Vct Help!

[JonTurpening]

First off I'm not sure if my VCT is working. I have power going to the valve and I do hear a "click" coming from it when the throttle plate is opened.

The thing is it makes no difference whether I plug the valve in or leave it unplugged. I've had it to the dyno 3 different times and the last time I made sure it was "clicking". The results were the same plugged in or not!

Can someone tell me how I can test it to make sure it's working? I know I have 12v going to one side and like I said above I can hear and feel a "click" from it when I open the throttle plate and once again when I close it.

Does it work off oil pressure? Can the passages get clogged? The car is making good power (379.5rwhp) but there is not 1hp difference plugged up or not!

Thanks again guys for all your help!!

[QWK32]

you wont notice a difference in overall power. but there will be a difference in the low down power. so if it is working properly you will have slightly more power at say 3000rpm with it plugged than you would if you unplug it.

best way to look at this is to do a dyno run with it plugged in and one with it unplugged. then overlap the printouts of the two runs to see where it slight gain is.

Edited June 26, 2008 by QWK32

[blind_elk]

VCT generally operates between about 1500 rpm and about 4500 rpm. So outright power at 6000+ shouldn't vary.

[JonTurpening]

I have. That's just it. There is no difference in power at that rpm range with it plugged in or not.

Here are two dyno plots the only difference in them is that we added about 1.5-2psi of boost and one had the valve plugged in and the other did not. There is no difference in the lower rpm range at all. (The 379 was plugged in and the 363 was not. we did a run at the same boost level with it plugged in and it was the same I just didn't get a print out of it.)

you wont notice a difference in overall power. but there will be a difference in the low down power. so if it is working properly you will have slightly more power at say 3000rpm with it plugged than you would if you unplug it.

best way to look at this is to do a dyno run with it plugged in and one with it unplugged. then overlap the printouts of the two runs to see where it slight gain is.

Edited June 26, 2008 by JonTurpening

[blind_elk]

Not made easy by having different horizontal scales. If you look really closely, there are differences between the "with VCT" and "without VCT" graphs.

But you made two changes - boost and VCT. You need to run back-to-back, with only 1 change, namely VCT on / off. When you start changing other variables, you can't possibly tell which change had the effect. And running them a month apart could also interfere with the results - different weather, dyno recalibrated, different ramp rate, who knows.