2.3 ULEV ECM interchangability ?
 

Hi guys i will be installing an 02 accord 2.3 ULEV auto into my 99 LEV 5sp, i think i will also need an ECU from an ULEV to make it runs right. So i want to know what ECU number are interchangeable ? Or any 2.3 ULEV will fit just fine ?

The part number for the PCM covering 98-02 ULEV LX/EX manual transmission accords is 37820-PAA-L23.

Your 99 ECU may work without any problems. I don't know if the ULEV uses different sensors or has tighter standards to set the check engine light.

I also don't know if the pinout for the 99 LX PCM is the same as the pinout for the 02 ULEV pcm.

So far i notice the new ULEV motor used a plug in the head where my motor used a metal sensor locates right on top of the transmission bell housing, it's a 1 pin connector looks like some kind of temp sensor http://imageshack.us/photo/my-images/840/20k14.jpg/ so i swapped it over. All other connectors just plugged right in. And looks like the LEV uses 37820-PAA-A51,A52,A53,to A54 all interchangable. And ULEV uses 37820-PAA-L23,L23,L95 and L75 might be interchangable, just not sure if the ECM on LEV is compatible with ULEV or not. I heard the ULEV uses a different (wide band)front O2 sensor than the one in the LEV, but i do have the front 02 sensor and exhaust manifold so if i have to i can take the header out and put the manifold back in there. I also have a complete engine wire harness for the motor which i could also swap it over to fit the new ECM if i have to, I'm also worry about the immobilizer system if i use a different ECM.

IIRC not only is the ECU very different, but the wiring harness had some substantial differences. I used to have a 1998 and the Helm book showed differences for the ULEV engine, but I don't have that book any more.

Front O2 sensor is a wideband sensor, and it's preheater comes from a different circuit (different fuse) that may not even exist on a non-ULEV car. That's one example that I remember, but there were several other things big enough to cause you grief.

You will have to decide if you want the ULEV setup or the "normal" LEV setup to properly pair with the PCM.

I just don't know what the significant differences are between those two engines.

If you have the whole wire harness for the engine and the main wire harness inside the car is compatible, I would consider going with the ULEV setup.

That don't sound good. So it sounds like almost imposible to go to ULEV motor set up from a LEV. I hate to pull the motor back out because it look so nice in my engine bay, and the junkyard said it would fit.

I believe the main difference is the exhaust manifold. Just swap the exhaust manifold from your previous engine on to the replacement engine and you should be good to go.

No need to swap ECU and then have to get ECU reprogrammed due to the immobilizer.

What exhaust manifold ? I'm running header, test pipe, no resonator hehe

The exhaust manifold is the cast iron piece that bolts to the cylinder head. It should have an o2 sensor bolted to it. It is #2 in the picture below.

http://www.hondapartsnow.com/diagram...old-456437.png

I'm not using the exhaust manifold because i'm using a header instead of manifold :-)
I'm reusing the old harness, ecu and O2 sensor, drove it for 20 miles and no check engine light on yet, idle is smooth. Hope this is all done for me right now.