Boost/Acceleration Issues

Good Evening guru's

Got a quick question for you all..

Have a R33 25T, and seems whenever you accelerate up, even just moderatly (anywhere from 2nd to 5th gear), the boost will jump to almost max and the revs climb to 4 or 5 and the engine makes alot of noise, but isn't going anywhere.

I'm going to get it looked at, but was just curious what it is, or could be, might save me the heart failure at the mechanics.

Haven't moded my car, but have changed the oil and filter since this has started...

Any feedback is most welcome, have a good night.

From my rudimentary knowledge, it's either your clutch is in a very bad shape or your gearbox has taken leave.

Well, if it is a clutch, least that isn't the zillions the turbo would cost me.... then again, gearbox, sounds ominous too...

Thanks for your input. :)

I had that sort of thing happen to me once, the mechanic that WAS looking after my r31 forgot to do that little clamp up that keeps the hose attached to the manifold over the top of the engine. Every time I hit boost it would rev out like you say because all the boost pressure was escaping.

Its because you left the handbrake on.:D

Just kidding.
Doc

I had that happen to me. It was clutch..... next time it happens stop the car and see if you can detect a strange smell from you car...... thats the clutch burning! :)

Cheers
Zapf

I have had this problem a lot, it has always been tuning issues. I can make it happen any time I like. Retard the timing too far... You'll find that the car will go OK on a certain amount of boost but if the boost rises too high, it just bottoms out.

A disconnected vacuum hose could certainly do this aswell.

Could also be plugs? I find that worn plugs have a hard time sparking correctly if the boost goes too high for them, also creating flat spots on full boost.

Have you done anything to the car lately?:confused:

Usually when mine revs to the redline but doesn't go anywhere, it's because the rear tyres are sh*tting themselves :D :devil:

Er, a decent clutch cost about the same as rebuilding a turbo :)

I just put a new clutch in my car last week. Cost $290 + GST from ADL for a standard clutch or I think $540 for a HD clutch

To check if the clutch is dead or just about, put it in 5th gear while parked and take your foot of the clutch, if the engine keeps running it is your clutch. you may need to put just a few revs on.

:smoka:

That is damn hard on the clutch.... any clutch will slip if you try and take off in 5th..

It is obvious when the clutch is worn, the pedal will be along way of the ground.. and even after adjusting it... it will still have alot of travel.

Most of the time by putting your foot down in 4th and it slips is a good way to know.

Ben

Falic, is that $290 fitted or just the clutch?

I found another problem that was causing my bottoming out at high boost. there is a vaccuum line coming off the plenum to an electronic sensor for the ECU. the previous owner had a turbo timer installed (with digital boost guage) and had put a T piece in this line which was oversized and split the hose, leaking boost pressure and therefore sending an incorrect reading to the ECU.. causing this bottoming out at high boost (I guess the mixture would have been leaning out or maybe timing was off as a result of this).

Try checking hoses like this one for your problem, you might have some luck.

Just the clutch, I fitted it myself.

Taking off in 5th stalls my car, but it would just sit there and idle if it is worn out, mine did it in 1st.

Too much fun.

Hey SLow GTS-T

I noticed your comment on rebuilding a turbo, so I thought I would mention that I replaced my turbo a couple of months ago, for $250.00
and fitted it myself.
I also had to do exhaust studs, 5 of them to be exact, (major mission especially the back one) plus gaskets.

Also a coil which I can get for $60.00 + each, guaranteed, unlike Advanced imports.

Hey all ... I was just wondering around the forums and found this thread ... well i have the same problem as he does .... a flat spot at high boost and boost rising to 9 very fast ... up to 5 does not rise but once it goes beyond 5 ... i cant controll it its either 9 ... or 5 ... cannot get the car to run at 7 or 8 psi ... I had some problems with starting up some times so I decided to get some new plugs ... fitting them next week ... as you said it might be worn out plugs ... I hope this fixes both starting prob and the flat spot ... after fitting new plugs planning to go to advanced imports or any where else .. ( a tuneshop) and get it looked at by the pros:bloated: and getting all the maintenace stuff right such as injectors cleaned ... fuel filter ... checks for nearly everything .. i hope ... I havent dynoed my car yet ... but I know wat the figure will be .. PATHETIC lol

Here is another thing to consdier, it may be your afm causing the flat spot.
I have had mine replaced, but I have found out what goes wrong with them most of the time, they get a carbon, or dirt build up on the wire inside them.
Very carefully clean this wire, with a soft toothbrush or similar, be very careful with it thought, as it is fragile, and if you do break the wire you will have to replace the AFM, I am not sure if you can just replace the wire in them, as I have not done it myself, but I have cleaned it since then.

Remeber to be very careful.