Jump to content
SAU Community

Rb25det Idle Rev Move Up And Down :(

perzn_34

By perzn_34,
in Engines & Forced Induction

 Share

Recommended Posts

perzn_34 Experienced

perzn_34

Posted
Posted

Hey guys i have a r33 rb25det motor in my r34 gtt. Its a build motor has been in there almost a year and it has always been fine.

I have a td06h 25g setup putting out 322rwkw on 20PSI with haltech p1000. I run a Greddy copy inlet plenum with a BM 80m throttle body.

Recently i changed my wastegate to a new turbosmart. I got confused with which hoses goes to the top of the gate and whiten goes to the bottom of the gate, a few trial and error caused a few runs down the freeway over boosting to about 30psi maybe a bit more.

I have fixed the issue of overboosting but now it idles at 1400rpm to 1800rpm, and once the engine is WARM the idle bounces between 1400 to 1900rpm, up and down.. all the time once warm. Driving and boosting is fine.

I thought maybe I'm leaking air, or blew hoses off, but i checked them all and seem to be fine. Also had a look at the inlet manifold gasket up close with a torch and the didn't seem like any pieces of it has blown out. i can see the gasket also has silicon on it too.

SO can anyone tell me whats the cause of the high idle rpm and the revs bouncing???

Any help would be greatly appreciated thanks

Link to comment
https://www.sau.com.au/forums/topic/457712-rb25det-idle-rev-move-up-and-down/
Share on other sites
scotty nm35 Grand Master

scotty nm35

Posted
Posted

30psi sounds good Andrew. Why were you trying to fix it? :P

Sounds like there is a leak as I said, causing the idle air control valve to open and close while trying to lower the idle to it's preset revs.

If there are no visible leaks, a pressure test may be the best option...

Blackkers Experienced

Blackkers

Posted
Posted

While it's idling you can spray some throttle body cleaner or degreaser or wd40 on the suspect areas and listen to the idle.

It just helps to rule out things like gaskets which are hard to visually diagnose

perzn_34 Experienced

perzn_34

Posted
  • Author
Posted

I did spray some degreaser on the inlet plenum gasket and the revs droped a bit like its going to stall. It was along the whole gasket. So could it be the whole gasket leaking? :s

Also what replacement gasket should i use? What silicon? And should u machine the freking greedy fake manifold? Its like $200 to machine them ffs

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

    • DraftySquash
      Help Understand GTT Boost Setup

      By DraftySquash · Posted

      Me, if I ever floor the car
    • Kinkstaah
      Help Understand GTT Boost Setup

      By Kinkstaah · Posted

      You have the option to do this. Nobody but me ever did this (go slower, I mean) Everyone seems to fall victim to "This would be a great setup for you, but for me, I need a little more power..."
    • joshuaho96
      Help Understand GTT Boost Setup

      By joshuaho96 · Posted

      Save yourself the headache of an alarm. Immobilizer on the signal side of the main EFI relays so it won't start is good enough. DIY killswitch is the same thing except instead of a nice passive system you need to remember to switch it on and off.
    • GTSBoy
      Help Understand GTT Boost Setup

      By GTSBoy · Posted

      Yeah, the advent of canbus was supposed to cut down on wiring weight, then some bright marketing wonk says "oh, look at all these wonderful tech gadgets we can cram in here now that we have this wonderous technology" and some arsehole safety legislator says "oh, look at all the wonderful surveillance and tracking gadgets we can cram in here now that we have this wonderous technology" and some dipshit young engineer who has grown up thinking that an extra 500000 lines of code is not a problem because storage is cheap these days says "oh look at all this wonderful shit I can do to one up those dipshit arsholes over at VW" and the Karens of the world all go "oh look at all these fancy things I can do on my screen (so long as I am not driving on a bumpy road wherein touch screens immediately become the single most stupid shit idea ever shoveled into a car) and my 19 zone airconditioning keeps my sweaty fat folds a bit less damp and the windows close themselves because I'm too fat and lazy to wind them up for myself and these reversing sensors would have been great if I'd paid attention to them instead of smashing them on the bollard while I was reversing and staring fixedly forward that day I went to pick up little Charlize from ballet" and the sweaty mongoloids who say "oh this wonderful collision avoidance technology with these 45 excellent radar antennae scattered across the front of my car mean I can tailgate like a methed up tradie at full speed with no fear because the car and the 35 airbags will protect me if it all goes wrong" ...... </shallistopranting?>
    • Dose Pipe Sutututu
      Help Understand GTT Boost Setup

      By Dose Pipe Sutututu · Posted

      There's a post from a member (can't recall who), went down the path of a twin scroll G30-660 and it's doing over 300kW+ AND comes on about the same as a high flow RB25DET turbo. Have your cake and eat it too in this case. TBH, if I had a 2nd chance of building my car again (i.e. someone gave me what I wanted for my shit box, but the deal was I had to re-build another R33 and keep the change) I would just pop in a stock NEO motor (with new seals, rod bearings, ARP studs, head gasket, sump, Nitto pump), get a smaller twin scroll turbo, modify the stock low mount (keep the divider in place), and make a solid 300kW on 98RON and call it a day. 
×
×
  • Create New...