Smog help!!!!!
 

i have an 87 supra. i put a 91 motor in and a new catalytic converter. its a non turbo automatic with no mods. it passes perfectly at idle but off idle it fails, not by much but it does. my first thought is to change the ECU considering that the intake manifolds are different which could cause a different air fuel mixture. what are your thoughts????? another tid bit of info is that the car is originally from washington. not sure if it makes a difference but any info you could give is much appriciated. thank you.

Do you have the emission printout? I'd be curious to see how it failed and by how much. Off the top of my head, high NO numbers could be a faulty EGR system and therefore not necessarily be catalytic converter related

If you've got a different manifold on one of the engine's then it's from a difference model Toyota. Swap over all of the different components from your old engine.

BT, you may be right, if it's a Cressida 7M the EGR system probably isn't even there.

How is it failing? Which levels are too high? NOx?

Yea if the intakes r different then it's a Cressida motor the intakes on the supra nonturbo always been the same From 86-1/2 to 92