I have a 1973 1.7 L. The idle gets under 1000 rpm and wants to turn off. I had a bad auxiliary air regulator and replaced it with a 2.0 L one (I was told that it would work with mine). Is the problem the AAR or something else?

Thanks,

A bad AAR valve would make your car idle higher when warm.

Idling under 1000 rpm when warm is normal.

You say it wants to turn off. Does it turn off?

Have you try adjusting your idle screw? After I replaced some vacuum hoses, I had to turn mine up a little.

All Djet aar's are the same. 1000 rpms is normal. Did you mean 100? Idle should be adjusted warm.

The car turns off cause the idle gets too low. I tried adjusting the idle screw, but it doesn't change the idle at all.

timing or idle richness on ecu will effect low idle too . is the idle screw all the way out?

If the idle screw does nothing, sounds like a vacume leak to me

The Idle screw is all the way out, but it doesn't change the idle at all. The computer Adjustment also is turn all the way counter clock wise. I think that is the lean side, but when I turn it to the rich side the car turns off.

what happens if you pull the hose off the aar and leave it open?

idle should go way up

CHTS!

Actually the I figured the spark plugs are the problem

Huh?

The spark plugs are getting fouled up with carbon. My brother had the car before and replaced the rings but never broke them in. So its burning oil, but the plugs get fouled within 15 min off driving.

What plugs? May need to move to a hotter plug.
But this should not be the root problem.
If idle is set all the way lean and you are still pig rich there are other issues at hand. CHTS is suspect. Is it in place? Plugged in? That is what tells your FI to stop pushing fuel once warm.

Quick tip to set rings. Get the engine warm. Run it up to redline in second and let it coast back down in gear. Do that twice more in a row and your rings should be seated. I'd change to fresh oil first.

What's CHTS?

Nevermind I had just replaced the head temp sensor like last month