EGR Valve Test - Vacuum ?

[dubyehnel]

Having problems with high NOx and not passing Colorado emissions, so I went to test my EGR valve and can't seem to pull a vacuum with my mity vac hooked up to the EGR valve port that goes to the modulator. I thought there might be a crack in the hose that goes from the EGR valve to the intake plenum, but when I pulled that hose from the plenum (while still hooked up to the EGR valve from the other side) and plugged the end with my finger I could pull a vacuum. Could there be a vacuum leak in the intake somewhere that is allowing this to happen. I feel like I'm missing something simple. Thoughts?

Thanks

 

[dubyehnel]

Could this be a case of the engine needing to be up to operating temperature?

 

[blkprj80]

Is there a vacuum diagram pasted on the underside of the hood?

 

[Pin_Head]

The VSV under the intake is supposed to shut off the line to the modulator when the engine is up to temp.

 

[jatree]

Having problems with high NOx and not passing Colorado emissions, so I went to test my EGR valve and can't seem to pull a vacuum with my mity vac hooked up to the EGR valve port that goes to the modulator. I thought there might be a crack in the hose that goes from the EGR valve to the intake plenum, but when I pulled that hose from the plenum (while still hooked up to the EGR valve from the other side) and plugged the end with my finger I could pull a vacuum. Could there be a vacuum leak in the intake somewhere that is allowing this to happen. I feel like I'm missing something simple. Thoughts?

Thanks

I'm having this exact issue. Would love to know how you proceeded from here.

 

[Tools R Us]

I'm having this exact issue. Would love to know how you proceeded from here.

IIRC, the VSV is normally open, is closed by the ECU when EGR is needed. So if for whatever reason, you want to apply vacuum to the EGR, the line to the VSV needs to be pinched or capped.

 

[jatree]

IIRC, the VSV is normally open, is closed by the ECU when EGR is needed. So if for whatever reason, you want to apply vacuum to the EGR, the line to the VSV needs to be pinched or capped.

Thanks Tools, good timing. I really didn't want to get into removing the EGR Valve today so this morning I gave it multiple thumps with the rubber grip of my wrench. For some reason I was under the impression that pinching the DS Vacuum Hose of the EGR "T" alone would stall/stumble the engine but it didn't. However, I learned pretty quickly that if I pinched the DS side and then applied vacuum directly to the PS of the "T" I could get it to stumble with a single pump. So I think the EGR Valve is good? I'm surprised that the FSM test doesn't mention pinching it:

Does applying vacuum without pinching work for other people? I wonder if pinching the other vac hose allows you to generate greater vacuum pressure, which moves a sticky valve...

When I get a break from the rain, I plant to test the VSV (through the connector) and new Modulator. Interestingly, this new modulator (blue top), has two filters under the cap. The top one with the coarse/puffy side up and the bottom with it down.

 

[jatree]

Can someone confirm how to do the EGR functional test above? The vacuum modulator I replaced as part of this post last year failed again and I need to check if my EGR Valve is working next week. Last year, simply pulling vacuum from the passenger side port of the EGR Valve didn't do anything, but if I pinched the driver's side line and then pulled vacuum, the engine stumbled. Has anyone done this test and if so, how does a functional valve behave?

 

[Stecz]

Testing myEGR valve...
If I draw a vacuum on it with my mitey vac, it moves the diaphragm, but bleeds down immediately. So that seems like it's bad.
Also, if I move the diaphragm, I still can't blow air through the valve. Also seems bad. (Air can't get through path exhaust would follow.)

Sound right?

I cleaned EGR passages 12k miles ago, so maybe not setting the cel ?

If the valve is bad, could that affect my power brake booster leaking down?
Or they both just failed at the same time.

Any issue with replacing the studs that attach the EGR with bolts?