Jump to content
SAU Community

Recommended Posts

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

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.,

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

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.......

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.

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

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

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

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

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 :)

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


  • Similar Content

  • Latest Posts

    • GTSBoy on your suggestion on another thread I had a look at those injectors and ended up getting them because of the quality.  Got the expensive ones.  
    • Hey guys been looking everywhere to try and find the correct gtr hood latch support part number but only found the first half and when I search with that number it sends me to an r34. The first part I found was 62515. If anyone could help me with the rest then I’d really appreciate it. Or if there’s some alternative hood latch support that would work even better cause I can’t find any for sale. (Searched on upgarage, partsouq,buyee,rhdjapan) 
    • If you've only done the upper control arms on the rear, AND you have changed their length (by more than about 1mm) to set the camber you want, then you will definitely need/want to install traction arms also. Adjusting the camber arms on their own WILL introduce bump steer and make the car unpleasant to drive. Most owners have no idea that their car could behave infinitely better than what they put up with. I'm not entirely sure what the Stageas need, but I am thinking that unless you have massive front spring rates and pretty soft rear springs, you have waaaay too much rear bar. Oversteer city, in my estimation. Combined with possible excessive bump steer from maladjusted arms, that could be a recipe for nastiness. ATR43SS2 is not a highflow. It is an outright replacement turbo. It's a little bit bigger than the largest highflow profile that Tao does. Probably a solid 300rwkW turbo where the bigger highflows will be about 30-40rwkW less. Nevertheless, we're only talking about ~300 rwkW, which is well within the abilities of the stock ECu to run with a Nistune on board. I would do so without hesitation - and I will be doing so when I get my finger out and actually get the injectors and AFM installed. But, if you would prefer to drop a whole lot more money on the ECU side, then I suspect you're looking at Haltech. The Haltech fanbois here will all spout on about all the available engine protection you can have, that you can't have with the Nistune option. And they're right. But it doesn't really come for free either. You will spend more money on extra sensors and the like, plus the work to install them. If the engine was built and therefore represented a big investment to protect, then I'd say definitely do it. If you view the current (and forever into the future) shortage of replacement engines as something to prompt similar protection, then also, do it. If you see a destroyed RB25 as an opportunity to put in a Mercedes or other V12 (like I kinda do)... then your perception of the risk/reward might differ. These are good injectors. You can also get a "better" set of the same with more flow matching, for more $$. 1000cc is where you will want to be. You will need an R35 AFM and adapter tube if you want to stay with Nistuned stock ECU. Otherwise, if going Haltech, you can ignore. As for intercooler. Just about anything will do. You're only talking about ~300rwkW. Just put a big core in there. Be aware that return flows do add significant pressure drop and will cost power and will make the turbo work harder to achieve the same goals. If you can manage a proper crossflow, do it. I'm keeping my very good return flow because I'm only expecting to be in the ~250rwkW range, and will live with whatever outcome I get.
    • I have a heap that i have collected if you want some authentic ones still. Pm me if your interested!
×
×
  • Create New...