Jump to content
SAU Community

Recommended Posts

Hi Guys,

Changed the stock turbo on my rb20 yesterday for a s2 rb25 one and it wont make any boost at all.

Drives fine off boost and as soon as you get into positive pressure its shudders really bad and wont go past 0.

Car is also Idling abit high (intercooler piping leak?) but this shouldnt cause it to not build boost?

Any help would be muchly appreciated!

Did you leave a rag in the intercooler pipe work???

It's allright... everyone dose it.

No rags in the piping lol. Any other ideas of what It could be?

What about the nipple for the actuator? I drilled and tapped it into the elbow this should be fine yeah?

Not really looking forward to pulling It all apart again lol :)

by any chance you did spin the shaft and stuff making sure both sides of it spin right lol, like u havent shit an exhaust wheel without knowing it have you haha

other than that look for big leaks, but somehow i doubt it.. based on the offboost drivability i mean

Car is also Idling abit high (intercooler piping leak?) but this shouldnt cause it to not build boost?

Are you saying that you suspect an intercooler pipe leak, but that an intercooler pipe leak wont stop the car building boost? Because it will - the boost will leak out!

Are you getting black smoke out the back? If you have a boost leak it will run very rich and you'll get black smoke. Perhaps so rich that missfires/shudders.

If its not a boost leak check that the wastegate isnt stuck open (you should be able to move the actuator rod with your hand, or just apply 10psi air pressure to it and watch it move). But i dont think your symptoms match a stuck wastegate.

Are you saying that you suspect an intercooler pipe leak, but that an intercooler pipe leak wont stop the car building boost? Because it will - the boost will leak out!

Are you getting black smoke out the back? If you have a boost leak it will run very rich and you'll get black smoke. Perhaps so rich that missfires/shudders.

If its not a boost leak check that the wastegate isnt stuck open (you should be able to move the actuator rod with your hand, or just apply 10psi air pressure to it and watch it move). But i dont think your symptoms match a stuck wastegate.

Thanks for the help MrKotter, I did get abit of black smoke out the exhaust when I first started it and it did feel like it was missfiring but really violently much more so than when my coilpacks died.

And I cant seem to move the actuator rod at all but the flap is closed not open?

Thanks again for your help mate!

Oh and also to everyone else, yes the exhaust wheel is still there and spins freely

Thanks for the help MrKotter, I did get abit of black smoke out the exhaust when I first started it and it did feel like it was missfiring but really violently much more so than when my coilpacks died.

And I cant seem to move the actuator rod at all but the flap is closed not open?

It will be very stuff to move by hand, maybe too stiff. And the actuator pushes on it to open the WG, so you need to try to move it in the same direction. But yeah, its almost certainly not stuck open if you're using the stock dump, and if it was you probably wouldnt be able to move it by hand anyway......so keep looking for the leak. Are you sure your new boost nipple is airtight?

Thanks for the help MrKotter, I did get abit of black smoke out the exhaust when I first started it and it did feel like it was missfiring but really violently much more so than when my coilpacks died.

A boost leak is a much more violent miss fire and cut, as the car is reading that it has 3 times as much air going in as really is, so it throws in 3 times as much fuel as needed, affectively flooding the motor.

A boost leak is a much more violent miss fire and cut, as the car is reading that it has 3 times as much air going in as really is, so it throws in 3 times as much fuel as needed, affectively flooding the motor.

Cheers guys, looks like I'm definately looking for a boost leak then, thanks for the help everyone.

Will report back once fixed.

Hi Guys,

So I took everything apart and put it all back together again, started her up and she seemed fine idle better than last time and much lower too (bout 900).

took it for a drive up the street and when I stopped at the intersection and put it in neutral the car revved by it self upto about 5-6k almost like the throttle was stuck open?

popped bonnet and checked throttle cable and it seemed to be fine, so I started it back up again and managed to put it into gear and it stopped freerevving and I babied it home.

WTF is going on? more boost leaks? didnt get it up to temp so I havent tried to get boost yet.

Thanks guys, this is driving me crazy :)

edit: Just started it up again in the garage and its idling really high again, whats the best way to find the boost leak? soapy water around the silicon bends?

Edited by Jden

Manifold leaking? The problem is after the throttle body I would say, a gasket probably need to be replaced. You can try spraying around the area with carb cleaner to find the leak.

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

    • Update 3: Hi all It's been a while. Quite a lot of things happened in the meantime, among other things the car is (almost) back together and ready to be started again. Things that I fixed or changed: Full turbo removal, fitting back the OEM turbo oil hardlines. Had to do quite a bit of research and parts shopping to get every last piece that I need and make it work with the GT2860 turbos, but it does work and is not hard to do. Proves that the previous owner(s) just did not want to. While I was there I set the preload for the wastegates to 0,9bar to hopefully make it easier for the tuner to hit the 370hp I need for the legal inspections that will follow later on. Boost can always go up if necessary. Fitted a AN10 line from the catch can to the intake hose to make the catchcan and hopefully the cam covers a slight vacuum to have less restrictive oil returns from the head and not have mud build up as harshly in the lines and catch can. Removed the entire front interior just shy of the dashboard itself to clean up some of the absolutely horrendous wiring, (hopefully) fix the bumpy tacho and put in LED bulbs while I was there. Also put in bulbs where there was none before, like the airbag one. I also used that chance to remove the LED rpm gauge on the steering column, which was also wired in absolute horror show fashion. Moved the 4in1 Prosport gauge from sitting in front of the OEM oil pressure gauge to the center console vents, I used a 3D printed vent piece to hold that gauge there. The HKB steering wheel boss was likely on incorrectly as I sometimes noticed the indicator reset being uneven for left vs. right. In the meantime also installed an airbag delete resistor, as one should. Installed Cube Speed premium short shifter. Feels pretty nice, hope it'll work great too when I actually get to drive. Also put on a fancy Dragon Ball shift knob, cause why not. My buddy was kind enough to weld the rust hole in the back, it was basically rusted through in the lowermost corner of the passenger side trunk area where the wheel arch, trunk panel and rear quarter all meet. Obviously there is still a lot of crustiness in various areas but as long as it's not rusted out I'll just treat and isolate the corrosion and pretend it's not there. Also had to put down a new ground wire for the rear subframe as the original one was BARELY there. Probably a bit controversial depending on who you ask about this... but I ended up just covering the crack in the side of the engine block, the one above the oil feed, with JB Weld. I used a generous amount and roughed up the whole area with a Dremel before, so I hope this will hold the coolant where it should be for the foreseeable future. Did a cam cover gasket job as the half moons were a bit leaky, and there too one could see the people who worked on this car before me were absolute tools. The same half moons were probably used like 3 times without even cleaning the old RTV off. Dremeled out the inside of the flange where the turbine housing mates onto the exhaust manifolds so the diameter matches, as the OEM exhaust manifolds are even narrower than the turbine housings as we all know. Even if this doesn't do much, I had them out anyways, so can't harm. Ideally one would port-match both the turbo and the manifold to the gasket size but I really didn't feel up to disassembling the turbine housings. Wrapped turbo outlet dumps in heat wrap band. Will do the frontpipe again as well as now the oil leak which promted me to tear apart half the engine in the first place is hopefully fixed. Fitted an ATI super damper to get rid of the worn old harmonic balancer. Surely one of the easiest and most worth to do mods. But torquing that ARP bolt to spec was a bitch without being able to lock the flywheel. Did some minor adjustments in the ECU tables to change some things I didn't like, like the launch control that was ALWAYS active. Treated rusty spots and surface corrosion on places I could get to and on many spots under the car, not pretty or ideal but good enough for now. Removed the N1 rear spats and the carbon surrounding for the tailpipe to put them back on with new adhesive as the old one was lifting in many spots, not pretty. Took out the passenger rear lamp housing... what do you know. Amateur work screwed me again here as they were glued in hard and removing it took a lot of force, so I broke one of the housing bolts off. And when removing the adhesive from the chassis the paint came right off too. Thankfully all the damaged area won't be visible later, but whoever did the very limited bodywork on this car needs to have their limbs chopped off piece by piece.   Quite a list if I do say so myself, but a lot of time was spent just discovering new shit that is wrong with the car and finding a solution or parts to fix it. My last problem that I now have the headache of dealing with is that the exhaust studs on the turbo outlets are M10x1.25 threaded, but the previous owner already put on regular M10 nuts so the threads are... weird. I only found this out the hard way. So now I will just try if I can in any way fit the front pipe regardless, if not I'll have to redo the studs with the turbos installed. Lesson learned for the future: Redo ALL studs you put your hands on, especially if they are old and the previous owners were inept maniacs. Thanks for reading if you did, will update when the engine runs again. Hope nothing breaks or leaks and I can do a test drive.
    • No those pads are DBA too  but they have colors too. I look at the and imo the green "street" are the best.
    • I’m not sure what happened I told them about sonic tunes free OTS tune and the next the I know .. I was booted..   To funny 
    • Yea - I mean I've seen my fuel pump which is decades old and uh, while I'm not saying this with real knowledge... but I sure get the ick at using anything in the fuel system that produced the state of that pump. Many years ago I went through multiple pumps (and strainers) before I dropped the tank to clean it out with extreme violence. I'm talking the car would do maybe 50km before coming to a halt, which resulted in me cleaning out the filter with some brake cleaner and going on my way. None of my stuff ever looked like what came out of your fuel tank. I don't think I'd be happy with it unless every single component was replaced (or at least checked/cleaned/confirmed to be clean here).
×
×
  • Create New...