Jump to content
SAU Community

Rb25det Boost Problem

Quinny

By Quinny,
in Engines & Forced Induction

 Share

Recommended Posts

Quinny Rising Star

Quinny

Posted
  • Author
Posted

I had yet another thought with my car. The car seems to be flat-spotting at around 2500-3500 rpm. The more I think about it, the more it seems to be a flat spot rather than a clutch problem. Usually with clutch slip, the car will rev quickly but not go anywhere. Mine sort of revs, then hits 2500-3000, just as boost is coming on, and sort of dies in power, when I bury the foot, it is almost like a really sloppy auto downchange, the revs creep over 4000rpm, then it revs ok from there.

Would it be worthwhile resetting the ECU? I have read that a few people have fixed flat spots like that.

The car is getting serviced next week with new plugs, and the clutch will also be checked, but I am starting to wonder if it actually is the clutch.

I have also noticed that the car seems to run a bit rich - you can smell it (not too strong, but you can still smell it) - would this contribute to my problem?

Any other ideas - or is the clutch still #1 suspect?

justin911 Grand Master

justin911

Posted
Posted

drive the car.... change to forth gear and make the car come on boost quickly.... if your revs are going up but the car isnt realy moving then its the clutch... from what you've said it sounds like the clutch... ( i just replaced mine a week ago.. i had the same problems)

if it was the spark plugs etc.. the car wouldnt be revving still

Quinny Rising Star

Quinny

Posted
  • Author
Posted

Yeah, 4th gear does the same thing, but it is most noticable in 3rd. In my previous experiences with clutch slip, the engine usually revs, but you don't go anywhere (or not very quickly), in this case the car sort of hits a dead patch where it just does not really want to rev, but once it gets over 4000 it is ok..... weird.

I might try resetting the ECU - no harm in that. If it is the clutch, then that will be replaced soon too...

MKDR33 Mentor

MKDR33

Posted
Posted (edited)

I used to get a similar problem, when i boosted my car to 12psi or more, got a flat spot between 4500rpm and 5500rpm.. Updated coil pack issue ---> http://www.skylinesaustralia.com/forums/in...howtopic=119403

Edited by MKDR33
Quinny Rising Star

Quinny

Posted
  • Author
Posted

I just took the car for a drive, it is definitely the clutch. I did a few tests - took off in 3rd gear, clutch slipped until boost came on and the car took off. I also tried mid-gear acceleration and the revs slipped right to 7000 before dropping back to 4000 or so to pickup again.

I am convinced now it is definitely the clutch, and it needs to be replaced soon.

Quinny Rising Star

Quinny

Posted
  • Author
Posted
easy way to tell if it's the clutch -

1. Stop

2. Put it in 4th Gear

3. Try and take off.

4. If the car stalls, then not the clutch

5. If the car rev's up and carries on, clutch is shagged.

I tried taking off easy in 3rd, and the clutch slipped until it hit boost then the car took off, so I think the clutch is stuffed. Also the fact that in any gear, if I bury the foot, the revs slip to 7000rpm before dropping back to about 4k to accelerate again.

Quinny Rising Star

Quinny

Posted
  • Author
Posted
with about $1k spare, you'll be able to get a nice 3100 poundJim Berry Special. It will never slip again :sweat:

(until you put about 350rwkw through it)

I can get a brass button clutch with a sprung centre for $430, so I think that might be the go. I have no intentions of 350rwkw at the moment.

I drove the car today...... clutch is screwed. Big Time., I think last night when I took the car for a drive to test the clutch out, I think I gave it a bit too much of a hiding, because the clutch slips at any revs now, even like 1000rpm.

Quinny Rising Star

Quinny

Posted
  • Author
Posted
go for it.

Don't be worried, a clutch is a consumable like tyres or a fuel filter. They wear out.

Just get her changed and you'll be back in business. Get a nice "on off" style clutch. They are fun.

Yeah, I am not too worried if it is only the clutch, I am glad it wasn't something worse. I will be getting the brass button clutch, but the sprung centre will help the on/off action a little, so it isn't quite as violent so it is better in traffic. The place I am getting it from says that it is the toughest single plate clutch they make for the GTS-T, and will take over 350rwhp with no troubles. Not bad for a $500 clutch.

Quinny Rising Star

Quinny

Posted
  • Author
Posted
Definately the clutch, i'd suggest you stop "testing it" before your flywheel is beyond machining.

Yeah, I have learned that lesson. The car won't go anywhere without slipping really badly. The only trip it will make now is down to the mechanic to get a new clutch. If the flywheel gets screwed, that is a pretty good excuse to get a nice lightened one. :)

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...