secondaries stuck open, can't figure this one out!

[Huntervf]

Ok, my friend's 92 has had problems with the secondaries sticking open at times. It started last summer, used to be only on occasion but has since become worse. If the car sits for a couple weeks the secondaries will work properly for about 5 minutes, then they'll stick open. Also, when they are stuck open the idle is considerably higher and will fluctuate at times.

Thus far, we've removed & cleaned the secondary butterfly assemblies, replaced the canister on the rear of the intake, replaced the secondary hoses from the canister to the actuators on the intake, replaced the black socket next to the canister on the rear of the intake, and just for grins we replaced the IAB as well. There are no codes.

We're pretty stumped at this point...about the only thing left to replace are the two secondary actuators on the intake, and we'll be doing that this weekend, but I'm suspicious that the problem is elsewhere. Anyone have some input on this situation? At this point, we need it!

 

[sdpatt]

The secondary butterflys are normally open with the engine off and closed by vacuum once the engine starts. Since you also mentioned a high idle speed, it sounds like there may be a vacuum leak to the vacuum accumulator, solenoid valve, or the outlet from the solenoid to the vacuum diaphragm valves. There is also a chance that one of the diaphragms has developed a leak that would only come into play below 4,000 rpm.