rjm65

I have a 79, several vacuum hoses were disconnected by the PO and I'm now trying to put things back together.

Left Diagram - Valve #18 has the two larger hoses attached to it, but does not have the vacuum source hose #20 hooked up.

I'm trying to figure out where to get vacuum from for this valve. Does it get T'ed off from the line that goes to the EGR valve from the thermo switch?

Right Diagram - I notice the EGR valve has two vacuum inputs, one opens and one closes the valve? The vacuum diagram I have shows one input coming off the thermo switch, and the other from a converter valve #14. How does the converter valve work?

Thanks in advance.....
Raymond

linderpat

Raymond - looks like you need one more diagram to finish connecting the hoses properly? I wonder if the PO disabled the smog system and took out other parts that are missing too? Has the car passed the smog test in your state?

rjm65

Hey Ed, The PO had the car smogged as required for the sale, it passed.... but obviously they were lax on the visual portion of it. Plus, many of these test only places don't have racks to raise the vehicle. Pretty hard to verify the EGR is hooked up unless you raise the vehicle.

I hooked up the EGR valve last night. Started up the car and it idled real rough. ARGHHH! I swapped the two vacuum lines (looking at the diagram from the top down and then looking at the valve from the bottom up got the better of me) to the EGR and now it purrs like a kitten. The car had what could be desribed as a slight lope previously, and hooking up the EGR totally eliminated it.

All the cars I've had in the past (GM/FORD) have only had one vacuum line running to the EGR. When enough vacuum was applied it would over-ride a spring that normally kept the valve closed. I think on the 928 that maybe there is one vacuum line to open the EGR valve and another to close it.

Attached are the test results from when the PO purchased the vehicle in 7/07. The results for the test required when I purchased the car is in my glove box. I'll pull it out later and compare the results.

Surprised the EGR is marked N/A. BTW, AFAIK, the car has always been in California (still has blue plates!)

linderpat

Raymond - one other thing - check the famous "y" connector shown in the diagram (part #24 left side of page) - these things are notorious for being broken. It's in the passenger side wheel well, behind the cover - no access thru engine bay. Mine was recently replaced (it was broken) and it cured a hunting idle problem....

rjm65

Will do Ed. I've seen the Y connection when crawling under the car but haven't inspected it. Now if I can just find out if valve 18 (left side of page) takes vacuum all the time or only under part throttle conditions. I think it should be part throttle..... can someone confirm?