Timing & Insulators AT vs MT

[nakedandfam0us]

Putting a 2002 ej251 out of an impreza m/t into a 2000 outback a/t. 

 

Why, oh why, is the timing different between an auto and manual? I have a fsm for a 2000 legacy.

 

FSM:

Ignition timing [bTDC/rpm]:

MT vehicle: 10°±8°/650

AT vehicle: 15°±8°/700

 

Also, I was planning to swap the injectors between the two. Looking at the FSM it shows just an o-ring seal for the a/t, an o-ring and insulator for the m/t. Anybody know what that's all about?

 

Thanks! The build is coming along slowly but quite nice. 

[Fairtax4me]

You don't need to worry about it ignition timing because the ECU will set that on its own. There is no way to adjust it so just roll with it.

 

Don't bother with swapping injectors, waste of time. The flow rates are almost exactly the same and the ECU will just adjust pulse width to adjust how much fuel it needs.

[nakedandfam0us]

thanks for the reply but that didn't answer any of my questions lol. I'm curious as to why the injectors are insulated. I couldn't come up with a good reason. 

[Fairtax4me]

Not real sure what part you're asking about.

Several reasons for insulation, these days it mostly for sound.

On some of the older injectors they had problems with the tips freezing in cold weather and causing hard/no starting. Possibly the reason there, but I don't see why the transmission would matter for that.

 

 

Ignition timing is probably different because of emissions. The auto trans puts more load on the engine it idle, so engine speed needs to be higher to compensate. Bumping up the timing advance helps increase engine power at low RPM without largely increasing fuel consumption.