IAC valve
Posted: Fri Sep 28, 2007 7:03 pm
I was wondering is the Fast idle valve the same for a 1990 B21A1 the same as a 1991 B20A5?
I just went out and looked at my two engines, and strangely, the answer to your question is no.
The IAC valve from a B20A5 is not the same as the one from the B21a1. The upper port of the B21A1 IAC is oval, where as the B20A5's is round.
I suspect this is caused by the radically different intake plenum design used on the B21. The B20A5 intake plenum is more squarish, and has a second set of runners and a secondary intake butterfly. The B21 has no secondary runners or secondary butterfly.
The fuel rail bolts for the B21A1 are also different than the B20A5. Bottom line is that the B20A5 and B21A1 differ a great deal when it comes to the intake plenum and related components. If you're trying to decide between using a B21 intake or a B20A5 intake, use the B21 model. It's supposedly better.