I have two IACVs, they're both fit my intake manifold but one has a large opening and one has a smaller opening:





Is there a difference between the two?

Thanks!

 

Yes, one has a smaller hole. Heheheh

Seriously, the one with the larger hole will idle slightly higher with a stock ECU in some cases. If you have a tuneable solution, you can adjust the IACV duty cycle up or down to compensate for this.