This '91 injector housing was quite a surprise. It was removed for porting. We discovered that it had severe core shift for cylinder number five.

All '90 - '92 injector housings have core shift that varies from .5 to 2 mm. The factory chamfered the tops of the injector housing ports to match them to the plenum. The same variation occurs on the lower ends of the ports. The cylinder heads are chamfered to match the injector housing ports. Because of the severe mismatch, this injector housing should have been rejected at the factory. The off center deviation for both of the number five ports is so great that the secondary port was actually feeding into the primary port of the cylinder head. This severe misalignment is a very rare problem.