still getting top end cut out (death)
Turbo Mini Forums

im still getting this top end 3rd and 4th cut out, it does it worst when i use 3rd to high revs then into 4th and it dies. seems to drop to idle and wont pick up?

from what i can remember it started doing it when i fitted my new head around 4 months back.

could it be carb icing? as ive never experienced it i dont know what happens.

any advice would be great cheers

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Explain better.

Is it like a rev limiter, a total engine cut ? Exactly what rpm ? Boost level ? at all times and loads ?
Always in 3rd/4th or just sometimes ?

ie hold at say 6000rpm in 3rd or 4th and light throttle then plant it and what happens ?

But initial thought would be lack of fuel supply to the float bowl.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I agree with Steve,

check the fuel reg for crap, and if you can see the ruel return in the tank have a look when its doing this idle thing, see if its intermittant.

Just been specking to ron and we think it culd be carb icing cause by it being a tad lean,

Going to do some fettling

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

I can't see it being carb icing. Doesn't sound like the symptoms. with carb icing I found it ran ok at speed, but wouldn't tickover and was apain part throttle.

Id does sound like you are running out of fuel though.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

Which air filter you have?

Pedro Silva

http://miniciados.blogspot.pt/

I don't think its icing mate. If you say it's going up to the 13's on the AFR it's too lean. Either check you reg or give the needle a tweak.

Similar issue to what I had after my RR session.

Ron

fueling issue, if you havent an AEM lambda get one

Have got 1 benross, I think im going to change the jet to a richer 1 and profile a needle to suit

My current needle is like a pin

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Have got 1 benross, I think im going to change the jet to a richer 1 and profile a needle to suit

My current needle is like a pin

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Valve guides?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Nic why wuld it be valve guides,

Its very hard to describe

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

You can't change the jet, well not for a bigger one. it's a standard part, the fuelling is set by needle profile.

Valve guides can nip up giving a misfire, Nic spent a long time finding it on his car.

You need to check the float bowl for any restriction in the feed, like the little filter. then you need to look at what your pump is pumping.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

are you using the T piece mod / trick?
definitely sounds like a lack of fuel, with carb icing the engine still runs as far as ive know/ and tends to happen at part throttle cruise

is it a weak fuel pump? and your running more boost than it can pump (thus emptying the bowl on longer gears)

Edited by Brett on 26th Nov, 2011.

Yes i moved to the darkside

Instagram @jdm_brett

ive checked the float bowl, and pump.

if im driving foot down in 3rd, it will get to around 6000 ish and then die. as if its cut out.

i dont get a lean out when this happens (altho it will be around 3.2 afr)

and i have to wait for around 5-10 seconds before it will drive again. if i try it will make a whisle come chatter noise?

does that make sence?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

Still sounds like lack of fuel supply.

And the slow recover time again would suggest to a lack of fuel supply.

What does fuel pressure do during this ?

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

what boost are you running?

does it do it if you turn it down a bit?

My build thread..

http://www.turbominis.co.uk/forums/index.php?p=vt&tid=542985

Sounds like fuel supply to me too. More than likely down to a blocked filter in the tank or a worn fuel pump.

Have you tried accelerating part throttle up to 6k and see if it does it then?

Edited by matty on 26th Nov, 2011.

https://www.facebook.com/pages/Fusion-Fabri..._homepage_panel

www.fusionfabs.co.uk



1/4mile in 13.2sec @ 111 terminal on 15psi

this could be Boost Bog, ie too rich, i have suffer with these symptoms once!

is it black smoking befor this happens ?

if the above try leaning out the carb with the screw, if not change the needle for a standard BDD and go from there using the Lambda.

the valve guides if they are manganise bronze could cause these symptoms if they havent been reamed out when they fitted............. the guides nip when thay are hot then cools and the guides go back to normal on the exhaust valves,

you mention no missfiring so its not the guides .... go for boost bog if there is black smoke,

keep us posted

Edited by BENROSS on 26th Nov, 2011.

theres never any smoke, and its one of your heads benross.

from what everyone's saying i think it must be fuel, how do i go about richening top end even tho my needle is like a pin?

13.95 1/4 mile on a 2.95 fd. Carnt be that hard to beat!

However the noise when the valve guides nip up could be confused with a misfire to the inexperience ear, I'd put it down as a chatter noise myself.

As you said you don't get a lean out so that rules out fuel starvation.

The fact it started when you fitted a new head is a big clue.

I don't know if they have changed the metal of valves or the guides but I've heard increasing tales of this over the past few years

I read the advice on here and rebuilt my carb, changed fuel lines, changed fuel filters, changed the pump before a 9/32" reamer fixed it.
Even if previously reamed they may be a little tight when hot.

A rich missfire will show up as a lean AFR on any wideband controller.

And a rich missfire on all cylinders means the engine is not running. The few seconds it takes the engine to recover is the engine drying out the spark plugs.

I suffered a similar thing when I ran the nitrous, and it only showed in fourth at the top end. leaned it off a little and it sorted the problem, but it was still 10.5:1 rich.

One other thing, you are using resistor plugs with megajolt?

Edited by Sprocket on 26th Nov, 2011.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will