Join Date: Jul 2003
Location: Memphis, TN
Bronco Info: '83 VIN & title on '93 frame/body w/'95 4.9L & EB paint
I don't have any JYs within 30 miles of my house either, but that doesn't affect the temperature at which PVC softens in a truck engine compartment, or the HUGE effect 15psi has on soft PVC.
The check valve prevents the reservoir from supplying vacuum to the manifold. IOW, w/o the check valve, it's not really a reservoir - just an echo chamber. It will have no direct effect on the CEL. But without vacuum, the TAB, TAD, & EGR can't work right, and THAT may turn on the CEL.