I decided to troubleshoot the Pair Valve System. The Pair valve and its VSV passed but I think I either have bad wiring, a bad ECU or a bad TPS.

I ran through the Factory Service Manuals battery of tests, no vacuum leaks, the Pair valves diaphragm is good, and it will seal with no vacuum applied. The VSV electrical and vacuum functions are working, so everything passed except the last engine running test.

(c) Race the engine above 2,000 rpm and quickly close the throttle valve. Check that the bubbling noise stops momentarily.

Which means that no electrical signal is being sent to actuate the VSV to apply vacuum to the Pair. I did test for vacuum from the intake to the VSV, and there was.

I still have yet to setup a switch to manually trigger the VSV to apply vacuum to the Pair, but I have now doubt that it wouldn't work. Also, if I am correct in thinking that in order for the ECU to electrically actuate the VSV, it would simply ground the VSV. The two wires going to the VSV are White/Red (tested 12V+, same as +B in the Diagnostics Plug) & Green/Red that goes to the ECU. This is what leads me to thinking I could have bad wiring to the ECU, a bad ECU or a bad TPS that's not signaling the throttle has been let off to signal for Pair VSV function.

Also, would it be feasible in thinking that I could run test (C) above again, and have the VSV electrical unplugged. I would use a multimeter to check for continuity between the Green/Red wire and ground. Or could this mess something up? My thinking is that this would tell me if the ECU is actually grounding the connection or not.

What do you guys think?



Parts 1 A&B / Part 2 / Part 3 (You are here)