Mooney78865

I have a 91 coupe that has been throwing code 32 egr codes. I installed a vacuum gauge on the port under the throttle body only to find there was no vacuum at idle and didn't show any vacuum until about 2200 rpm. I checked the port near the rear of the plenum next to the maf sensor and at idle was getting 22 in.
The motor runs great, sprayed for vacuum leaks and nothing. Could the throttle plate be to far closed preventing vacuum below 2200 rpm and preventing enough vacuum to the egr valve?

leesvet

That's because its working EXACTLY as it was designed to.

The TB port is called "ported" vacuum. It does NOT provide any vac until higher rpm so the device is not operated until that time.

Your EGR code comes from 1 of 3 places...

a bad EGR thermal switch in the EGR pipe, loose wire to that switch

or

bad EGR solenoid

or damaged wire to the solenoid or thermal switch.
Fairly common issue.

Mooney78865

Interesting, I hold vacuum in the egr valve, new ac deco, the solenoid checks out fine also new and there is no temp switch on a 91. The vac diagrams I have seen show the vacuum coming from that port. I do not see measurable vacuum until 2200 rpm. Even for ca that's a bit fast in high gear.
My understanding is that if the ECM does not see a change in oxygen sensor readings it would throw a code. With the vac gauge taped to the windshield I see nothing below 2200 rpm.
So I'm thinking, no vacuum, no egr you get code. Everything functions but no vacuum to open the egr, no change to the o2 sensor.
Perhaps I should pull vacuum from another location?