Secondaries actuator solenoid valve

[A26B]

Originally Posted by S.hafsmo

Well that's a bit disappointing. I was just about to buy one of those. Surely there must be solenoids one could modify for the purpose? I assume these are molded shut/not serviceable?

They're not expensive and a little bit of vacuum leakage can still be compensated for by the Vacuum pump as long as there are no other significant vacuum leaks in the system. Maybe you will have better luck than I did regarding vacuum leakage.

They weren't intended to be serviced, but they can be taken apart by bending the metal tabs on the end. The internal parts of the valve itself can be removed. My thoughts are to try & modify the seat to seal better. It's been a couple of years since I had one apart but I seem to recall the seat looked like a small piece of cardboard which I was thinking about replacing with a piece of softer, rubber material.

If valve end can be modified to seal, the same technique could be applied to the original solenoid valve too, as long as the electrical solenoid is still functional.

All is not lost, just needs a little McGyver tweaking.

[mike100]

These are the same (except for the bracket) as early 90's 3 port EGR vacuum solenoids. The egr solenoids have a brass restrictor jet in the pipe that can be plucked out with a sharp pick then it is exactly the same 12v vacuum switch as the LT5 version of it.

I used this for my muffler vacuum flapper mod. The p/n is in one of my posts about that, but you can also find them on pre-northstar 4.5l and 4.9l cadillac engines.

[S.hafsmo]

Appreciate the input. I'll try to order one of each type solenoid and see what works best. I've used to do emergency solenoid repairs on larger solenoids by gluing a smal piece of mig welding glove leather on the sealing surface of the actuator plunger, where the rubber has cracked/failed, but these are larger solenoids on 30 bar systems.

I've definately got a leak, as I'm unable to hold any vacuum on the "under plenum side" of the secondaries vacuum system. Assume it's the check valve letting in air from the plenum.

Is it correct that the differential pressure sensor (locaed below the ECM) is connected to the other side of the solenoid of the secondaries vacuum system? Though I suppose that would'n help much, as the solenoid would currently have this part of the system vented to atmosphere. At first I thought that would be a way to confirm actuator leakage without removing he plenum, but that does not seem to be the case.


Edit: ordered one with PN# 1997207. Will check for vacuum leaks before installation.

[Top Toy]

Best fix for any secondary parts issues is to get rid of the secondaries. I started having issues several years ago, eliminated the secondaries and haven't looked back since. Absolutely no down sides to performance. Maybe a hit to emissions but I'm exempt with classic plates so can't speak to that.

Sent from my XT1254 using ZR-1 Net Registry mobile app

[S.hafsmo]

That't not really an option for me. People tend to speak of the LT5 as if the 4 cam, 32 valve design is what makes it unique, while in reality it's the pushrods that make the other generations of corvette unique. The use of pushrods today is almost a quirky signature, like the Mazdas Wankel (yes, i exaggerate, and yes, I know pushrod tech has benefits).

I bought the car pretty much because of the way the secondary system is designed, with the flaws that might follow. As I tend to like such odd designs.

[mike100]

A quick diagnostic would be to 'T' into the vacuum line going to the under ecm vacuum sensor. When the pump is running and the solenoid circuit connected to the pump during secondary operation, you will see about 13" of vacuum on a gauge. The needle will quiver a little with the pulsations of the electric pump. If it is less than that, you probably have a leak.

[S.hafsmo]

I've already confirmed a leak on the pump (/reservoir) side of the solenoid, so I don't think it would give much more info to test again with the solenoid active (vacuum to actuators).

Is the purpose of the diff. press sensor below ECM to confirm vacuum after the solenoid/at the actuators, upon activation of the secondary system?

[mike100]

Originally Posted by S.hafsmo

I've already confirmed a leak on the pump (/reservoir) side of the solenoid, so I don't think it would give much more info to test again with the solenoid active (vacuum to actuators).

Is the purpose of the diff. press sensor below ECM to confirm vacuum after the solenoid/at the actuators, upon activation of the secondary system?

Yes, and if I understand the system operation correctly, to not continue to operate all 16 injectors if it doesn't think the secondary blades are opening.- but it will set a code if there is a significant leak.