Hey guys,

Well it looks like if I don't find the problem on my motor soon, I'll be getting a new/used motor. I would like a JDM motor (higher compression), OBD1, closed deck. What do I need to know/get in order to get it to work in my 5th gen? I know that I'll need a conversion harness from the OBD2 to OBD1 ECU. But some questions I have is;

- Do I have to worry about the OBD1 distributor?
- Don't JDM ECUs have a speed governor? If so, what is the bypass for it?
- The power steering on the 4th is different from the 5th gen... can I just use my 5th PS components?
- Are the TPS and MAP sensors different from the 5th gens as I've seen on some 4th gen Preludes?

Any input or experience would be greatly appreciated.

Keith

 

OK first off, you need a helms manual .. the injectors, resister box, and distributor are all different

if you wanted to goto odb1, the odb2 harness is different so an odb1 ecu wouldnt work (i could be out to lunch on this) ..

my advice, get ajdm engine, and use all your sensors to keep it odb2 .. its cheapest and easiest

 

you could leave it OBD 2 and pull parts off the existing engine, assuming of course that the OBD 2 parts you would need are not causing your current problems. Hardest part would probably be swapping the oil pump to get the crank sensor, but I bet you could look into the wiring and use the OBD 1 distributor sensor and modify the OBD2 wiring harness. I think most all the other sensors are the same, and most other parts are pretty interchangeable except injectors and if you have atts you will have problems trying to put that onto a non-atts JDM block. Good luck.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flyrod &raquo;</TD></TR><TR><TD CLASS="quote">you could leave it OBD 2 and pull parts off the existing engine, assuming of course that the OBD 2 parts you would need are not causing your current problems. Hardest part would probably be swapping the oil pump to get the crank sensor, but I bet you could look into the wiring and use the OBD 1 distributor sensor and modify the OBD2 wiring harness. I think most all the other sensors are the same, and most other parts are pretty interchangeable except injectors and if you have atts you will have problems trying to put that onto a non-atts JDM block. Good luck.</TD></TR></TABLE>

That's what I was going to suggest.

I believe only the power steering brackets are different. Anyone else know for sure??

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by AndyD &raquo;</TD></TR><TR><TD CLASS="quote">

That's what I was going to suggest.

I believe only the power steering brackets are different. Anyone else know for sure??</TD></TR></TABLE>

Yeah, it's different for sure.. but I think all my 5th gen stuff will bolt up just fine.

Keith

 

Swap your 5th gen distributor, external ignition coil, alternator, and fuel injectors onto the JDM engine. This will allow you to use your current 5th gen engine wire harness. This applies if you get a JDM OBD1 engine.

If you get an OBD2 style JDM H22A, you shouldn't have to swap out the fuel injectors or alternator, only the distributor. Some JDM H22A engines use an internal coil distributor. USDM H22As use external coils. They can be converted but for ease of installation just use your 5th gen distributor and external coil with your stock engine wire harness.

As stated before, the only problem is the lack of a crankshaft fluctuation sensor on the oil pump that OBD2 ECUs require. Since you are converting to OBD1, it doesn't matter though.

Don't use any of those generic 'chipped' ECUs. With all the mods you have, you need to have your car tuned with something like Hondata.

 

For the powersteering components, swap your 5th gen stuff on the JDM H22A. All the mounting holes on the engine are the same but the mounting brackets vary depending on what vehicle and year the JDM engine came out of (Prelude or Accord).

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boomslang &raquo;</TD></TR><TR><TD CLASS="quote">Swap your 5th gen distributor, external ignition coil, alternator, and fuel injectors onto the JDM engine. This will allow you to use your current 5th gen engine wire harness. This applies if you get a JDM OBD1 engine.

If you get an OBD2 style JDM H22A, you shouldn't have to swap out the fuel injectors or alternator, only the distributor. Some JDM H22A engines use an internal coil distributor. USDM H22As use external coils. They can be converted but for ease of installation just use your 5th gen distributor and external coil with your stock engine wire harness.

As stated before, the only problem is the lack of a crankshaft fluctuation sensor on the oil pump that OBD2 ECUs require. Since you are converting to OBD1, it doesn't matter though.

Don't use any of those generic 'chipped' ECUs. With all the mods you have, you need to have your car tuned with something like Hondata. </TD></TR></TABLE>

Thanks Rustin.... I'm getting a JDM H22A OBD1 motor. Do I swap the 5th gen distributor, external ignition coil, alternator, and fuel injectors onto the JDM engine still? I thought the 4th gen injectors are larger. I will be using a JDM OBD1 P13 s well.

Thanks for your help!!!

Keith

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Keith &raquo;</TD></TR><TR><TD CLASS="quote">

Thanks Rustin.... I'm getting a JDM H22A OBD1 motor. Do I swap the 5th gen distributor, external ignition coil, alternator, and fuel injectors onto the JDM engine still? I thought the 4th gen injectors are larger. I will be using a JDM OBD1 P13 s well.

Thanks for your help!!!

Keith</TD></TR></TABLE>

Yes, use your 5th gen external coil, alternator, and distributor.

If you are using a stock JDM P13, then use the JDM injectors. The size is different from 5th gens. You will have to wire in the injector resistor box from a Honda (4G Prelude/Accord/CRX) because the OBD1 Prelude injectors are low impedence.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by boomslang &raquo;</TD></TR><TR><TD CLASS="quote">

Yes, use your 5th gen external coil, alternator, and distributor.

If you are using a stock JDM P13, then use the JDM injectors. The size is different from 5th gens. You will have to wire in the injector resistor box from a Honda (4G Prelude/Accord/CRX) because the OBD1 Prelude injectors are low impedence.</TD></TR></TABLE>


resistor box? Where is that located? Thanks Rustin..

Keith

 

It's mounted on the driver's side near the firewall. It's about the size and look of a PC CPU heatsink. It's bare aluminum.

 

Is it part #1?



Think I can easily find this used?

Keith

 

Yes, #1.

 

Gotcha... more parts I have to buy...

So basically, the 5th gen distributor, external ignition coil, and alternator are all plug n' play? No solding and rewiring needed? (well, except the injectors).

Thanks Rustin... you've been a great help.

Keith

 

Yes, it'll all be plug 'n' play except for the injectors.

You'll have to wire in the resistor box and OBD1 style injector clips. The injector clips should come with your longblock.