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I've been working on a 1995 9000 CS.
I've got an EVAP valve CEL. It blinks 8 times. The CEL turns on as soon as the valve starts ticking - not before not after. My 3 valves that I have tied independently of each other test ok and behave the same. I just today replaced the charcoal canister. My three gascaps all behave the same.
I've done some searching on here and someone sent me the EVAP valve section from his "Service Manual: Engine Management System, Trionic
OBDII" Thanks Street.
Symptoms:
Mechanical:
I've pulled off the line on the manifold that comes from the EVAP valve.
Engine Off, Ignition Off - I can suck on the line (no resistance)
Engine Off, Ignition On - I can suck on the line (no resistance)
Engone On Valve Not Yet Ticking - I can not suck on the line (I get and maintain vacuum in the line) No leaks,
Engine On Valve Ticking - I can suck in pulses concurrent with the valve ticking.
I can not blow though line at any time. So the boost out protection is working properly. And there are no leaks here.
I sucked on the line that comes from the tank. I can suck on it (no resistance). I can not blow though it (I can pressurize and maintain pressure in the line). So the two way valve works, and the line does not leaks here.
Electrically:
Everything says that the valves should have a 26 ohm resistance. I have three used valves and they all share a mid-40s ohm resistance. I've even tried weiring up a 20 ohm resistor on the ground side of the valve. It changed nothing.
I have read from Townsend's site and Street's manual that the EVAP Valve is "activated by being grounded via pin 27 on the ECM" and that pin 27 is connected to pin 21 "in order to permit diagnosis"
I checked my ECU connector. If I go by my connectors indication of pin 21 and 27 I find that I have no pin 21. I went and probed my ECU connector for continuity on to the evap valve. On the wire that gives the valve +12 I find varying degrees of continuity to pins 48, 49, 31, 32, 1, 3, 4, 5, and 6. On the wire that gives the valve it's signal from the ECU I find connectivity to pin 27 only. I have not found any disconnected wires.
When properly installed my valve does exactly what I've read it supposed to: be closed on start, start ticking after a little bit, stop ticking every 4 minutes for 30 seconds.
So:
Any insight as to what is going on here? Should I "add" a pin 21? I did have problems with the pinout in the book being wrong. I had to "shift" all the pins over two in order to make it accurate. Is the book wrong for my model year? Did they change OBD1 vs OBD2 EVAP valves? What about the whole 12v open 0v closed issue? Should I crush this car?
posted by 24.10.98...
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