ECU change needed upon changing engine?

[s2kjn]

Hi All,

I have found a SUPER low mileage 2002 engine which I'm seriously commiting to buy, which was imported from Japan to fit into my 1999 model. Can I use my current ECU or will I need to buy the ECU harness from them too?

Also, I was quoted $7k for ECU + Harness, gearbox, diff and driveshafts. What do u think? and NO im not telling u were Im getting it from as I have dibs on it ;)

[AusS2000]

You can use your ECU.

[s2kjn]

Even though its from Japan? So it being tuned in Japan and all that wouldn't matter? The main reason why I'm getting this is so I can build an FI thats quicker than yours LOL. That being said, I would obviously be getting and am ECU anyway, so does this query even matter?

[AusS2000]

The JDM engine is slightly higher compression (to take advantage of their higher octane fuel). If you use a JDM engine make sure you only buy the highest octane fuel you can get.

As to ECU's probably best to use the AU ECU. It will have less advanced ignition and probably not as lean. But either will do in most conditions.

BUT, the JDM engine is not the ideal basis for FI. You want a lower compression for FI, not higher.

[s2kjn]

Darn....Hmmm

[AusS2000]

No biggy though. Although many these days believe the stock AU engine and compression is OK for FI and long as you tune for it and limit the boost, for really big boost you need to lower the compression.

The proper way to do this is with low compression pistons. The quicker/less expensive method is with a thicker headgasket. It has it's downsides but it's working for me. And if you're replacing the headgasket it doesn't matter what engine you start with.

[s2kjn]

So...say if I were to get the JDM engine, and decide to go FI with it, what you're saying is that:

1.) Replace to a thicker headgasket
2.) Tune

Which is what I would have to do with an AU engine anyway? Not that in one way doubt your bountiful knowledge Aus, but do you know of anyone or of someone who is in the same/similar position as I that has done this?

Surely someone on this forum has a JDM engine in their N/A / FI. Care to share out there?

[ALPS]

why don't you put the new motor into your car, and then work on the au engine. rebuilt it from scratch and replace everything that is needed to have a good build, rather than take risks and do it with temporary fixes and always stress about it.

And if you ever blow it because of wrong tuning, hey atleast you've got your super low mileage jap engine ready to be put back in. I'd rather risk blowing my old motor than my new one. Hey but i've never built a motor before or had a car which has had a built motor, so i wouldn't know. it's just a thought. lol

[s2kjn]

Because that would defeat the purpose of me getting the new engine. I'm getting the engine for under 3k, so pulling out my old rebuilding it and then putting it back in will cost me much more than double that.