scoootie5

I have a problem with boost spiking with a Dawes device.

I think that is what it is anyway, It does not matter how low I turn down the Dawes MBC the boost spikes over 1bar after 5000rpm, and Det appears on my Knocklink then I either get the fuel cut or a surging effect.
I have turned up and turned off the FCD and it has made no difference. I have read some old posts and I will be opening up the bleed hole on the Dawes from 0.5mm to 1.0mm.

Do you think this will cure the problem or have any other ideas?

Thanks
Scott

john banks

Clean the Dawes, check the ball surface is smooth and that it is not sticking. Check the play on the wastegate arm. Check for vac leaks.

scoootie5

Anyone????

I have drilled out the bleed hole to 1.0mm on the Dawes and it has helped, but still getting the dreaded lights but not as bad now.

I am getting fed up this problem now as I have been try to sort it out for 3 weeks.
So I am going to remove the D/P splitter and see if this sorts out the problem. I have ended up undoing everything I have done and it is very annoying.

Thanks
Scott

john banks

I am using the same downpipe with a splitter in the exhaust housing and even with a 20G it doesn't boost creep or spike.

scoootie5

Ok, I will hold on that then, thanks

20G ???

God knows what the problem is. It is probably something stupid I haven't noticed or maybe my Knocklink is too sensitive.
I am just worried that I am going to pop a piston again.....

Thanks
Scott

scoootie5

Just had a thought could a very noisey tappet cause the knocklink to light up????

The noisey tappet is on the cylinder below the knocksensor.

Justa thought

Thanks
Scott

scoootie5

Happy Days!!!

I have set my boost at 1bar now and the knock has gone.

So whatever I did last night fiddling or my new tank of fuel tonight has sorted it. I have aslo removed my Dawes FCD maybe it was leaking when I did not want it too!!

Will try it again tomorrow and mark the Dawes and slowly increase to my old setting and see what happens.
If it still okay to fuel cut then I will put my FCD on again and see..

Thanks
Scott

scoootie5

Done, done, done and done

I already took apart the Dawes and cleaned it with Carb cleaner and pushed a pin through the bleed hole. The Wastegate arm has no play as I tightened it up 6 months ago but I did also check the wastegate was opening and not fouling my D/P splitter.........

Have checked all the vacuum pipes for any abrasions or leaks and all seem ok. Can't hear any hissing on idle either.

I am thinking that maybe my D/P splitter is restricting my wastegate flow and I am getting Boost Creep (read other post 2 mins ago). I do have a wierd D/P from Revolution and it is not a true open neck but in between. Not fully open . . .
But I did port the D/P as much as poss. (see scribble on pic).



Am I barking up the right tree???

Thanks
Scott


[Edited by scoootie5 - 4/8/2003 11:35:40 PM]