Jump to content
SAU Community

Rb25 Stalling Momentarily

Marcus89

By Marcus89,
in Engines & Forced Induction

 Share

Recommended Posts

Marcus89 Proficient

Marcus89

Posted
Posted

My r34 rb25det neo has decided to develop a strange issue where I will be drifting and when I shift gears from 2nd to 3rd mid drift it will stall out just for a second causing it to bog down. Initially it happened rarely at the start of the night but got progressively worst as the night went on. It got the to point where clutch kicking it in 3rd (after having shifted 2nd to 3rd and had the stall out) would cause the same issue to happen again rather than for the car to start hooking up like it had done earlier in the night. I went to pits to try and find any potential air leaks or something along those lines but could not find anything and the car idles perfectly beautifully does not hunt. After being in pit for about 10 mins took it out for a run and it seemed to have no issue at all. Went for another go and the issue was back again.

Whenever I drove normally ringing out 1st, 2nd and 3rd gear there was no noticeable issue it only presented when I was drifting.

Engine mods are as follows:
Nistune
3inch turbo back exhaust
Hypergear g2.5
Bosch 550cc injectors
Oil cooler
FMIC
52mm Alum rad
Bosch 023 fuel pump
Still running recirculating BOV

I feel a likely culprit could be the fuel pump being on its way out. Does anyone think a fuel pump that's starting to run out of steam would present with these kind of issues?

Another option I was thinking was that my recirculating BOV could be leaking air out as some of the piping is a bit average and this could be a big enough difference for it to confuse the ECU as it doesn't see the air that it expected to be there.

I really wish the issue was something more obvious/severe as it seems so vague I don't really know where to start and unfortunately don't have the money to just start changing everything (crap job and going back to uni). In the end it is my daily and still drives perfect for daily duties at least at current.

Link to comment
https://www.sau.com.au/forums/topic/444378-rb25-stalling-momentarily/
Share on other sites
robjen Rookie

robjen

Posted
Posted

Might be completely off track here but a log truck I was driving did this cut out thing. It was too quick to log a fault code so after 12 months of looking poking, trying and several trips to cummins and brown and hurley and anyone else who might know something it ended up being the fuse holder in the battery box. Pliers on the fuse holder, squeeze, insert fuse, never another problem. Maybe not the problem but I always start by shaking fuses.

Ben C34 Grand Master

Ben C34

Posted
Posted

Does it come off boost with gear changes and is the rpm around the 3k mark, if so the mixture could be leaning out slightly when you come back on throttle. Just a thought.

Is that based on something?

If the ecu Is tuned correctly there won't be any weird lean spots.

Ben C34 Grand Master

Ben C34

Posted
Posted

Unless something is not doing/ or can't do what it is being told to do.

Of course.

I just wondered because you were specific with the 3000rpms I thought perhaps you had experienced or heard about something .

XGTRX Veteran

XGTRX

Posted
Posted (edited)

Of course.

I just wondered because you were specific with the 3000rpms I thought perhaps you had experienced or heard about something .

Just mentioned it because especially in the OP's description it seems to be happening at a point where it may be transitioning off boost to on boost where if things aren't spot on a temporary lean condition may occur which is consistent with the occurrences the OP is describing. Just a suggestion anyway.

Oh and a guy with a 200 that was street driven had to add a heap of fuel in this transition area when he started drifting but it couldnt be done on the dyno, had to be done on the street.

Edited by XGTRX
Ben C34 Grand Master

Ben C34

Posted
Posted

Really it could be anything.

It could be reversion in the maf causing a rich conditon.

They are fussy when it comes to how the bov is plumbed back to the inlet.

Mine carries on a bit sometimes due to this, but being an auto doesn't cause problems and doesnt happen often. I am going to change the angle the bov return is attached to the inlet pipe to make it point as much towards the turbo autos possible.

Trex Grand Master

Trex

Posted
Posted

How much fuel did you have?

I had this problem when the filter at the end of the fuel pump was a tiny bit higher than stock, it would get worse the lower the fuel got.

skylines and stageas suffer from a lack of fuel when throwing them around. May need a surge tank?

rondofj Veteran

rondofj

Posted
Posted (edited)

I have a 34gtt that does this on downshifts and especially under load, it bogs down for 3-4 seconds and loses 60% of power or even more, its that bad. I have recently found it sometimes does this on up shifts as well but only under load when shifting a bit early up an incline etc. My tuner found the map tracer cell in my power fc jumps 5 cells when it does this, pinpointing to a high voltage drop in my z32 which is possibly measuring more air from b.o.v. reversion n causing the ecu to retard timing n add more fuel. He said it is most likely my bov angle pipe causing afm reversion- not an ideal entry angle- see pic

post-49401-14028386776606_thumb.jpg

Edited by rondofj
Marcus89 Proficient

Marcus89

Posted
  • Author
Posted

Cheers for the tips guys. I was thinking of BOV reversion being a potential issue rondofj I guess the easiest way to suss that out would be on a dyno although seems a bit strange it only really does it when I am sliding. I have put the BOV return pretty far down the intake pipe but it doesn't point that much towards turbo which isn't good.

I don't think it is fuel surge as I feel it would be even worst when transitioning back the other way and not just grabbing a higher gear while maintaining the same slide which doesn't really slosh the fuel around much.

I've started to think it may actually be a small intake leak that opens up more on boost causing the car to run real rich on boost (Will be doing a intake pressure test soon as it's easy and free)

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

    • Kapr
      "Cheap" bolt on turbo on RB25DET NEO

      By Kapr · Posted

      You are selling this? I have never bought something from marketplace...i dont know if i trust that enough. And the price is little bit "too" good...
    • Watermouse
      "Cheap" bolt on turbo on RB25DET NEO

      By Watermouse · Posted

      https://www.facebook.com/share/19kSVAc4tc/?mibextid=wwXIfr
    • Kinkstaah
      Airbox for +T

      By Kinkstaah · Posted

      It would be well worth deciding where you want to go and what you care about. Reliability of everything in a 34 drops MASSIVELY above the 300kw mark. Keeping everything going great at beyond that value will cost ten times the $. Clutches become shit, gearboxes (and engines/bottom ends) become consumable, traction becomes crap. The good news is looking legalish/actually being legal is slighly under the 300kw mark. I would make the assumption you want to ditch the stock plenum too and want to go a front facing unit of some description due to the cross flow. Do the bends on a return flow hurt? Not really. A couple of bends do make a difference but not nearly as much in a forced induction situation. Add 1psi of boost to overcome it. Nobody has ever gone and done a track session monitoring IAT then done a different session on a different intercooler and monitored IAT to see the difference here. All of the benefits here are likely in the "My engine is a forged consumable that I drive once a year because it needs a rebuild every year which takes 9 months of the year to complete" territory. It would be well worth deciding where you want to go and what you care about with this car.
    • GTSBoy
      Airbox for +T

      By GTSBoy · Posted

      By "reverse flow", do you mean "return flow"? Being the IC having a return pipe back behind the bumper reo, or similar? If so... I am currently making ~250 rwkW on a Neo at ~17-18 psi. With a return flow. There's nothing to indicate that it is costing me a lot of power at this level, and I would be surprised if I could not push it harder. True, I have not measured pressure drop across it or IAT changes, but the car does not seem upset about it in any way. I won't be bothering to look into it unless it starts giving trouble or doesn't respond to boost increases when I next put it on the dyno. FWIW, it was tuned with the boost controller off, so achieving ~15-16 psi on the wastegate spring alone, and it is noticeably quicker with the boost controller on and yielding a couple of extra pounds. Hence why I think it is doing OK. So, no, I would not arbitrarily say that return flows are restrictive. Yes, they are certainly restrictive if you're aiming for higher power levels. But I also think that the happy place for a street car is <300 rwkW anyway, so I'm not going to be aiming for power levels that would require me to change the inlet pipework. My car looks very stock, even though everything is different. The turbo and inlet pipes all look stock and run in the stock locations, The airbox looks stock (apart from the inlet being opened up). The turbo looks stock, because it's in the stock location, is the stock housings and can't really be seen anyway. It makes enough power to be good to drive, but won't raise eyebrows if I ever f**k up enough for the cops to lift the bonnet.
    • BuiltNotBought
      Airbox for +T

      By BuiltNotBought · Posted

      There is a guy who said he can weld me piping without having to cut chassis, maybe I do that ? Or do I just go reverse flow but isn’t reverse flow very limited once again? 
×
×
  • Create New...