F23A1 to F23A4 in 00 Accord

[FoolishOne]

Hey guys, I just posted this on H-T and they said they this would be a better place to post it.

Okay so a while ago I helped my buddy swap a F23A4 into his 00 Accord which had the F23A1. We kept the A1 harness and ECU, ever since it fired the first time there was a CEL light which was P0135. I looked into it and is a malfunction in the o2 circuit. We have replaced the o2 with both the A1 and A4 o2 and the code still doesn't go away. After switching o2's I cleared the code with code reader.

So my question is, is there a differences in the two harness? or anyone know how to start diagnosis the code?

 

[CG6Lemon]

need the ulev(a4) harness and ecu.

 

[jeffpanya]

wouldnt you need diff o2 sensors too ?

 

[FoolishOne]

well I just went over the wiring diagram for the ulev and non-ulev and it looks like there is a very small difference in the harness. I'm going to poke around and see if I can mod the A1 harness to eliminate the code.

 

[FunnyVictor86]

Primary o2 is different, Secondary o2 should be the same, Ecu is different, and the Engine Harness like said should be slightly different. Let us know what happens.

 

[FoolishOne]

I'm curious if there is a service manual online I can DL somewhere? I got the wiring diagrams from the sticky but it doesn't give me voltage specs.

 

[FoolishOne]

Okay looked at the wiring and I would have to do more then a little hacking to get it to work. So I have an idea that might work? So basically the o2 is sending/receiving the wrong signal to the other sensors. (I think?) But my idea is to basically switch the ULEV sensors that are connected to the o2 back to the F23A1 sensors.

In the A1 some of the wires are traced to the Engine Coolant Temp., Air Intake Temp., and TPS. Where as on the A4, the sensors just mentioned are controlled by the ECU.

Is there a way that you guys and look up part numbers? I would like to see if they are different.

Here is the wiring diagram for both engines.
This is the F23A4

and here is the F23A1

 

[talontsiawd]

I don't really know much about this but i believe that the ULEV has a wideband O2 which is what is probably giving you problems.

 

[FunnyVictor86]

Don't quote me but i think that the dizzy might be different too.

 

[redlinevtec]

Don't quote me but i think that the dizzy might be different too.

lol sorry I had to quote you.

The EGR valve, rear O2 sensor and the distributor are the same part numbers as a regular F23A1. The front uses a wideband 02 sensor and the ECU is different than a LEV A1 ECU. But you can use a ULEV engine in a regular F23A1 engine, just swap everything over from the A1. The only thing that is different is the Exhaust Manifold and cover. Just use your A1. Now if you were going A4 to A1 that would be a different story. If you don't have the right set up, you will smell raw gas coming out of your exhaust. For instance, a wideband O2 sensor on a LEV VTEC ECU will throw a code and not burn fuel correctly because the LEV ECU is not programmed to use a wideband O2 sensor. You need the ULEV ECU if your going to run ULEV O2 sensors. But you don't need any of those components. The A4 is practically the same engine as a A1. It just has a hideous valve cover. Been there, done that. Either something wasn't plugged in correctly or your not getting enough continuity. Check your wiring and don't start messing with your harness. Trust me it's a nightmare. Check the continuity of your front O2 sensor harness. Hope this helped.

Oh, I almost forgot. The catalytic converter is also different on the A4. The part number for the ULEV is 18160-PAA-L20 and the A1 is 18160-PAA-305. The A4 cat is about $800 online while the A1 is $500. These are online discount OEM prices. So yeah. Use your existing set up.