EGR valve VX

[kais3r]

Does anyone know how these EGR valves operate?

When they open and close...
Either throttle or temperature related

Is it always closed at idle or does it open based on idle temps...

Whether they should create a tight seal and let zero gasses through when in a closed position...

Just trying to to test and determine a possible fault with one on my car, I've tested it with a cold running engine and blocked off the TB inlet and it seems to raise the revs at idle under this scenario, but it shouldn't change anything if the valve doesn't let any flow through in a closed position, so it may be leaking or faulty, but once I know the workings of it I'll be able to determine what's going on.

Find it strange that if it's meant to be closed, and I block off the TB inlet, that the revs go up at idle, I'm thinking if it's NOT leaking then there shouldn't be a change in revs either way.

Thanks

 

[dirty hands]

on the commy
the egr is an electronic valve not vaccume...they do carbon up
and works something like a solenoid . it is part of the EFI system The Maf and 02 sensors are part of this
the current opens and closes the valve to let the heated unburnt fuel /gases come back into the inlet manifold to be recylced

only a small hole ..the egr valve works all the time....

When it is closed it does seal the passage ...not good

,supposed to give better emissions and economy

one the codes does tell you if it is faulty

GM electronic egr system explained .( has a fix - but bad ecu found )

https://www.youtube.com/watch?v=te_kapz-fj4

 

[Brett_jjj]

Yeah, The max Ellery VT to VZ workshop manual says the following about the EGR.

"The linear EGR valve is activated if the following conditions are met:
1)Engine is at operating temp.
2)Above idle speed.

The sensors listed below are monitored by the PCM and adjustments to the EGR valve pintle position are made accordingly:
1)Engine coolant temp sensor(ECT).
2)Mass air flow sensor(MAF).
3)Throttle position sensor(TPS).
4)Engine RPM."

 

[kais3r]

Thanks guys, but any idea why it would rev higher at idle with a cold engine (haven't tried hot) when I disconnect the EGR TB inlet pipe and block off the TB hole? Shouldn't be anything going through it anyway while closed so revs should be the same?

 

[Brett_jjj]

Both my VS and my VY idle faster when started from cold, that's just normal. Id try cleaning the EGR valve as theyre known to carbon up and leak causing idle problems..

 

[kais3r]

Yes they idle faster when cold but let's just disregard the temp for a moment.

If this valve doesn't ever open during idle, then the only way the revs can rise when removing the EGR TB inlet pipe from the TB and blocking the TB inlet hole, is through a leaking EGR valve right?
And I mean it rises by 400-500RPM.
What would cause the revs to go up when I blocked off the TB hole from the EGR pipe? EGR is meant to be closed anyway.

 

[Brett_jjj]

Yeah, Id say the EGR valve is leaking, probably just dirty.. The engine revs will change whenever the fuel/air mixture changes. Blocking off the EGR port from either exhaust or atmoshpere changes the fuel/air mixture)

 

[Nut Kracker]

As per the FSM.

Checked the Fuse....?



Or may be a leaky gasket (3)....?

 

[kais3r]

The fuse being (33 engine sensors)? Yes it's fine.

Gasket looks fine too, no signs of escaped carbon along either side of the face.

I am wanting to give it a clean though but doesn't look like it can be opened up, any ideas or should I just flush it through with cleaner?

The pin does work, pulls up when voltage applied and drops again when voltage removed, though the spring is quite soft, shaking the valve gently will allow the pin to move off it's seat, I measures the resistance, 180grams of downward pressure will move the pin 1mm out of it's seat.

I don't know if there's any electrical closing force on it when connected but the vacuum applied to it from the plenum does work in the direction of pulling the pin into the seat.

 

[kais3r]

Don't think there's anything wrong with EGR valve anymore, seems to be ok.

I did a compression test and looks like cylinder 2 is buggered, it's about 35psi below the rest which are about the same.

Any chance it's a dirty valve seat or most likely a bad valve or rings?