PRA vs PRB ECU Differences

Hondata model coverage & ECU application questions.
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R23AOU
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Joined: Sat Jan 13, 2018 2:30 pm

PRA vs PRB ECU Differences

Post by R23AOU » Sat Jan 13, 2018 3:13 pm

To try and cut a long story short, I'm in the closing stages of building a brand new Lotus Elise S1, the only items left over from the original car will be the front and rear clams, and the boot floor. Other than that, 100% new (bar a reconditioned Honda K20A2 engine upgrade).

The engine I have installed is a UK EP3 Civic engine, a PRA ECU with K100, narrowband O2, and stock engine loom.

In error I have purchased and installed a Rywire race chassis loom for US PRB ECU engines

https://www.rywire.com/product-p/k-sub-race.htm

thinking it would keep things simple and look neater than butchering a Civic loom and having relays etc. dotted about. I did note the comment about using an RSX Primary O2 sensor, but didn't pay it too much attention.

From what I can see from snippets of information, people say there aren't many differences between the PRA and PRB ECUs, mainly the O2 sensor wiring. Does this mean that if I rewire the Rywire's O2 wiring to PRA configuration, all will be fine?

Have fired it up many times as it is, so obviously the fueling / power / engine crank must all work. The engine revs, rev counter works. I do get a MIL light come on, but guess this is the O2 sensor issue.

Have a KPro4 PRA ECU ready to fit so I can read my own fault codes and do any investigation prior to taking for a dyno session, but don't fancy cooking that if there are significant issues with my current setup.

Any PRA ECU based information much appreciated!!!
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Spunkster
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Re: PRA vs PRB ECU Differences

Post by Spunkster » Mon Jan 15, 2018 11:03 am

The PRA ECU can only run a narrowband sensor. The PRB can run a factory wideband sensor.

R23AOU
Posts: 2
Joined: Sat Jan 13, 2018 2:30 pm

Re: PRA vs PRB ECU Differences

Post by R23AOU » Mon Jan 15, 2018 1:42 pm

Spunkster, thanks for the reply.

From what I can gather from looking at pinouts I have found for the PRA and PRB ECUs, all I need to do is take the wire out of Pin 16 on my "A Connector" and terminate it into Pin 4 of my "E Connector". Once I get my pins through the post I'll give this a go. If it doesn't flag an engine fault with my K100 ECU, I'll plug my KPro one in and see what faults are present and take it from there.

Hopefully this will work. When I read that the Rywire chassis harness was for an RSX/EP3, and needed an 02-04 RSX Primary O2 sensor, I just assumed it was a different connector and that was about it.

All else fails I can butcher a UK EP3 chassis loom from eBay, just wont look as neat in the end.

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