1984 El Camino Conquista failing first smog check ever

[Clone TIE Pilot]

When the solenoid is de energized , it is open and allows vacuum to the EGR valve. When the solenoid is energized, it closes and cuts off vacuum to the EGR valve. The usual manner a EGR solenoid fails is that it loses its ability to close and and shut off EGR operation when energized. This allows the EGR to operate when its not supposed to. I guess the solenoid can become stuck closed but more often they develop leaks in the closed position.

Full time EGR operation may cause issues like idle stalling.

 

[Steve C]

I have an El Cam in California as well. I hate to tell you this, but the nox and co goal are moving higher. The state is making it harder to pass.

 

[MarcD]

Ok, I successfully disassembled the EGR solenoid…here it is:

You’ll notice a deteriorated fiber gasket that should seal the inlet tube against the coil body when assembled, right here:

If the seal fails, the solenoid body won’t hold vacuum to any port, energized or not.

I believe this is how the ports are dedicated:

I believe when there’s a complete circuit to the terminals (12v feed and whatever ground the ECM provides), the energized coil overcomes the spring’s tension, pulls the conical slug away from the atmosphere vent, simultaneously closing off the vacuum from the carb port by seating against the end of the inlet tube. This vents the EGR to atmosphere, closing the valve.

When all operating conditions are met (warm engine, transmission in drive, throttle opened), the ECM opens the ground and the solenoid coil de-energizes and the spring pushes the conical slug against the atmospheric vent, seals the chamber, opens the inlet tube to carb vacuum and allows vacuum to flow to the EGR.

In the old days, just the ported carb
vacuum was enough.

Unfortunately, I think mechanical wear inside the coil is keeping the coil’s magnetic field from moving the conical slug when assembled with the spring. If I delete the spring, I can hear the slug clicking when current is applied to the contacts.

Since the original solenoid is discontinued and junkyard cars are either stripped or in similar condition, I searched a few forums and learned of an available substitute. It Standard Electric part # VS25, available at FLAPS for a 1995 Cadillac 4.9.

Has anyone here had any luck with this part?

Thanks again to all!

Marc

 

[86LK]

Ok, I successfully disassembled the EGR solenoid…here it is:
View attachment 219620

You’ll notice a deteriorated fiber gasket that should seal the inlet tube against the coil body when assembled, right here: View attachment 219621

If the seal fails, the solenoid body won’t hold vacuum to any port, energized or not.

I believe this is how the ports are dedicated:

View attachment 219622

I believe when there’s a complete circuit to the terminals (12v feed and whatever ground the ECM provides), the energized coil overcomes the spring’s tension, pulls the conical slug away from the atmosphere vent, simultaneously closing off the vacuum from the carb port by seating against the end of the inlet tube. This vents the EGR to atmosphere, closing the valve.

When all operating conditions are met (warm engine, transmission in drive, throttle opened), the ECM opens the ground and the solenoid coil de-energizes and the spring pushes the conical slug against the atmospheric vent, seals the chamber, opens the inlet tube to carb vacuum and allows vacuum to flow to the EGR.

In the old days, just the ported carb
vacuum was enough.

Unfortunately, I think mechanical wear inside the coil is keeping the coil’s magnetic field from moving the conical slug when assembled with the spring. If I delete the spring, I can hear the slug clicking when current is applied to the contacts.

Since the original solenoid is discontinued and junkyard cars are either stripped or in similar condition, I searched a few forums and learned of an available substitute. It Standard Electric part # VS25, available at FLAPS for a 1995 Cadillac 4.9.

Has anyone here had any luck with this part?

Thanks again to all!

Marc

you mean this?

Standard Motor Products VS25 Standard Motor EGR Valve Control Solenoids | Summit Racing

Free Shipping - Standard Motor EGR Valve Control Solenoids with qualifying orders of $109. Shop EGR Valve Control Solenoids at Summit Racing.

www.summitracing.com

these are for Chevy sbc (but apparently only for 1987-2002)

CHEVROLET Chevy small block Gen I EGR Valve Control Solenoids - Free Shipping on Orders Over $109 at Summit Racing

Find CHEVROLET Chevy small block Gen I EGR Valve Control Solenoids and get Free Shipping on Orders Over $109 at Summit Racing!

www.summitracing.com

these are for the 305 (but apparently only for 1987-1995)

CHEVROLET 5.0L/305 EGR Valve Control Solenoids - Free Shipping on Orders Over $109 at Summit Racing

Find CHEVROLET 5.0L/305 EGR Valve Control Solenoids and get Free Shipping on Orders Over $109 at Summit Racing!

www.summitracing.com

you can also narrow it down to the engine code as seen below

 

[ELCAM]

Pretty sure the wiring connector is different on all the later solenoids.

This is the diagram for the Chevy Pickup, think it is the same as the VS12.

This is the Cadillac valve the nipple with the springs on either sides is the vent.

 

[MarcD]

I jury-rigged a vacuum tube directly from the the ported vacuum on the carb to the EGR, bypassing the dead solenoid, and the tech performed a manual dyno run. Numbers were great, with NOx greatly reduced.

With evidence that the catalytic converter and the rest of the system was capable of passing; I replaced the EGR solenoid with the VS25 unit and a new pigtail connector.

Passed inspection!

Thanks to all for the suggestions and knowledge. I’m sure my dad, who passed 10 years ago at 94, is smiling at this exercise in perseverance and pleased his El Camino soldiers on.

Best,
Marc

 

[79 GP 4 speed]

Sounds like it would have been easier to move out of California.

 

[Clone TIE Pilot]

I jury-rigged a vacuum tube directly from the the ported vacuum on the carb to the EGR, bypassing the dead solenoid, and the tech performed a manual dyno run. Numbers were great, with NOx greatly reduced.

With evidence that the catalytic converter and the rest of the system was capable of passing; I replaced the EGR solenoid with the VS25 unit and a new pigtail connector.

Passed inspection!

View attachment 219824

Thanks to all for the suggestions and knowledge. I’m sure my dad, who passed 10 years ago at 94, is smiling at this exercise in perseverance and pleased his El Camino soldiers on.

Best,
Marc

Good to know of a substitute replacement part.

 

[schwim]

With evidence that the catalytic converter and the rest of the system was capable of passing; I replaced the EGR solenoid with the VS25 unit and a new pigtail connector.

Hi there Marc,

Is there a polarity to the wires that I need to follow or does it not matter which wire connects to which pin in the pair?

 

[jiho]

I have an El Cam in California as well. I hate to tell you this, but the nox and co goal are moving higher. The state is making it harder to pass.

New standards can only be required of future model years, they cannot be applied retroactively to vehicles that were already on the road.