anti-Knock Index (AKI). AKI is determined based on an average of the Research Octane Number (RON) and the Motor Octane Number (MON). The formula is RON+MON/2 normally abbreviated as R+M/2 on the pump.

The MON is a measure of the gasoline's ability to resist knock under sever operating conditions. MON affects high speed, part throttle and performance (under load such as in passing). The RON on the other hand, is a measure of gasoline's ability to resist knock under less severe conditions. RON affects low to medium speed knock and engine run-on (dieseling). For a given AKI, RON is typically 8-10 points higher than the MON. As an example, 87 AKI (pump octane) fuel would have a MON of 82 and a RON of 92.

Japan only uses the RON method, giving higher results. Its the same octane rating, just a different number.

2nd:
The 4WS has NOTHING to do with the ECU. The 4WS has its own computer in the trunk, there are no wires that connect the two.
If you have an ECU from Japan with an extra connector, to the best of my knowledge, you have an ECU with Traction Control.

That is the 4WS computer in my trunk.

Thats my JDM ECU (its says 2W on the side , not shown)

3rd:
Ofcourse the JDM engine is going to be faster, it has a .6 higher CR and the fuel and ignition maps to back it up. Japan doesnt have the same emmisions testing as the US, they most likely run a little phatter over there. I get about 19mpg city and 26 hwy at the most with my JDM H22 and JDM ECU.

Not trying to flame anybody, but reading post after post of wild speculation is like being over an H-T.com

EDIT: CR mistake. see below.

4bidden · 05-17-2003, 10:31 PM

Wild speculation, where did that come from?

Your facts are wrong also....the difference in CR is .6, not .2.

Better double check next time before you start calling us HT'rs.

Absolut · 05-17-2003, 11:19 PM

Quote:

Originally posted by 4bidden
Wild speculation, where did that come from?

Your facts are wrong also....the difference in CR is .6, not .2.

Better double check next time before you start calling us HT'rs.

Freaking Typo! (.2 would not make much of a diff anyway) My bad.

The speculation about the extra connector, maybe it wasnt wild, but speculation none the less.

ScottH23 · 05-18-2003, 06:25 PM

1. I said "if" japan uses 100 octane..... thanks for clearing that up anyway though

2. The pic 4bidden posted said "JDM P13 /4W STEERING" under the JDM ecu and the "4W" on the sticker of on my ECU would hint at 4 wheel steering even if it's not what it's there for

3. Dunno why you said any of this beings no one contradicted it in the thread.

Absolut · 05-18-2003, 07:10 PM

Quote:

Originally posted by ScottH23
2. The pic 4bidden posted said "JDM P13 /4W STEERING" under the JDM ecu and the "4W" on the sticker of on my ECU would hint at 4 wheel steering even if it's not what it's there for.

The orignal ECU from my Si motor said 2W on the side.