Differences in F23a engines and ECUs

Hi everybody,

I am doing a manual conversion to a 98 Odyssey. It comes with a F23A7 engine with a OBD2B ecu. Because Odyssey's only came in manual, there is no manual odyssey ecu - so I have tried a 6th gen Accord ecu:
PAA-L11

However, using this ECU has resulted in a number of codes (as well as a loud ticking from the evap system when warm):
Error 9, 20, 22, 65 (and sometimes others)


The ECU layout looks the same, but the manual ecu has an extra chip. I am wondering why I would get all these codes with this ecu - So I am guessing there is significant differences in F23a engines and ECUs?

Can someone outline the differences?
I know there is PAA-L11 ecu, and PAA-L10 and even PAA-L00? Anyone know the differences?

Also what are the differences in F23a sensors between the difference engines.
Thanks!

Okay, so let me start by defining the codes...

9: P1381 9 Cylinder Position Sensor Intermittent Interruption
P1382 9 Cylinder Position Sensor No Signal

20: P1297 Electrical Load Detector Circuit Low Input
P1298 Electrical Load Detector Circuit High Input

22: P1257, P1258, P1259 VTEC System Malfunction

65: P0141 Secondary HO2S Heater Circuit Fault (Sensor 2)

If you were to try to plug in the Odyssey ECM right now, would any of these codes come up?

Let me address 22 since I have read the most about it. On our Accords that have been swapped, it is not plug and play to make the VTEC work. Some alterations are required. Take a look at this thread. http://www.6thgenaccord.com/forums/showthread.php?p=575130

Now, 65. Do you have a multimeter to check the resistance on the heater circuit? Maybe a connector got pulled on the downstream O2 sensor causing the heater circuit to be faulted. This could also be due to a blown fuse which I would check into.

Code 9. Typically attributed to the distributor as that is where the sensor is located. You'll need to verify its resistance. I think I read yellow and blue wires and 350-700 ohms.

Code 20, does the Odyssey even have an ELD? I really don't know. After some searching, it doesn't seem it does. You may have to do an ELD bypass.

Cool swap by the way!

EDIT: By the way, that EVAP tick seems to be what I call normal on 6th gen Accords. Not saying its right so much that I have noticed it on all 6th gens that idle when hot and it hasn't resulted in any codes so I haven't touched it due to the fact that EVAP leaks tend to be a pain to locate on these cars as RedRyder will happily tell you. Haha! Your Odyssey didn't do it before? Just wondering.

Thanks heaps for your reply James. Really appreciated.

james'99 said:

If you were to try to plug in the Odyssey ECM right now, would any of these codes come up?

Click to expand...

I haven't tried the odyssey's ECU with the manual transmission. Before the conversion there were no engine lights, but in saying this I have only driven the car for a short period (but everything ran alright except for the transmission).

Also, currently the ECU is with someone who is trying to modify it, so I unfortunately can not try it.

Let me address 22 since I have read the most about it. On our Accords that have been swapped, it is not plug and play to make the VTEC work. Some alterations are required. Take a look at this thread. LINK REMOVED

Click to expand...

Thanks for the link. Might come in handy when I wire the VSS. However, isnt code 17 VSS? Would a lack of VSS cause a 22 code? Note, that I have not driven the car with the manual transmission, only started it on jack stands. Also, see below image of the vtec solenoid- is it same as F23 in 6th gen?

Now, 65. Do you have a multimeter to check the resistance on the heater circuit? Maybe a connector got pulled on the downstream O2 sensor causing the heater circuit to be faulted. This could also be due to a blown fuse which I would check into. .

Click to expand...

I will be in possession of a multimeter soon. Regardless, it seems my car only has 1 o2 sensor before the cat (4 wire) - see below image. I see in the receipts that came with the car that a new cat was installed a few years back. Maybe the o2 sensor setup is different and causing this error???

Code 9. Typically attributed to the distributor as that is where the sensor is located. You'll need to verify its resistance. I think I read yellow and blue wires and 350-700 ohms.

Click to expand...

Does the distributor in the below pic look the same as the accords?

Code 20, does the Odyssey even have an ELD? I really don't know. After some searching, it doesn't seem it does. You may have to do an ELD bypass.

Click to expand...

See below image of engine bay fuse box. I do see what typically looks to be an ELD - but I am no expert. Why wouldn't the odyssey come with an ELD though?

Cool swap by the way!

Click to expand...

Thanks.

EDIT: By the way, that EVAP tick seems to be what I call normal on 6th gen Accords. Not saying its right so much that I have noticed it on all 6th gens that idle when hot and it hasn't resulted in any codes so I haven't touched it due to the fact that EVAP leaks tend to be a pain to locate on these cars as RedRyder will happily tell you. Haha! Your Odyssey didn't do it before? Just wondering.

Click to expand...

I do not recall the ticking before the conversion. I can hear it in car quite easily. Here is what I think may be causing the problem, but not sure [posted in a odyssey discussion without much luck]

"There is a chip missing in the Auto ecu compared to the Manual.. from my late night eyes the chip seems to be 10 pin. and connects to PIN 3 and 4 of the ecu plug.

According to online pin outs of obd2b:
PIN 3: 2WBS - EVAP Bypass Solenoid Valve
PIN 4:VSV - EVAP Control Canister Vent Shut Valve"


I have to be registered for 7 days before I can link to images. Could someone kindly link this in a post. (its the image I am referring to)
i58.tinypic.com/2czx6jl.jpg


Thanks again!

Not too much time to reply right now so this will be a little sloppy. I'm sorry about that. When I have time, I will clean it up.

VTEC Solenoid setup appears to be the same. What I will note is our oil pressure sensor is I think the OEM color of our VTEC oil pressure sensor is green and not brown. Lack of a VSS should result in a P0500 but in your case, code 17 as you stated. Does your speedo work at all?

Best thing you can do with the heater circuit is verify it with a multimeter when you get one. If it comes down to replacing it, I'd buy an Accord one for the F23A1 engine. For some reason, if you use the O2 sensor for an F23A4 on an A1, and vice versa, it rejects it and throws a code. I think it is a code 48 though.

I don't see an ELD here or in the parts diagram. Not sure why it doesn't have one to be honest but that said, an Odyssey alternator from Honda for this engine is about $1000 and the Accord one is $200 so maybe there is something different in the alternators.

Gonna try to do some more research on the EVAP tick. I don't know if I would personally mess with it if it doesn't have a code but will check into it.

Thanks again for the reply James. I think what we are discovering will come in handy for other members too (given there is a lot of incorrect information around on the 'JDM' F23a - which seems to be the engine in the odyssey).

1) Vtec pressure switch - Seems the odysseys F23a7 does not have one (see pic link below) - this is consistent with the information on the 'JDM' F23a. I guess I could put a 6th gen accord one in or just bypass it.
2) 2nd O2 - Seems there is no second o2 on the odyssey - this is consistent with the 'JDM' f23a. I guess I could install one and wire it to the ecu? Or possible bypass??
3) ELD - after doing some reading, it seems Australian CD Accords (and other models) do not come with ELDs. Maybe my odyssey doesnt have one either? I dont know if it would be possible to wire one up (or how the ECU controls the alternator)? I wonder if there is differences in the alternators too (pic below)?
4) Evap/intake- Other threads here have stated that there is a difference between the 6th gen accord F23a and the 'JDM' F23a - I would like to find out what they are [pic of intake manifold].
5) Cylinder Position Sensor - Who knows, maybe wiring to the ecu is different? Distributors different?


PIC: i57.tinypic.com/31688w9.jpg

Not a problem buddy! I'm surprised its not throwing more O2 codes since there just isn't a second one on the cat at all.

I also notice that the Upstream O2 is located way down the stream on this car. On ours, the first O2 is right on the bottom of the manifold. Using this ECU way be a mistake without swapping exhaust components considering the tune would be off based on the location of the sensor. I don't see why you couldn't bolt one right on. With that said, I'd consider finding some Accord components and doing some wiring. I think you may be better in the long run.

As for the ELD issue, you'll have to tweak it for yourself I think but...
http://www.stevemeadedesigns.com/board/topic/139844-how-to-eld-bypass-for-honda-civicaccordfit/

The manifolds are both different on the 'JDM' and USDM. Do you want pics of the US manifold?

The VTEC solenoid. I show a oil pressure sensor on this diagram, #12. Are you sure it isn't there?

A pic of the intake and exhaust manifolds on a 6th gen f23a would be good.
Sadly the image you linked to doesn't seem to work for me.


It seems my odyssey has a 4-2-1 manifold. Where as the 6th gen accord has a 4-1?
So i guess that explains why the odyssey has the upstream o2 a lot further back because that is where all the cylinders meet. In my mind, i do not see this upstream o2 sensor being much of an issue, because AFR is AFR right?

Thanks for the ELD link. I would have to apply it differently though, as the odyssey has no eld - i guess I would need to trick to ecu into thinking an ELD is there.


Pics of the manifolds, especially intake with the evap setup would be great.

Dxs said:

A pic of the intake and exhaust manifolds on a 6th gen f23a would be good.
Sadly the image you linked to doesn't seem to work for me.


It seems my odyssey has a 4-2-1 manifold. Where as the 6th gen accord has a 4-1?
So i guess that explains why the odyssey has the upstream o2 a lot further back because that is where all the cylinders meet. In my mind, i do not see this upstream o2 sensor being much of an issue, because AFR is AFR right?

Thanks for the ELD link. I would have to apply it differently though, as the odyssey has no eld - i guess I would need to trick to ecu into thinking an ELD is there.


Pics of the manifolds, especially intake with the evap setup would be great.

Click to expand...

I will take pic asap for you! Sorry that the pic I linked doesn't work for you. I will take care of that as well.

I assume you will have to apply that ELD bypass by wiring directly into the ECM. Unfortunately, I'm not doing it myself so you may have to pioneer and I will help where I can.

Is AFR just AFR? Kind of, but not really because it varies throughout the exhaust track Let me put it to you like this. At a constant speed, its kind of okay, but not really. When you accelerate, It really isn't okay. Think about the lag in the system. The car is constantly changing from rich to lean, rich to lean. The O2 sensors job is to tell the car what is happening based on that. Well, if the ECM is doing its timing based on the O2 sensor being located right on the manifold, when you move it all the way down stream like that, you are putting a lot of lag on the system without telling the computer you are doing so and performance will suffer and the car may run really rich or lean. Does that make sense? If you end up using an ECM where the O2 on the car is supposed to be located back that far, that's fine.

I understand what you are saying.
Say if the mixture is rich, so the ecu leans it, but because the o2 is so far back it is still detecting the rich mix because the leaner mix hasnt come to that point yet, so the ecu will still think it is rich and lean it even more..
i guess this depends on the sample rate of the sensor/ecu - or maybe the latency?
I wonder where you guys connect your o2 with aftermarket headers.


pics of the manifolds would be great too.

also, do you work on cars for a living james- done any tuning?

Computers by trade, cars by choice. The tuning knowledge I have is from working on my buddy's Subaru and by learning a little, you infer a lot more.

And yes, your logic is straight. I have a friend that has a header on his 2000 Accord that the O2 sensor sits just below where it normally does. On some of the headers, it relocates it down there now that I am looking into it. That is strange.

So you do have a header? Where is the OEM location on your car of the O2 sensor?