Jump to content
SAU Community

RB25 heartbreak HELP PLEASE

97'240sxSE
 Share

Recommended Posts

97'240sxSE Rookie

97'240sxSE

Posted
Posted

Hello I live in the US I have an RB25det and i need to know if anyone has had a problem similar to mine so i can find a direction to start. The RB motor is not reving past 3000 rpm. It pulls hard until it hits that mark then it dies off. It doesnt die it just stops building boost. Ive check the obvious IE boost piping, maf, and waste gate i was wondering if any has had a similar problem.

Link to comment
https://www.sau.com.au/forums/topic/46263-rb25-heartbreak-help-please/
Share on other sites
B-Man Grand Master

B-Man

Posted
Posted

Sounds like some restriction (either phsical or electronic) on the exhaust or the intake.

Check the cat converter & exhaust system (drop the exhaust from the turbo and take it for a spin)

Check that you MAF is working and is wored corretly

Are you running heaps of boost ?? Might be boost cutout from the std ECU ??

Like Sumo said - could be heaps of things - give us more info.,

EVL-180 Apprentice

EVL-180

Posted
Posted

i have a RB 20 in my 180sx wich is the same as your 240sx just rwd apparntly (not sure if your 240 is rwd or fwd???) i found in my car that even with the A31 saffero dash (thats were i got my engine from) the revs still drop off at about 4 grand and it is a little slow gettin up there i have tried a couple of other dashes but apparntly the only way i can fix my problem is by gettin a monter tacho or somethin like that which sux

B-Man Grand Master

B-Man

Posted
Posted
i have a RB 20 in my 180sx wich is the same as your 240sx just rwd apparntly (not sure if your 240 is rwd or fwd???) i found in my car that even with the A31 saffero dash (thats were i got my engine from) the revs still drop off at about 4 grand and it is a little slow gettin up there i have tried a couple of other dashes but apparntly the only way i can fix my problem is by gettin a monter tacho or somethin like that which sux

That sounds a bit weird - how can your dash/tacho cause RPM drop off at 4K ??? WHat happens if you disconnect your tach ??? The car doesn't work ?? I think someone is yanking your chain.......

EVL-180 Apprentice

EVL-180

Posted
Posted
That sounds a bit weird - how can your dash/tacho cause RPM drop off at 4K ??? WHat happens if you disconnect your tach ??? The car doesn't work ?? I think someone is yanking your chain.......

nu thats just what i have noticed in my car its really weird my car still runs fine but the tacho just stops at 4000rpm but it takes ages to get up there.

97'240sxSE Rookie

97'240sxSE

Posted
  • Author
Posted

Ok the wiring is fine and the mass air is new. OO and by the way a 240sx here in the states is just an s13 or s14 chasis (silvia in other words only we get the pitiful ka24de for an engine.) I havent checked the cas sooo that can be a start. The car runs the stock ecu stock boost stock waste gate stock everything NO MODS yet.... I'm trying to avoid running an AFC for the time bieng so any advice would be grand.

THanks from the states

EVeret

paulr33 Grand Master

paulr33

Posted
Posted

it sounds like the ecu is in limp home mode, wont rev past 2500rpm.

this is usually caused by dead or damaged air flow meter.

see if you can swap it with someone else that has an rb25det

failing that build yourself a consult interface or order one and do a diag on it, or do manual ecu diag which can be found on this site somewhere

r33skylinegtst Mentor

r33skylinegtst

Posted
Posted

FWD? ok...ah... why the hell did nissan do that? They took a good car and... crappified it...:)

Sorry, don't mean that in a bad way, just that i find it rather stupid to change a car that was good in the first place. Anyways, good luck with it mate, you chose a good engine for the conversion :wassup:

:D

97'240sxSE Rookie

97'240sxSE

Posted
  • Author
Posted

No the 240sx is RWD its exactly the same as a 180sx but we have the nissan frontier truck motor. Its still rwd. Its just called a 240sx because we got the 2.4L instead of the ca18det or the sr20det. AND you still can drift the crap out of it. i only wish that we got the skyline

tastyratz Apprentice

tastyratz

Posted
Posted

dont you mean ff instead of fr? :(

yea dude ive been told before that the rb25det has the same maf as a 300zx (fairlady z) but DONT QUOTE ME ON THIS. its very possible im wrong but its not a bad direction to research in for a replacement, thats an easier afm to find over here in the states. you could always do the afm correction and make this an excuse to get a q45 afm :)

NewKleer Mentor

NewKleer

Posted
Posted

is ur afm hooked up right? try unplugging it and going for a drive. not sure if that can do any damage, if u think it might, then try:

turn car off. remove hardness from afm. turn key to on (dont think u need to start it), measure voltage between pin 3 (middle pin of the 5?) and negative terminal/earth. if 0v then no power getting to it.

if thats ok, and u can be bothered getting to the ecu:

turn car off, test continuity between pin 4 (when holding harness with connector stub facing upwards, its the 2nd pin from left i think) and ECU pin 26

if thats ok, test continuity between pin 2 and ECU pin 27

finally u can test voltage when car is idling between pin 27 and earth. should be ~1.1v

pin 26 and 27 are the 6th and 7th pin in the top row, counting right from the middle screw thing when the ecu is lying flat (not sure which is top/bottom, try both if ur not sure :rolleyes:

problem may be wiring rather than a stuffed afm

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

    • The Bogan
      NC MX5

      By The Bogan · Posted

      Yeah, it's getting like that, my daughter is coming over on Thursday to help me remove the bonnet so I can install the Carbuilders underbonnet stuff,  I might get her to give me a hand and remove the hardtop, maybe, because on really hot days the detachable hardtop helps the aircon keep the interior cool, the heat just punches straight through to rag top I also don't have enough hair for the "wind in the hair" experience, so there is that....LOL
    • joshuaho96
      Cas issue

      By joshuaho96 · Posted

      Could be falling edge/rising edge is set wrong. Are you getting sync errors?
    • joshuaho96
      Jacks that fit under GTR lips that can reach the subframe?

      By joshuaho96 · Posted

      On BMWs what I do because I'm more confident that I can't instantly crush the pinch welds and do thousands of USD in chassis damage is use a set of rubber jacking pads designed to protect the chassis/plastic adapter and raise a corner of the car, place the aforementioned 2x12 inch wooden planks under a tire, drop the car, then this normally gives me enough clearance to get to the front central jack point. If you don't need it to be a ramp it only needs to be 1-1.5 feet long. On my R33 I do not trust the pinch welds to tolerate any of this so I drive up on the ramps. Before then when I had to get a new floor jack that no longer cleared the front lip I removed it to get enough clearance to put the jack under it. Once you're on the ramps once you simply never let the car down to the ground. It lives on the ramps or on jack stands.
    • GTSBoy
      Mistakes were made, my R34 Story

      By GTSBoy · Posted

      Nah. You need 2x taps for anything that you cannot pass the tap all the way through. And even then, there's a point in response to the above which I will come back to. The 2x taps are 1x tapered for starting, and 1x plug tap for working to the bottom of blind holes. That block's port is effectively a blind hole from the perspective of the tap. The tapered tap/tapered thread response. You don't ever leave a female hole tapered. They are supposed to be parallel, hence the wide section of a tapered tap being parallel, the existince of plug taps, etc. The male is tapered so that it will eventually get too fat for the female thread, and yes, there is some risk if the tapped length of the female hole doesn't offer enough threads, that it will not lock up very nicely. But you can always buzz off the extra length on the male thread, and the tape is very good at adding bulk to the joint.
    • Duncan
      Mistakes were made, my R34 Story

      By Duncan · Posted

      Nice....looking forward to that update
×
×
  • Create New...