F23A1 to H23A swap throwing Cel

[lithiumus]

F23A1 to H23A VTEC swap throwing Cel P0400

I went to check out the progress of the swap. The engine is in and looks good. My mechanic started it up and it's running fine but when we took it for a ride, it threw a cel code and started flashing.

We kept the original OBD II wire harness and ran my F23A1 OEM ECU. Will the P5P work with the H23A or will I need a JDM ECU. My mechanic tells me that a JDM ECU won't work due to the EGR sensor being 2 wire for JDM and 3 wire for USDM. What is the best way to wire a JDM ECU with a USDM harness?

 

[lithiumus]

I got the car back from the shop with a commitment that they'll do what's necessary to get the car running 100%.

My F23A1 OBD II ECU is still on the car and throwing a random misfire on all cylinders. My mechanic told me that it's due to a missing crank sensor on the JDM engines...

The engine shop provided a P5M ECU from a 97-01 JDM Prelude but it was an OBD IIA connector and my F23A1 ECU is an OBD IIB connector. The shop swapped the P5M for a PCT which has an OBD IIB connector but it is from an ITR.

Will this work or should I be insisting on a P5P which is a JDM H22A Type S ECU? I'm going to try the PCT ECU on the weekend and report back... maybe someone can learn from this or shed some light.

 

[d112crzy]

is the h23 obd2?

get an obd2 to obd1 conversion, then use a regular h23 prelude ecu(p14).

its most likely throwing codes becuase if the h23 is obd1, then the obd2 ecu is looking for a shitload of other sensors that are not there.

look on Rywire - Online Store for obd2-obd1 convserion harness.

 

[lithiumus]

Thanks d112crzy. Yes the H23A is an OBD II engine from a 00-01 JDM Accord SiR. The F23A1 ECU threw 5 codes, Random Misfire and a Cylinder Misfire for each cylinder.

I just tried the ITR PCT ECU and it doesn't start. My mechanic indicated that I may not have large enough injectors for the ITR ECU to work properly. Looks like I'll need to find a JDM H22A ECU with OBD IIB (1999+) connector...

 

[d112crzy]

it will not run right at all with the h22 ecu. it will throw even more codes.

save yourself tons of troubles and just convert to obd1 and use a p14/p39 or chipped p06.

 

[lithiumus]

Hey d112crzy, you were right. We tried at least 5 different ECU from the original H23A Auto ECU, F20B, P75, etc, etc and none of them would start. I was told that the JDM Idle Control Valve being 2 wire rather than 3 wire... but I'm suprised that the USDM ECU controling 3 wires seems to work and none of the JDM OBDII B ECUs worked.

They suggested the same as you and that I go to OBD I. They got a chipped P30 and put in H22A maps with increased fuel. They didn't have a P72 but will a P30 be ok esp. losing the IAB functionality?

 

[d112crzy]

i never knew those were chippable and tuneable(at least not with crome or uberdata).

what is being used to tune?

but if they can chip it, then they can add IAB's, its only a few wires and resistors.

 

[lithiumus]

They were using Chrome Pro to program it.

So where do the wires need to go? They gave me an OBD II B to OBD I harness for the P30 ECU. So you can add the IAB functionality to the P30? I don't mind doing the work, point me to where I can find reference material and I'll figure it out. Thanks for letting me know!

From your perspective, will only changing the throttle body to an OBD I H22A work?

 

[d112crzy]

it should work if you wire it all correctly.


but this is a link on how to add IABs to a p28. Im not too sure how similar the boards are to the jdm p30 since i have never worked on a p30.
PGMFI.ORG - Grassroots ECU Development - Library . AddIABToP28

 

[lithiumus]

Wanted to say Thanks and I appreciate all the help you've provided! I'm dropping off the car today and getting it back tomorrow. I'll report back how things go and share any info I can.

 

[lithiumus]

Further updates...

After a long discussion with my mechanic, I've decided to stay OBDII. It's my daily driver and the fact that I can't pass emissions if I convert to OBDI is not appealing and would rather retain full functionality of this engine.

The H23A VTEC uses a 3 wire IACV and the newer 6 wire ECU controlled EGR valve. If I go OBD I the EGR will not work unless I convert the EGR to the old vacuum style as well.

My mechanic indicated that the only H22 engines (aside from my JDM H23A) that used 3 wire IACV and the new 6 wire EGR would be the last H22 generation Euro Accords. I know the ECU type is PDE but I'm still confirming the version code that supports the EGR.

The original H23A ECU did not work as it was an auto tranny and expected the 4th OBDII connector to be functional. Not sure what the differences are but it would not start.

Looks like my options are...

1. Find a PDE Euro Accord ECU with the EGR functionality
2. Purchase an AEM EMS and tune it for both performance and emissions

 

[lithiumus]

Update... I found a PDE OBD2B ECU from a Euro Accord Type R and I'm waiting for it to arrive.

The codes that the ECU is throwing are Cyl Misfire 1 through 4 plus a Random Misfire code. It's the same all the time and if I drive it like a granny, the car does not throw a code, but on the highway even cruising or going up a steep hill, usually causes it.

My only hurddle once I get the ECU will be the Immobilizer. Several options...

1. if the Immobilizer is the same as the Doctronic supported one, I'll get a doctronic to bypass it.

2. I've got a contact with a Honda tech who may be able to reprogram the new ECU for me or convince my dealer who I repeatedly reported oil burning which eventually ended up with 90% compression loss in cyl 2 and an engine swap to do it.

3. I can try to remove the Immobilizer module from the PAA accord ECU and install it in the PDE. Obviously, if the modules are different, I won't be able to do that.

 

[lithiumus]

The ECU arrived. Unfortunately the Immobilizer is not the same as the Doctronic one.

My contact at Acura is confident that the HIM / HDS Honda system will be able to erase and reprogram the ECU. I'll be trying it out on Tues morning...

 

[lithiumus]

I plugged in the ECU today to test it out. The immobilizer definitely works. As soon as I plugged it in, the green key kept flashing and would not start.

The one alarming thing is that it threw a new cel code!

P0400

It's an EGR Flow Malfunction code. It's not in the Accord Service manual nor is it in the Prelude service manual. When I use my scan tool to clear it, it comes back in about 2-3 seconds. I was sure that the EGR would be fine but something is obviously wrong. I plug my OEM ECU bad in and it works fine.

I'm taking the car into Honda to have the ECU reprogrammed but the P0400 code concerns me...

 

[lithiumus]

Looks like you need the original VIN to be able to reprogram an ECU. The HDS hooked up fine but to do anything, it looks like you need the VIN that is programmed in the ECU...

Beginning my search for an AEM now...

 

[lithiumus]

Futher update... there was a communication error between the ECU and the Immobilizer transponder, regardless of the VIN. I understand that ANY Accord Type R VIN will work and may not be a factor.

After much research on European parts vs. North American parts, it looks like the immobilizer inside the PDE ECU and the immobilizer transponder for the Accord Type R is different than my immobilizer transponder.

My 2 options are to source a transponder unit from Europe ~$50 US value and try to reprogram the ECU again or to pull out my OEM Accord ECU and see if the immobilizer boards are similar enough and desolder / swap the 2.

I don't really want to mess around with the circuit boards esp. if the immobilizer boards don't work and end up damaging the ECU...

 

[lithiumus]

I pulled out my PAA OEM Accord ECU and the Immobilizers are almost identical. I think I'll give it a shot and try swapping them...

 

[lithiumus]

Success! Alsmost... I desoldered and swapped the immobilizer chips last night and the car started like a charm with the new PDE ECU. The old cylinder misfire and random misfire codes are all gone.

But as I suspected, the new P0400 EGR Flow Malfunction is there and comes back when you clear it. There is also a new phenomenon where after 5-10 seconds upon starting the car, I hear a mechanical ticking sound from the engine @ about 2.5 ticks/second. It does not increase or decrease in speed with RPM change.

Not sure if I mentioned this but when I was running the old PAA ECU, the car would produce a high pitched squeal when trying to accellerate moderately or hard and seem to produce little power. I always thought that it was due to the ECU, but it seams that this still occurs with the new ECU so it must be something mechanical...

Need to have my mechanic look at it again. Any ideas?

 

[hondarin]

Maybe you should try taking the EGR off and cleaning it out.

 

[lithiumus]

Thanks Hondarin, I'm going to do that the next opportunity I get to do some maintenance on the car. i.e. Oil change, spark plugs, distributor, etc.

I decided to plug my Scan tool in to see what is going on. I noticed that the Primary O2 sensor was pegged at 1.275v and the Secondary O2 seemed to work fine. The Primary O2 sensor rarely dipped down while the Secondary was very active (as it should be) while driving.

I got a hold of a Euro Type R Service Manual and spent some time mapping out all the ECU OBD2b pinouts and discovered that 4 wires require remapping that includes Primary O2 sensor heater control, EVAP Purge valve, Power steering and MCS.

I also discovered that 7 wires / functions are not supported on the Euro Type R but exist on the 99 Accord. The only ones that concern me are the EVAP bypass and EVAP canister valve control but they only need Batt signal so that's easy to solve, it's the Electric Load (EL) and ALTC signals that the Euro Type R alternator does not require but it seems the H23A may need it. I believe that to be the knocking sound...

Since this discovery, I needed to swap back to my old PAA ECU and since I soldered my IMMO chip to the PDE ECU, I figured it was best to install a single row socket so I can pull my IMMO chip and plug it into either ECU as needed.

I'll post some pics when I have a chance.