Jump to content
SAU Community

Recommended Posts

well last week i was getting car tuned had a few problems in the past such as cas,coil packs, exhaust cam gear set on 2 degrees retard all been fixed now and the car still wouldn't make any power down low until 5k rpm the power would just shoot up so the tuner reckon it was the VCT not work so i changed the solonoid but i want to test if the vct is really work or not

First thing do this:

1. Start car

2. Remove plug from VCT solenoid

3. Set up test light onto VCT solenoid plug

4. Get some one to put car into gear (obviously holding the clutch in) and rev the car

The test light should light up above the 1200ish rpm and stay lit until the 4500ish rpm. This will tell you that the ECU is actually giving power to the solenoid.

The only way now is to put it onto a dyno and do two runs back to back plotted on top of one another. One with the VCT plugged in, one with it unplugged. If both runs are identical you know you have a problem with the solenoid itself. It is pretty rare to have a solenoid fail though.

Edited by PM-R33

or poor mans seat of the pants approach.

Give it a bootful in low gear to 4k rpm with vct plugged, ensure you stay below the speed limit.

step 2.

Unplug vct and repeat, if run two feels like arse... vct is working ok in run one. if they feel the same... vct is broken

what ecu are you using? may have to setup vct as an output.

Its running a PFC.

we have have heaps of issue with the car and has been to the tuners now 3times and still no complete tune, so the owner is getting abit dishearten hence why we want to work out if the VCT is working.

We did a swap yesterday using the old VCT solenoid from my old engine, however we are not 100% sure if the solenoid was the problem or if we needed to swap the cam gear aswell

You should be able to hear the solenoid click when you pull the throttle when under the bonnet, this would suggest it is working... It's a noticeable noise

The car has to be in gear(just not in neutral) for this to work.

so i pretty much sit in the car put it in first clutch in rev it till 4000 rpm to and get another person to have his ear in the engine bay to hear a click or not or alternatively just drive the car with the vct plug in then take it out and see how the drive is after that?

  • 2 weeks later...

Where is the VCT solenoid in the engine bay? Also when does it switch on, 1500 - 4000 rpm? or is it 5000 rpm.

Just got my eboost street and it has a window aux function which I am planning on using to control my VCT.

Also does the VCT activate when you ground the relay, or provide power to it?

Cheers

  • 1 year later...

Hey guys I'm wondering if I have potential problems with VCT on my R34 also.

I have tried testing it as well as I can until it goes on a dyno, so please give me your thoughts.

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.

I tried setting the power fc trigger points at 0 4500 and 7400rpm and 7400 gave the best boost response for some reason.

I also tried driving around with it plugged in and unplugged and there was no difference.

You need to put it on a dyno and wire it on all the time, do a power run, then unplug it and do another dyno run.

Now overlay the two graphs, where the graph with it permanently on dips below the graph with it always off should be your ultimate switch over point. Doing anything other than this is guessing and will give sub optimal results.

53948234.jpg

edit it is possible the solenoid is jammed, I had to hit mine with a hammer and then pulse it on and off 10 times to get it to start clicking.

Edited by Rolls

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Similar Content

  • Latest Posts

    • In a few years from now, you'll regret that. It'll eat away at you, knowing the truth of the ugly hiding beneath the beautiful exterior... 😛
    • I don't think the G2 profile is particularly dangerous for the engine per se, more just are you actually ok with the turbo lag trade-offs? If the answer is yes then go for it. I personally don't think I'd be ok with it because I spend so much time at lower RPMs and I really enjoy the feeling of being able to stay in 5th gear on the highway and just roll into the throttle to get boost. Or staying in 3rd gear on "gentle canyon cruises" without feeling the turbo lag too badly. The 525 pump should be able to run flat out on factory lines but I would bet the pressure drop from pump to regulator is quite impressive. I don't know how much it would be exactly but I've seen figures like 30 psi thrown around.
    • It's interesting seeing everyone talk about what level of risk they are happy to tolerate.  Building a GTR always has a level of risk, you could be that lucky guy that drops 20k on the engine build alone and still has the thing go pop on the dyno. Life is fun like that.  The way I see it, the thing is a toy to be enjoyed. I'd be happy to turn up the power on stock motor and limit the risk with sensible tuning and engine protection. If it still goes pop, it is what it is. The car isn't a daily driver so it can happily sit while a plan is made to sort it out.  Given this thing will be a street car only, I really feel it's worth the (relatively small if managed well) risk to turn the power up to around 350KW on e85.  I don't think anyone getting into the skyline game now is doing it out of logic. Surely it is a purely emotional decision so I'm not sure how important it is to think about the engine build logically. The heart wants what it wants.  @joshuaho96 little note for Josh, I run my 525 pump flat out all the time and through the factory lines without any issues. (excluding the melting connectors, that's sorted now. we'll pretend it never happened lol)
    • But the Nexus S3 is very expensive and won't be as purpose-built for the application as a separate electronic boost controller :^) More seriously my pet issue here would be that the Walbro 525 running at 100% duty cycle is going to require more FPR than the stock setup can handle. I'm also pretty sure from what I've seen elsewhere you might want to slow down the pump regardless unless you're going to come up with some way of upsizing the fuel lines coming from the fuel tank. Factory 8mm fuel line doesn't actually flow very much if you want to keep pressure drop down between the fuel pump outlet and FPR. If you really want to "keep it simple" I would run only as much pump as you need and source a fuel pump controller to slow down the pump in the vain hope of being able to run stock-style FPRs which are pretty dinky. Or just use the HICAS lines and it should be mostly fine. OP should also really think hard about what profile they'd want out of the turbo. My pet choice here would be the G1 profile rather than anything higher power but YMMV. I already think ~stock turbo lag is pretty bad so I don't want to make it worse. In "gentle canyon cruising" I found that I spent a lot of time around 4-4.5k RPM. I also recommend DIYing labor if you're detail-oriented enough. Costs are high for labor + if you do it yourself you can be your own quality control.
    • GTSBoy is again on the money. My actual advice? Sell the car. (really). For what it's worth as is, you can sidegrade into something much better. If you care about function then this is the actual move. If you want a Skyline to perform, set aside about $100K to do it. This is NOT a typo. You will see right away these are two very different mindsets. Realistically we're talking full restomod for any Skyline still kicking around. Have an honest think about which one you are.. and what you want to do, and how much you want to invest in this (with no return).
×
×
  • Create New...