kenbobc1
Probationary Member
- 2
- 0
- Sep 16, 2013
-
San Diego,
California
All,
My faithful 1990 Eagle Talon TSI has finally failed CA smog, via the EGR functional check. The tech could not hold suction he applied to the EGR valve. But I'm confused by a couple of aspects, and apologize in advance for the rambling account.
First, my EGR valve actually has 3 hose ports, two on the cap above the diaphragm, and one below. The two on the cap go to the throttle body and the EGR Control Solenoid, respectively. If I disconnect both of those at their far ends from the EGR valve, plug one and apply suction to the other, the suction holds and the engine stutters and almost stalls, like it is supposed to.
However, the EGR valve test in the shop manual shows that you're supposed to be able to apply a hand pump to one EGR port, without unplugging anything else, draw and hold suction, and stutter the engine. (This is exactly what the smog tech tried to do) But the diagram in the manual doesn't show an EGR valve with the two ports on top and a side mount like mine, so I'm sure the diagram doesn't apply directly to my CA turbo configuration, and makes me doubt if the procedure is fully correct too. The only way the single port test could work is if the other port is the one connected to the solenoid, and that solenoid is closed.
So I did the shop manual test on the solenoid as well, when no voltage is applied it doesn't hold suction, when I supply it with 12V from the battery it clicks and does hold suction, just like it's supposed to. So while the solenoid was disconnected, I checked what voltage the connector was supplying at idle, and turns out it's about 6V. This certainly explains why you wouldn't be able to hold suction through the EGR to that solenoid, but I still don't know if I should be expected to at idle. And 6V seems like a bad value to provide to a solenoid, shouldn't it be either something close to 0 or 12? Does this mean that the solenoid driver in the ECU is bad? Or is the measurement across the open connector just not valid without a load?
And since all ends of this EGR vacuum circuit eventually go to the throttle body at one point, I'm not sure what the correct solenoid sense is to apply vacuum to the EGR. i.e. does solenoid closed allow vacuum from one end to build up and open the EGR valve, or does solenoid open apply vacuum from the other side of the solenoid to open the EGR valve?
Again, sorry for the rambling, but would appreciate your thoughts.
Ken
My faithful 1990 Eagle Talon TSI has finally failed CA smog, via the EGR functional check. The tech could not hold suction he applied to the EGR valve. But I'm confused by a couple of aspects, and apologize in advance for the rambling account.
First, my EGR valve actually has 3 hose ports, two on the cap above the diaphragm, and one below. The two on the cap go to the throttle body and the EGR Control Solenoid, respectively. If I disconnect both of those at their far ends from the EGR valve, plug one and apply suction to the other, the suction holds and the engine stutters and almost stalls, like it is supposed to.
However, the EGR valve test in the shop manual shows that you're supposed to be able to apply a hand pump to one EGR port, without unplugging anything else, draw and hold suction, and stutter the engine. (This is exactly what the smog tech tried to do) But the diagram in the manual doesn't show an EGR valve with the two ports on top and a side mount like mine, so I'm sure the diagram doesn't apply directly to my CA turbo configuration, and makes me doubt if the procedure is fully correct too. The only way the single port test could work is if the other port is the one connected to the solenoid, and that solenoid is closed.
So I did the shop manual test on the solenoid as well, when no voltage is applied it doesn't hold suction, when I supply it with 12V from the battery it clicks and does hold suction, just like it's supposed to. So while the solenoid was disconnected, I checked what voltage the connector was supplying at idle, and turns out it's about 6V. This certainly explains why you wouldn't be able to hold suction through the EGR to that solenoid, but I still don't know if I should be expected to at idle. And 6V seems like a bad value to provide to a solenoid, shouldn't it be either something close to 0 or 12? Does this mean that the solenoid driver in the ECU is bad? Or is the measurement across the open connector just not valid without a load?
And since all ends of this EGR vacuum circuit eventually go to the throttle body at one point, I'm not sure what the correct solenoid sense is to apply vacuum to the EGR. i.e. does solenoid closed allow vacuum from one end to build up and open the EGR valve, or does solenoid open apply vacuum from the other side of the solenoid to open the EGR valve?
Again, sorry for the rambling, but would appreciate your thoughts.
Ken
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