Use USDM or JDM ECU?

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Use USDM or JDM ECU?

Postby Nightfire » Tue Apr 01, 2008 12:13 pm

I got a JDM engine, radiator, tranny, ECU, wiring, Gauge cluster, and front axle/brake assembly from Jarco. I pulled the USDM wiring that goes to the ECU out because the JDM engine already has this attached to it, my question is would it be better to use the JDM ECU or the USDM ECU? Also, what else electrical if anything do I need to change? I know I need to extend the wires on some things to get them to the other side of the engine compartment.

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Postby WarTowels » Mon Apr 14, 2008 1:17 pm

The USDM and JDM Ecu are very similar with a few exceptions.

The JDM ecu is said to have a higher fuel cut, and higher boost maps - but it meant for higher octane fuel.

The JDM ecu also doesn't use any EGR. There may be some other minor differences, but I think those are the significant ones. There is more information to be had if you search.

There are a few different JDM ecu's, they are YEAR specific so you need to match the JDM ecu to either a JDM harness, or an alltrac harness of the corresponding year. Unless you want to repin it.

Hope that helps a little.

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Postby gt4rcdude » Mon Apr 14, 2008 1:50 pm

You'll have to use the USDM wire harness. The reason is the JDM one is made to go in the left side of the firewall. Provided you got the same year clip, you'll be able to use either ECU. I've been running the JDM ECU in my car over a year now. No problems with premium fuel.

The JDM does not have higher boost maps or cut. No EGR. When I used my USDM ECU I simply plugged in the EGR and set it off to the side, as the JDM motor didn't have mounting for it.
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Postby WarTowels » Mon Apr 14, 2008 2:08 pm

According to several members on the board the JDM ecu cuts above 14 PSI.

Isn't that higher than a USDM? I guess I just assumed it had higher boost maps, if it cuts higher.

It does however, have advanced timing and as I stated before no EGR, it is also supposedly limited to 180km (112mph).

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Postby gt4rcdude » Mon Apr 14, 2008 8:54 pm

WarTowels wrote:According to several members on the board the JDM ecu cuts above 14 PSI.

Isn't that higher than a USDM? I guess I just assumed it had higher boost maps, if it cuts higher.

It does however, have advanced timing and as I stated before no EGR, it is also supposedly limited to 180km (112mph).

-Towels


Mine cuts at around 14psi. And yes, it's speed limited but I don't think it'll work on a US car. The right hand drives use a an electronic pickup on the speedo adapter for the speedometer. USDM's use a cable. I haven't had it to 112 yet so I'm not sure. Unless it uses the same sensor for the cruise control.
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Postby Corey » Mon Apr 14, 2008 9:09 pm

Im not sure about fuel cut, as i dont have a gauge or controller. But ive also read about higher fuel cut. :shrug:

For top speed. I only have a 180 km/h speedo, but the needle went far past 180 to a logical 200 km/h speed cut, at around 5500 rpm last time i tried.

I do run 94 oct RON. it will run on lower.... but not happily. The difference between 92 and 94 oct is like 2 cents... big deal lol.
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Postby WarTowels » Fri Jun 20, 2008 2:31 pm

I'm going to test speed cut with JDM ecu on a USDM car... sometime soon.

I didn't realize it was 112, I was at 110... shoulda kept going.

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