Hissing on boost, under load no power
Turbo Mini Forums

As stated above i seem to be getting a rather annoying hissing sound on boost and a lack of power whilst under load,
Rebuilt the carburettor from start to finish today as i thought it was the throttle spindle seals, took it out and ran like an absoloute dream, given about half an hour the hissing came back and got worse and worse and back to how it was before.
Getting really annoyed with this as ive racked my brain for months to work this out and still no joy.
It definately feels like starvation of some kind. Also the boost gauge reads fine.

Any pointers will be much appreciated!!

Low boosting for now.

Massive Boost leak?

Are all your clips tight?

In the 13's at last!.. Just

dump valve fucked.

original dump valve not blocked.

What Joe says.

or dump valve full of petrol.

dump valve or split in boost pipe thats not immediately noticable ,take the pipes off and check, and try a different dump valve

give em hell

Check all hose joints, and as the gents. State,

You will find it keep looking,

Okay guys, if it turns out to be the original dump valve or something so silly ill be so pissed,
Thing is tho its intermittent? Surely it would be every time as opposed to under load?

Low boosting for now.

not necceseraly a fecked one will give the symptms you have

give em hell

my popper valve on the plenum was glued up by the previous owner. This broke for me and gave symptoms as you describe. was intermittent based on the load i was giving it. Boost gauge read full boost but it was clearly leaking. I glued it in place with some liquid metal. worked a treat.

1275 N/A Sprite, 998 T2 Turbo Mayfair
1275 EFi Turbo

Sounds like this could be my best bet then, ill whip it out after work and look at sorting it out! :)

Low boosting for now.

Haha lol.

Low boosting for now.

I had no heat sheild on mine and the holes on the plenum went through so had big boost leak

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

Just checked my old plenum and they appear to be blind holes,
Think the problem lies in the plenum trumpet i have, ill upload a piccy, its cut right back and im only really managing to clamp on the taperd part hence why it gets worse and worse as i think its sliding off the trumpet, thus leaking more and more, if i wiggle it like mad it eventually pops off no matter how tight i do up the jubilee or mikalor.

Low boosting for now.

Low boosting for now.

Mines the same and its fine at 25psi

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

Thing is tho when i re clamp it it runs nice for a bit then slowly comes back, repeat the process the same happens.

Low boosting for now.

Ideally, you need someone to run a bead of weld around to make a retaining lip, but if you put three self tappers in around the edge and then clamp the hose behind their heads I would be very surprised if it came off again.

Having doubts to weather this is actually the problem now,
It seems to be worse on part throttle boost, almost like someones stamping the brakes.
But if i back off and press the loud pedal all the way down its fine.

Low boosting for now.

get some soapy water on your pipe if you don't want to take it apart but to glue up the plenum is an easy 30 min job. You may as well just try it.

Edited by dan187 on 4th Dec, 2012.

1275 N/A Sprite, 998 T2 Turbo Mayfair
1275 EFi Turbo

Block off the compressor housing on the turbo so it won't leak air. Adapt a fitting so the airline can be connected to theengine. Full with air to the desired pressure and have a look to see where your leaks are. Works a treat. You will be surprised to see what leaks!

Oh my god, why did i not even think that! *slaps head*
Thanks pal.

Low boosting for now.

Did a pressure test, found a hose with a split, however tried sleeving the split, no joy still 'pssshhhh' and no power, just went to the extent of going back non intercooled as the standard setup would be, and hey presto, no joy, i really cannot work this out its been ages now and am really getting fed up with it.

Low boosting for now.