Jump to content
SAU Community

Recommended Posts

Hi peoples

Now this is really f&*$^*n pissing me off. I’ve got an rb20det in a 180sx. I can drive the car fine makes boost well and then bam at 6000rpm I loose all boost as in it’s running 0 psi. At first I thought it was my wastegate cause I bought a cheap imitation off the net, but then I changed that to a genuine Tial wastegate and still the same. For the love of god guys I got spanked by an xr6 he handed me my own arse and all I could do was hang my head in shame!!!! What could possibly causing this huge lose in power. Well the cars got all the normal GFB like fuel pump, injectors, AVCR, ECU, fmin, zorst, but where it might be getting let down is the turbo, ive got one of those cheap ebay copy xs-power turbos, I got it balanced when I baught It and all, could that be the problem?? Please help, please. I don’t care how stupid it may sound tell me what you think it could be.

Waiting in anticipation

Anthony

Link to comment
https://www.sau.com.au/forums/topic/94219-no-pwer-past-6000rpm-rb20det/
Share on other sites

when does your boost cut out normally? before it started at 6000

It would go right up to redline no problem. the bastard used to fishtale into second and step out going into third now nothing. The rev limit is set up at 7800rpm and it would hold boost the whole time thats on standard 8psi setting a on 14psi and setting b on 18psi.

now goes up to 8psi then at around 6000rpm (probably colser to 5500rpm) just falls flat on it's face

Cheers

anthony

What were you doing when all this happened? Even crap turbos wouldn't just suddenly dump all boost.

Dunno one day power next no power.

i thought it's cause it took it drifting but even after takin it driftin it was fine then a couple of weeks later it all fell to shit.

Cheers

anthony

your going to need to go into more detail if you want us to debug it over the forums. failing that maybe take it a to a real machanic and take them for a drive in it or get them drive, sometimes its much easier.

so you drive along boost is normal rising until it hits target boost and then at 6000rpm it goes from say 12psi to 0psi and you have no boost at all? is that correct? does this happen every time or once every now and then? does it happen over and over on the same drive / test run or is it just when it feels like. when it does work "ok" does it stay at 12psi and keep that until redline ok?

do you have any pops, noises, bangs, kabooms, smoke, whines?

are you seeing any oil around the intake components, bov seal, cooler piping areas, throttlebody join up pipe?

what boost controller and wastegate pressure spring are you using

when did it last work "ok"? whats changed since then?

nevermind just read avcr, what does it display when the problem happens?

when you MONITOR and choose BOOST and do graph mode does it actually show the manifold pressure taper off to 0psi past 6000rpm or are you just exaggreating it?

have u tried bypassing the avcr and running direct of the actuator (int gate) or the external gate spring only. does the same problem when you do this? if so that would rule out the avcr being stupid

nevermind just read avcr, what does it display when the problem happens?

when you MONITOR and choose BOOST and do graph mode does it actually show the manifold pressure taper off to 0psi past 6000rpm or are you just exaggreating it?

have u tried bypassing the avcr and running direct of the actuator (int gate) or the external gate spring only. does the same problem when you do this? if so that would rule out the avcr being stupid

I took it to my tuner he took it for a drive and said it seems to be the waste gate cause it looks like it's just stayin open past 6000rpm (really bout 5500rpm) and that's why it' not makin any boost. so i then baught a new tial wastegate and put it on today and it's the same problem.

And i kid you not it says o psi on my boost gauge and the car seems to be goin backwards.

No strange noises nothin just 0 boost, it has me baffled. i just ran it on standard boost which is .8 bar and it goes up to 9psi and holds that to bout 6000rpm and then back down to 0.

i really really really wanna get this fixed it's just pissin me off now!!!!!!!!!!!

Thanks for the replys guys

Anthony

odd problem to have. i got no idea. even if the spring was shagged you would still make some boost one would assume? have you checked cooler piping areas for leaks and/or signs of it coming loose? sounds like one of those could be leaking under pressure. is it always poast 6000rpm?

odd problem to have. i got no idea.  even if the spring was shagged you would still make some boost one would assume? have you checked cooler piping areas for leaks and/or signs of it coming loose? sounds like one of those could be leaking under pressure. is it always poast 6000rpm?

Yea always past 6000rpm like i said like a light switch it just goes down to 0 PSI

it doesn't seem to be leaking boost prior to that throughout the rev range.

Cheers

anthony

Can you hear the turbo spin up? And does it sound like it stops when the boost drops to nothing or is it still spining?

Dyno is your friend, get it on and have a listen/look to see whats happening in a controlled environment. If you have a leak it'll be easy to find if it's big enough to bleed off all boost. If your turbo is suddenly seizing you will hear it.

Edited by BHDave
Can you hear the turbo spin up? And does it sound like it stops when the boost drops to nothing or is it still spining?

Dyno is your friend, get it on and have a listen/look to see whats happening in a controlled environment. If you have a leak it'll be easy to find if it's big enough to bleed off all boost. If your turbo is suddenly seizing you will hear it.

It does'nt sound like the turbos seizing, and i cant really see any leaks

Cheers

anthony

Im going to have a stab..

Sounds like your wastegate is opening when the max boost is reached and then staying open?

Have you re tuned the avcr since you changed wastegates? Maybe do that. Or maybe they have plumbed it up wrong?

Im going to have a stab..

Sounds like your wastegate is opening when the max boost is reached and then staying open?

Have you re tuned the avcr since you changed wastegates? Maybe do that. Or maybe they have plumbed it up wrong?

Thats an idea but it was workin fine before with the exact same setup and now it's not.

do you think i should still check it??

Cheers

anthony

Well guys

I took the car to hitman and he didn't even put it on the dyno like i wanted him to he just took it for a drive cheked the BOV and he said check the cat it could be blocked, but how the f*^&k could the cat being blocked make 0 psi boost????

The car is not running on 0 psi like i thought ( by the way the boost cutting out is happening at 5200rpm and in higher gears it's less) it's actually running vacume

So much for the Dyno

Cheers

anthony

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

    • It would be different if the sealant hadn't started to peel up with gaps in the glue about ~6cm and bigger in some areas. I would much prefer not having to do the work take them off the car . However, the filler the owner put in the roof rack mount cavities has shrunk and begun to crack on the rail delete panels. I cant trust that to hold off moisture ingress especially where I live. Not only that but I have faded paint on as well as on either side of these panels, so they would need to come off to give the roofline a proper respray. My goal is to get in there and put a healthy amount of epoxy instead of panel filler/bog and potentially skin with carbon fiber. I have 2 spare rolls from an old motorcycle fairing project from a few years back and I think it'd be a nice touch on a black stag.  I've seen some threads where people replace their roof rack delete with a welded in sheet metal part. But has anyone re-worked the roof rails themselves? It seems like there is a lot of volume there to add in some threads and maybe a keyway for a quick(er) release roof rack system. Not afraid to mill something out if I have to. It would be cool to have a cross bar only setup. That way I can keep the sleek roofline that would accept a couple bolts to gain back that extra utility  3D print some snazzy covers to hide the threaded section to be thorough and keep things covered when not using the rack. 
    • Probably not. A workshop grade scantool is my go to for proper Consult interrogation. Any workshop grade tool should do it. Just go to a workshop.
    • In my head it does make sense to be a fuel problem since that is what I touched when cleaning the system. When I was testing with the fuel pressure gauge, the pressure was constantly 2.5 bar with the FPR vacuum removed. When stalling, the pressure was going up to 3.0 bar (which is how it should be on ignition).
    • ECUtalk pages don't mention they support the ABS computer (consult port has more than one CAN), so you might just need a different scan tool. But, I would expect ABS is a different light to the brake warning/handbrake light, do you see an ABS light come on for a few seconds when you turn the key from ACC to IGN? But since you said: I'd have a look at the ABS sensors in the rear hubs to make sure they are not damaged, disconnected etc.
    • OK, if it idles at 1000+ with the AAC, its not an idle airflow problem. The cold start valve just gives extra air when the engine is cold, but you have enough air without it to idle at 1000. I think you are back to a fuel problem, sorry. Can you see the fuel pressure staying constant or does it drop as the revs drop to a stall?  
×
×
  • Create New...