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Testing If Vct Is Working Properly

Chi100188

By Chi100188,
in Engines & Forced Induction

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urtwhistle Proficient

urtwhistle

Posted
Posted

Yeah I'm aware of that part Rolls, What I probly should have mentioned is that I'm trying to find the source of why my Rb3025 is so laggy. when it shouldn't be. It's booked in with a shop for diagnosing next week to see if I have missed something obvious when I did the timing.

I guess what I should have said is at idle should the solenoid be seeing any voltage at all? I have 10V @ idle is this normal? and I also have 10V @ 2500 RPM ( with AC on, Car in gear) I would have thought it would be either 0v or 14v depending on which way it defaults to. I also wonder if the 34 needs more load on the motor to trick it to trigger when the car is stationary compared to the R33.

Either way its going to a shop who hopefully will figure out whats causing the issue/s.

Rolls Grand Master

Rolls

Posted
Posted (edited)

it should be seeing voltage at all times as the ECU grounds the solenoid, it doesn't provide power.

Only real way to test if it is getting a signal is to put a current meter on it really, voltage may droop a little when it pulls the voltage but if it is wired to the battery then there won't be any droop as it is only 1amp. If it isn't making a decent click noise then you can rule it out as broken though.

R34 is smart, I think it needs a few things, TPS to indicate throttle, be in gear and also have your speed above 10kph is what I've heard in the past.

Edited by Rolls
urtwhistle Proficient

urtwhistle

Posted
Posted

Cheers Rolls,

Good point on the earthing. I wired the solenoid directly to the battery and it made a very audible click. So I believe its definitely operating. But whether it's working properly under it normal conditions I'm yet to see. Will keep you informed with what I find. I think you might be on the money with the 10kph bit too.

I set the data logger to record the VTC output and with the car stationary I couldn't get the ecu to trigger. But it appears to trigger an output once moving.

JonnoHR31 Grand Master

JonnoHR31

Posted
Posted

if you really wanna test the solenoid pull it out of the head and make sure it blocks off the oil gallery when earthed out. if it does and its getting triggered by the ecu then its working, the only way for the cam not to advance then is if theres something wrong internally which is very rare

urtwhistle Proficient

urtwhistle

Posted
Posted

Hey Rob I did that as mentioned in my 1st post

I removed the VCT plug and applied power directly to the solenoid and it clicked as it should have. I measured the voltage at the plug @ idle and it had 10v but I couldn't get it to trigger and go any higher.

which with out rigging the multimeter up and driving around was all that I can tell. But it has got me thinking, Rolls said that the VCT solenoid earths through the ecu. so therefore I wonder if he is possibly wrong on the part that it should always be seeing current. normally with solenoid's or coils there either on or off. supplying current all the time would just create heat especially if its neither on or off.

But all this really doesn't matter because its now at JPC for them to look at and find the problem.

rob82 Mentor

rob82

Posted
Posted

What rolls said was correct and if you put a multimeter across the pins then you should only see either 13volts when the solenoid is energized or 0v when off.

I don't believe the r34's are current controlled drivers but it maybe worth checking to see if the power wire is connected to ignition(as the r33 is) if it is then it should be the same as the r33.

And as for cam phasers not working - I was diagnosing about 1 Subaru a month at my previous job. So I wouldn't rule that out.

Rolls Grand Master

Rolls

Posted
Posted

The positive pin will always have 12v, the earth pin will only have zero volts when it is on.

So fi you are earthing on the chassis it will always show 12v on the solenoid, so make sure you have both pins in the plug, not just the positive.

urtwhistle Proficient

urtwhistle

Posted
Posted

Hey guys, yeah when I was testing with the multimeter I never actually earthed to the chassis on either pin. I was measuring voltage between the two pins on the plug.

Therefore from that it would be pretty safe to assume that its earthing constantly. Doesn't matter any way cos the cars in the shop and I can't test it.

Cheers for all your help guys, it was very helpful.

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