Jump to content
SAU Community

Recommended Posts

hi guys, having a bit of an issue atm with my R34 GTT RB25 NEO. its been rebuilt and currently getting tuned,

the tuner found out the VCT wasn't connected so it is now connected but after 5000rpm it sounds like a valve is hitting the piston.

he heard this and turned the car off right away and D/C the VCT solonoid.

He took apart the timing belt cover and timing perfect and the TB has not jumped any tooths.

All clearances were checked and triple checked before bolting the block to the head.

It only happens when the is VCT activated, anything below 5000RPM, there is no noise and drives perfectly, idles perfect and no stuttering or hesitation.

Can anyone help me with this problem and to sort it out?

My car has been off the road for quite some time and this was suppose to be the final stage but now looks like it could be delayed longer by this unknown noise thats really got me worried :(

If anything, he will end up tuning the car without VCT activated.

Appreciate any feedback or input regarding this situation.

Edited by mill-180

Its probably knocking, if it were a valve hitting a jam pot there would be next to nothing left.

So wait, tuner tuned car with No NVCS then hooked it up and ran it up on the dyno? and it made noises....yup sounds like it was pinging its head off to me.

Also I'd find a new tuner if he didnt re-tune after hooking the vct up.

Even a few taps of piston to valve will bend the valves. If it hasnt been damaged yet then it might not be contacting.

Try turning the vtc on at a lower rpm and see if the noise is still there.

It might be pinging

and for ppl who said it drives crap with VCT turn off, i ran it in for 1000KM with the VCT turned off (i didnt even know it wasnt connected) and the car drove perfectly, no issues or felt "sluggish" at all.

Would a knocking noise be that audible outside the car?

Surely my tuner would know what knocking/pinging sounds like.

It might have driven perfectly without it. But with it it should be even better.

He should know what pinging sounds like. Its hard for us to diagnose sounds. We are just giving possible causes

and for ppl who said it drives crap with VCT turn off, i ran it in for 1000KM with the VCT turned off (i didnt even know it wasnt connected) and the car drove perfectly, no issues or felt "sluggish" at all.

Would a knocking noise be that audible outside the car?

Surely my tuner would know what knocking/pinging sounds like.

well you'll be in for a nice surprise when VCT is turned on and you see the difference.

if you don't, then same as the other thread about it recently - the tuner is doing it wrong.

+1 for it being tune related.

At 5000rpm a valve hitting the piston is not going to end well. Think about human reaction time, it would have hit the piston at least 10 times at those engine speeds before he backed off. If the car drives fine now and es checked everything I don't think this is your problem

If the VCT is being turned off at 5000rpm then your piston to valve clearance gets bigger as the cam is retarding. Try giving it a free rev with it on as - in battery voltage across the two solenoid pins and see if it still makes the noise not under load. Is there any chance that it is PWM the solenoid after 5000rpm - they can be quiet noisy.

hi guys,

thanks for all the replies.

i was reading through this thread,

http://www.skylinesaustralia.com/forums/topic/353835-rb25-hi-flow-turbo-and-vct-help/

and it indicated that the VCT solenoid can be noisy and make clicking noises? it never did this before, is there any reason why it should be noisy now?

I am going to visit the tuner tomorrow and try and hear the sound myself first hand.

He is an experienced tuner so i trust his judgments, hopefully he is right.

I'd hate to find out that it was infact a noisy solenoid and he charged me unnecessary labour to check if the TB was correct.

I'd hate to find out that it was infact a noisy solenoid and he charged me unnecessary labour to check if the TB was correct.

LOL

Are you serious?

He is doing a process of elimination - fact is, that costs money and time.

If you want a proper job, dont be a tightass.

Better to rule something out initially than not at all especially with that type of noise.

You'd cry like a baby if it had smashed all the valves and he said it was just a VCT solenoid now wouldn't you?

Yeah I see what you mean nismoid, but the TB was triple checked before installing cover back on and I was 100% sure it wouldn't of been off. I guess he just wanted to be sure.

Now regarding the noisy solenoid, does anyone have a YouTube link to what it would sound like? Is it common that these would be louder then usual when it was perfectly quiet before?

Zebra; he was tuning for cruise then moved onto WOT and he found out the VCT was d/c so he got it connected, then started to tune again with the VCT that's when the noise occured.

Te solenoid works from 1500-4500rpm, then after it would turn off, if this the case, why wud it get louder after 5000? if it was infect the valve hitting the piston, then the damage wudve already been done and the motor won't even run anymore.

Hu uh a guessing game [claps hands]

a valve guide sliding up and down in the head

sorry for you though, its going to cost $$$ whatever it is..........and it will frustrate the hell out of you until you find it.

BTW I really don't know, without sound and being there its a guessing game.

and for ppl who said it drives crap with VCT turn off, i ran it in for 1000KM with the VCT turned off (i didnt even know it wasnt connected) and the car drove perfectly, no issues or felt "sluggish" at all.

Would a knocking noise be that audible outside the car?

Surely my tuner would know what knocking/pinging sounds like.

VCT makes a huge difference, its like comparing an rb20 to an rb25

I had a similar sound from a motor I built. It was actually the timing belt vibrating and touching the lower timing cover on the side... might be worth a look.

Edited by BoostdR

VCT makes a huge difference, its like comparing an rb20 to an rb25

I used to have mine triggered by a msd digital window sw and tried numerous on/off switchin pts and the difference was verrrrry minimal with the seat of the pants meter....waste of time in my book ......this was on the stock ecu tho, it only decresed spool time by a couple 100rpm

UPDATE:

ok its definitely not a clicking noise from a vct solenoid, sounds like a grinding noise.

the tuner set the vct to kick in earlier @ 2000rpm and thats when the sound occured.

Any ideas people?

If its only when the soleniod is activated then is got to be somthing with the vct mechanism???

When you say rebuilt did you get new pistons? A few people have had problems with the pistons supplied for neo engines and ended up with very high compression ratios suggesting that the pistons were not really suitable.

I used to have mine triggered by a msd digital window sw and tried numerous on/off switchin pts and the difference was verrrrry minimal with the seat of the pants meter....waste of time in my book ......this was on the stock ecu tho, it only decresed spool time by a couple 100rpm

put it on a dyno, the difference is massive.

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

    • Hey lads  so im finally putting together my rb30 forged bottom end and ran into an issue. I measured my main bearing clearance with arp main studs torqued to 60 ft-lbs using ACL H series STD size bearings and standard, un-ground crank shaft journals and got an oil clearance reading of about 1.3 thou measuring straight up and down and about 2.8 thou measuring at a 45 degree angle (just above and below the parting line). My machine shop said they measured the main tunnel and it was all within spec (they didnt say the actual measurement) and to go with a standard size bearing, which i have done and the clearance is too tight, I'm guessing because of the extra clamping force from the arp studs distorting the main tunnel. I was wanting to run about 2.5 thou main bearing clearance.  My questions are: 1. could i just use the HX extra 1 thou clearance ACL bearings? that would fix my straight up and down clearance making it about 2.3 thou, but then would the side to side clearance be too big at around 3.8 thou? 2. what actually is the recommended main bearing clearance for measuring near the parting line / side to side. i know its supposed to be bigger as the bearing has some eccentricity built into it but how much more clearance should there be compared to the straight up and down measurement? at the moment there is about 1.5thou difference, is that acceptable or should it be less? 3. If i took the engine block + girdle back to the machine shop and got them to line bore the main tunnel (like i told them to do the first time, but they said it didnt need it) what bearing size would i buy? the STD size bearing shells already slide in fairly easily with no real resistance, some even falling out if i tip the girdle up-side-down. If im taking material out of the main tunnel would i need a bearing with extra material on the back side to make up for it? this is probably confusing af to read so if something doesn't make sense let me know and ill try explaining in a different way. My machine shop doesn't come back from christmas break until mid January, hence why i'm asking these questions here. TIA for any help or info 
    • I bought the model back in Japan in Feb. I realised I could never build it, looked around for people who could build it, turns out there's some very skilled people out there that will make copies of 1:1 cars or near enough. I'm not really a photo guy... but people were dragging me in a group chat for the choice of bumper as someone else saw the car before it was finished as they are also a customer of that shop. I took the photo in the above post because I was pretty confident that the lip would work wonders for it. Here's some more in-progress and almost-done pics. It gives a good enough idea as to what the rear looks like!   I have also booked in a track day at the end of January. Lets all hope that is nothing but pure fun and games. If it's not pure fun and games, well, I've already got half an engine spare in the cupboard 
    • Well, do ya, punk? Seriously though, let's fu<king go! The colour and kit looks amazing on the car. Do you have any shots from the rear? I don't quite follow how the model came around. You bought the white kit and he modified it to match your car? Looks nuts either way!
    • So my car is finally back from paint! This took an absolutely insane amount of work and should get it's own build thread - but I didn't build it. It was completed by Troy @ https://scalekustoms.com.au/ I originally bought the AOSHIMA URAS Type R kit while I was in Japan, it's supposed to look like this when assembled: Now, I thought that was cool enough until I opened the box with Dismay, as there's no way I could possibly have completed it. The thing is 1/24 and has details down to the steering wheel horn button, which is a 2mm diameter sticker. I originally wondered if someone could make it at all, as is - But then things got a little carried away. It's worth noting that the model does not have an openable bonne, let alone engine bay, OR an openable boot. - Troy has worked wonders with 3D printer and presumably better eyes than I will ever have. My photos suck, so I will post up some of his in-progress ones he sent to me during the way. Unsuprisingly, he is very detailed. A lot of these are out of order. But he: 1) Made a LS engine and an engine bay appear out of thin air 2) Made the bonnet removable 3) Printed the rims I will buy in the future (or any rim you want) 4) Printed and added the wing that is going on 5) Tinted my back windows as this is what my car has IRL (privacy glass) 6) Added a licence plate. 7) Somehow did the interior 8) 3D Printed my actual seats 9) Made the exhaust under the car connect even though this is likely invisible. 10) Created a boot with my fking battery box, power steering reservoir, subwoofer and toolboxes back there. To say it's insane is an understatement. And I f**ked it all up because when I was re-mounting the wing (it broke in transit) I spilled glue everywhere and ripped paint up and Gregged the rear half of the car. Which about makes sense. Also, this arrived on the same day. Quite the change from: I spent 16 hours per day over the next 3 days pre-christmas putting the interior back together, mounting lip, fixing various bodykit problems with window mouldings, etc. and servicing, rebuilding my 370z brakes to go on the car 'soon', messing with heights to check clearances for new wheels, etc. I also had a foray into mounting wiper-mounted washer jets which was an absolute disaster. The bodyshop has welded (and painted) over the stock jet locations for reasons unknown to everybody (i.e they forgot) I also wanted to wire in the oil pressure sensor on Christmas Eve which was a BAD IDEA. You do not know terror like pulling your ECU apart, pinning in half-fitting pins that aren't the right ones, but trying anyway because it's Christmas eve, putting your ECU back together and having a no-start condition with a fuel pump not priming. Then you undo all your work and the fuel pump still doesn't prime. So after all that terror and horror and pain and tedious disassembly, the issue was the relay in the boot which seems to have died/stuck when I was turning the car off and on about 700 times testing shitty washer jets. I also re-wired the fuel pump power plug which fell apart in my hands. I am very happy I had 3 extra pre-made ones from a few posts/last Christmas's breakdown. https://bluewireautomotive.com/products/10-x-pcm-ecm-ecu-terminals I have put an order for these in, so I can actually add the pins to the ECU properly. The commodore ECU does not have the pins for Oil Pressure via ODB2. However the ECU can support it if you create the pins and wire them in. So for round two, and somehow attempting to route that into the engine bay through my impossible engine bay grommet is a fight for another day. It's 40C in Melbourne tomorrow, I am half tempted to drive the car with the aircon on to deliver presents to my partner's family and see if it helps with the overheating-on-40C-days-in-traffic-with-aircon-on-only issue that the vents were intended to solve. Do I feel lucky?
    • Yes, while being... strictly unnecessary. Tuning is a bit like quantum physics. You don't need to understand what Schroedinger's equation actually means. You just need to run the computation and accept the answers. With tuning, you just push page up/down until the exhaust tells you that you've got the fuel right. The VE can stay hidden behind the curtain like the Wizard of Oz and you'll never need to know what he looked like.
×
×
  • Create New...