Jump to content
SAU Community

Rb25 Over Boost Problem Need Help Asap

lozz_ti

By lozz_ti,
in Engines & Forced Induction

 Share

Recommended Posts

lozz_ti Enthusiast

lozz_ti

Posted
Posted

Hey guys my rb25 is over boosting for some reason on the standard Ecu. It gets to approx 8psi and I can here the gate open then there is a huge flat spot and the boost slowly creeps up to 15psi once it gets to 15psi the flat spot clears out the boost hits 22psi and hits like a early limiter/boost cut.

I fitted my brother's nistune Ecu and the car goes great no flat spot, gate opens at approx 8psi and it makes 9psi tops on my boost gauge. So at this stage I thought the Ecu was stuffed. Got another standard Ecu and fitted it. It was the exact same as my standard Ecu. I have also changed air flow meter and I have replaced the cas. I have run out of ideas as to why it over boosts and has a massive flat spot with two standard Ecu's fitted to it but not with the nistune?

Any body experienced this before? I need to fix this problem asap

Any help would be greatly appreciated!!

Cheers, lozz

lozz_ti Enthusiast

lozz_ti

Posted
  • Author
Posted

Also I disconnected the actuator from the waste gate flap so the gate was open fully open and it was still able to over boost with the standard Ecu. It's really got me confused that it can over boost with the stock Ecu and not with the nistune

Cheers, lozz

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Stock dump? I have only seen this happen with split dumps.

If the engine is going into rich and retard, the extra fuel dumping and timing backed out will help cause the overboost.

GTSBoy Grand Master

GTSBoy

Posted
Posted

Um. Stupidity is happening? Random Chinese turbo + std ECU do not match. If much more airflow is being generated by the turbo than the ECU is happy with, then R&R and other bullshit will occur and happiness will be = zero. Proof of pudding seen by transplanting in Nistune ECU. Get rid of the turbo or get rid of the std ECU.

KiwiRS4T Grand Master

KiwiRS4T

Posted
Posted

Was doing the same thing on standard turbo though? Except not boosting so high but still overboosting. This turbo was said to be direct swap over nothing else needed to be changed.

They lied. You can't tune a stock ecu - get a Nistune chip/
lozz_ti Enthusiast

lozz_ti

Posted
  • Author
Posted

As said it was doing the same thing with the standard turbo but not over boosting as bad. It did have a split dump pipe On it it with the screamer returning back to the exhaust but you could here how loud the car was as soon as the gate opened and there being a massive flat spot it started to sound like a Holden red motor with no exhaust going up a big hill. The standard turbo let go do to over speeding. Put another second hand standard turbo on that the guy promised was mint and the oil seal exhaust side was buggered being the only reason I slapped the Chinese unit On and if I could get it running right I was going to put a decent turbo, Ecu, injector, etc... But really just need it going for now

89CAL Grand Master

89CAL

Posted
Posted

Are you sure there isnt a problem with the wastegate line or a boost tee etc that you dont know about?

A leak in the wastegate line will cause overboosting. If you'r stock turbo blew up due to overboosting and now your still having overboosting problems then I would check there is nothing wrong on the wastegate vac line side of things.

Running the stock ECU with any bigger then stock turbo is still not a good idea. The car will run horribly. Even stock turbo with extra boost can be bad. Mine wouldnt run any more than 8psi with stock ECU, would just hit a massive cut in the tune and the car would jerk and then go again. It also had horribly rich AFR's (10:1)

We aren't trying to make you spend more money. Most of us have all been there trying to get the stock ECU to do something it doesnt want to do. They are usually more forgiving on R32's but still sometimes throw problems up

lozz_ti Enthusiast

lozz_ti

Posted
  • Author
Posted

Thanks for the info guys I ended up buying a the nistune I borrowed. The New turbo came with a new hose it went straight from the compressor housing to the actuator. It really just had me confused that the standard Ecu could make it over boost and build up to 22 psi and the nistune wouldn't build anymore that 8-9 psi

Dose Pipe Sutututu Grand Master

Dose Pipe Sutututu

Posted
Posted

Sounds like timing might be off for whatever reason, like full retarded to build that kind of boost.

Not half retard, full retard lol..

Still doesn't make any sense, but hey your car is running

  • Like 1
Cyifly Community Regular

Cyifly

Posted
Posted

Thanks for the info guys I ended up buying a the nistune I borrowed. The New turbo came with a new hose it went straight from the compressor housing to the actuator. It really just had me confused that the standard Ecu could make it over boost and build up to 22 psi and the nistune wouldn't build anymore that 8-9 psi

There has been a few guys I've neg with standard ecu's runnin 20 - 23 pound boost. Don't ask me how ..

Just happened to be what they were running. They ran rough though apart from wot. Would have gone way better had they spent the money on an ecu

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

    • Steal01
      Torana Lx Gtr Hatch, Lots Of Pictures

      By Steal01 · Posted

      It’s going to be a beast!
    • soviet_merlin
      Stagea Front CV Axle Question

      By soviet_merlin · Posted

      Man, different parts but the same numbers is terrible @dbm7! And it doesn't help that most online shops don't list the part numbers at all. They just give a list of compatible models...
    • MBS206
      R32 GTST - 600KW+ RB28/CD009 Build

      By MBS206 · Posted

      Slow when hot could also be because its getting more dynamic compression, OR things are getting a bit tighter once it is all expanded. If it were an earthing issue, typically I'd expect you to have it have issues all the time. Unless it's really a combination of both things. Where the higher compression, and things being a bit tighter, is giving that bit of extra load and you do need a slight clean up on the cables/connections.
    • dbm7
      Stagea Front CV Axle Question

      By dbm7 · Posted

      Yeah, this is one of the most annoying things about nissan part numbers... I've got an unrelated example... Image is of the AT output shaft ~ they have the same part#, but clearly the shaft on the left is beefier design to that on the right ...the difference (essentially) is the 'lighter' shaft on the right, is for engines up to RB25DE (this includes RB20 variants) : the shaft on the left is for RB25/26DET(T)....are they interchangeable? Yes...but obviously one shaft is going to be stronger than the other...and, the lighter shaft is around USD115, but the heavier shaft closer to USD150...same part#... ...epc-data usually tells a tale ~ the amayama listing for 39100-23U60 has a note "Longest side is between 60 and 105 cm" ; no such info is there for 39100-23U70 ...and given the great disparity in price between the 2 parts, it makes me at least curious (to the point of caution) where the 'extra money' went? ...ie; these 2 parts have a cost difference that (to myself at least) isn't explained by 'plastic boot'...ie; with amayama there's AUD700 price difference ...plastic versus rubber?...I'm not seeing it like that...and 60cm ~ 105cm...??...that's a huge disparity....something hinky going on here... I'd try searching by VIN, not model... /2cents
    • Duncan
      Stagea Front CV Axle Question

      By Duncan · Posted

      I don't know for sure, but I'd expect them all to be interchangeable given the diff end and hub end don't move/change between any C34 series. Often Nissan will change part numbers and the aftermarket follows those year ranges; but the original part number change doesn't mean other parts won't fit. The change could be a change in material, internal parts or even just supplier. For example, all the RB gearbox to engine bolts are no longer available and there is a new part number instead. The only change is they went from cadmium plated bolts to zinc plated due to the issues manufacturing with Cadmium. They look different but work the same.
×
×
  • Create New...