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

    • Ok i will get those 310mm. I found one but on a different site. This is the description on those...is it ok? Technical parameters: - Axle: front. - Disc type: ventilated. - Number of holes: 5. - Disc diameter: 310mm. - Total height with center: 54mm. - Thickness (new/min.): 30/28mm. - Designed for brake calipers manufacturer: Sumitomo.
    • You Gregged a whole racetrack!?
    • Look for broken wire or bad connector at the motor. Might not be it, but is worth starting there, as it is easy.
    • Hi everyone, I’m having an issue with my R32 GT-R. Sometimes, when the car goes over a bump or experiences some vibration, the 4WD warning light comes on the dashboard. When I check the code from the control unit in the trunk, it shows Code 19 – ETS Motor. However, everything seems to be working fine — if I turn off the engine and restart the car, the light goes away and everything functions normally. Has anyone experienced this before? Where should I start troubleshooting this issue? Thanks in advance!
    • I'm back from the dyno - again! I went looking for someone who knew LS's and had a roller dyno, to see how it shaped up compared to everything else and confirm the powerband really is peaking where Mr Mamo says it should. TLDR: The dyno result I got this time definitely had the shape of how it feels on the road and finally 'makes sense'. Also we had a bit more time to play with timing on the dyno, it turns out the common practice in LS is to lower the timing around peak torque and restore it to max after. So given a car was on the dyno and mostly dialled in already, it was time for tweaking. Luis at APS is definitely knowledgable when it came to this and had overlays ready to go and was happy to share. If you map out your cylinder airmass you start seeing graphs that look a LOT like the engine's torque curve. The good thing also is if you map out your timing curve when you're avoiding knock... this curve very much looks like the inverse of the airmass curve. The result? Well it's another 10.7kw/14hp kw from where I drove it in at. Pretty much everywhere, too. As to how much this car actually makes in Hub Dyno numbers, American Dyno numbers, or Mainline dyno numbers, I say I don't know and it's gone up ~25kw since I started tinkering lol. It IS interesting how the shorter ratio gears I have aren't scaled right on this dyno - 6840RPM is 199KMH, not 175KMH. I have also seen other printouts here with cars with less mods at much higher "kmh" for their RPM due Commodores having 3.45's or longer (!) rear diff ratios maxing out 4th gear which is the 1:1 gear on the T56. Does this matter? No, not really. The real answer is go to the strip and see what it traps, but: I guess I should have gone last Sunday...
×
×
  • Create New...