Jump to content
SAU Community

Rb25 Cold Start Valve Clean

HR32GTS 4DOOR

By HR32GTS 4DOOR,
in Tutorials / DIY / FAQ

 Share

Recommended Posts

HR32GTS 4DOOR Community Regular

HR32GTS 4DOOR

Posted
Posted

So after having problems starting my car without any throttle ever since the engine swap I decided to do something about it.

Also since I couldn't find a tute on here so decided to document the process.

Disclaimer

Attempt this at your own risk. I am neither an auto electrician nor a mechanic. I take no responsibility for any damage that you do to your vehicle in the process of following this guide.

Difficulty - Easy

Time taken 30-45 min

Things you will need

Flat head pliers

10mm socket with 1/2" drive ratchet and extension

phillips head screwdriver

Carby cleaner

A band aid

Directions

The valve on an RB25 is located under the plenum, on an RB20 is is under the throttle body.

locate the valve it is a metal and black thing with two vacuum hoses attached to each end.

This is what it looks like under the plenum with one of the vacuum hoses disconnected.

post-80155-0-55159500-1349257506_thumb.jpg

Use your pliers to remove the clamp and then gently pull the hose off (where it would be in the above picture). The hoses are old and may be quite brittle so take care in removing them.

Then there are two 10mm bolts holding the valve to the bottom of the plenum, use your ratchet and extension to make it a lot easier to access.

after the bolts are out take off the clamp on the other hose and pull the valve from the hose. Again carefully.

Once you have the valve out it should look like this.

post-80155-0-06991300-1349258058_thumb.jpg

there are four screws holding the black plastic part on. undo these and it should look like this. make sure you dont damage the gasket as this will cause a boost leak if not rectified.

post-80155-0-68619800-1349258173_thumb.jpg

I didn't take the valve appart any further as I didn't think it was necessary.

from here spray both parts with carby cleaner, it will probably be all gummed up with oil like mine was so take your time and it should all come up good.

Final result.

post-80155-0-09504000-1349258387_thumb.jpg

Then just do the opposite to put it all back together, also make sure you do up the four screws nice and tight you don't want to have to pull it back off because its leaking.

Link to comment
https://www.sau.com.au/forums/topic/410701-rb25-cold-start-valve-clean/
Share on other sites
  • 1 month later...
HR32GTS 4DOOR Community Regular

HR32GTS 4DOOR

Posted
  • Author
Posted

Hey, was your cold start valve plugged in? I've got a RB25 in a R32 that has custom wiring so I'm not sure if there is or isn't a plug for it.

Yeah mine was plugged in. I did the wiring for this engine myself out of an rb20 loom. The plug is a purple/blue plug looks limilar to a side feed injector plug.

HR32GTS 4DOOR Community Regular

HR32GTS 4DOOR

Posted
  • Author
Posted

Hey, I found a purple/orange plug underneath the throttle body, so I feed it in between the intake runners and it plugs in to the cold start valve. Will the wiring melt if I leave it like this?

This is how I have mine plugged in, going in between the runners. I haven't had mine melt and I doubt the plenum would get hot enough to do any damage. If it did id say you would have a lot more to worry about.

  • 5 months later...
Tommmay Enthusiast

Tommmay

Posted
Posted

Its under the plenum and above the oil filter. Idle would not really be changed if you didn't have one unless it's just been removed and the vacuum lines were just left there.

Ahhh its there dont know how i missed it

What i meant by that idle comment is when its cold it needs throttle to start/idle after that it seems to idle good

  • Like 1
HR32GTS 4DOOR Community Regular

HR32GTS 4DOOR

Posted
  • Author
Posted

Just done my one and it looked brand new inside lol

could the actual mechanism be faulty?

It could be, but its pretty simple so it's not all that likely wiring could be stuffed also. when you start your car for the first time does the idle sit a little higher than when warm like at 1500-2000 rpm? or does it just idle at same rpm as when warm?

Tommmay Enthusiast

Tommmay

Posted
Posted (edited)

It could be, but its pretty simple so it's not all that likely wiring could be stuffed also. when you start your car for the first time does the idle sit a little higher than when warm like at 1500-2000 rpm? or does it just idle at same rpm as when warm?

Pretty sure it idles at the same rpm and will not start without a squirt or 2 of throttle

Sucks cause there is not much information about this issue

Edited by Tommmay
HR32GTS 4DOOR Community Regular

HR32GTS 4DOOR

Posted
  • Author
Posted

Ok if it idles at the same rpm there is either something wrong with the valve or it isn't being switched by the ecu (more so a wiring problem) unfortunately I don't know how to test the valve to see if it works. Could check if there is continuity between ecu out and the plug for the valve (will have to look up a pin out diagram for the ecu to find which pin) this will tell you if it is a wiring problem or something else. Could also try another valve, I doubt it would be very expensive from a wrecker

Tommmay Enthusiast

Tommmay

Posted
Posted

Ok if it idles at the same rpm there is either something wrong with the valve or it isn't being switched by the ecu (more so a wiring problem) unfortunately I don't know how to test the valve to see if it works. Could check if there is continuity between ecu out and the plug for the valve (will have to look up a pin out diagram for the ecu to find which pin) this will tell you if it is a wiring problem or something else. Could also try another valve, I doubt it would be very expensive from a wrecker

There is continuity in the plug but who knows how it works without a wiring diagram

Ill just take it in the ass rev it every morning lol

HR32GTS 4DOOR Community Regular

HR32GTS 4DOOR

Posted
  • Author
Posted

I'm not sure but I would assume when you valve is powered (ie when the ecu thinks its cold enough to need it) the valve would be open, so when its appart it would be closed as its not powered. The needing throttle to start can be caused by a few things like vacuum leaks, fuel pump not priming properly etc. If it needs throttle to start when the car is warm then this is not your problem.

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
 Share
Go to topic listing


  • Similar Content

  • Latest Posts

    • EndZee
      R33 Gts/-t Abs Module Wiring Schematic (not Gt-r)

      By EndZee · Posted

      Brooooo Please send ABS control unit schematic Please! R33 gts25t ABS (Its two plug ecu, black and white) wire colors possible? [email protected]
    • GTSBoy
      Boost cut after swap(RB25DET NEO) R34

      By GTSBoy · Posted

      Don't even try to run it on the stock ECU if you're going to have the boost controller bring boost above ~10 psi. I've already told you that. If you use the Nistune ECU, you will need to CAREFULLY read the available documentation for Neo tuning, and read some threads on the Nistune forums, to discover the various things you have to do to prevent the ECU from going bananas when the boost is too high. The is a table associated with th boost sensor that must be modified to prevent it from shitting the bed. This is just one of the things that you will need to do to the tune in Nistune, because the Neo turbo ECU will be expecting to see a number of things (such as the TCS) that are not there, and you have to block the DTCs on those. It is totally not surprising to me that you are having the problems that you are, but the solutions to these problems have been known for >15 years. So just get it done.
    • dyl33
      VOLK RACING GTC CENTRE CAPS

      By dyl33 · Posted

      Centre caps $250
    • Kapr
      Boost cut after swap(RB25DET NEO) R34

      By Kapr · Posted

      Hi. Sry iam not a mechanic and iam not at the car atm so i dont know 100% but they told they measure those and even try to change those. AFM they have two. Coils are new a they have my old one too. Plugs too. ECU...we have 25 NEO stock and Nistune 25 NEO.   But i dont know if any one those could be the problem and why/if/what can cause this, Only thing they did not check is fuel...but that walbro 255 is new(like 1,5 years)... That fuel pressure gauge idk...but i let them know Any suggestions?   EDIT: how can they know if it is like you say he ECU pull power when it reaches a specific boost level that is too high? Tha car has boost controler
    • Duncan
      Boost cut after swap(RB25DET NEO) R34

      By Duncan · Posted

      Can you clarify what you mean by boost cut, do you mean it misfires both when under load (driving) and when stationary and out of gear? Or does the ECU pull power when it reaches a specific boost level that is too high (boost control issue)? Does it occur at idle with no throttle? When you say "the ECU is OK", what ECU is it and why do you think it is OK? Have you used the NEO ECU, and if so do you have a MAP sensor attached? Same for the AFM, why do you think it is OK? Do you have any way to put a fuel pressure gauge on it (even just a mechanical one between the fuel filter and fuel rail)?
×
×
  • Create New...