924Board.org

[chris79]

Yesterday I was to track day in Franciacorta track, my car recently run well and I have no problem.
But in track when I accelerate quickly the engine misfire a lot and performance are very poor, in road I have not this problem.
It can be the setting of advance ? Now this is set with lamp, it may be that corrector of advance increase too much advance when I accelerate quickly?
_________________
Porsche 924 2.0 na 125hp (1979) euro
------------------------------------------------------
Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro

[chris79]

I found 2 possible causes, weather hot might have changed warm control pressure and then fuel mixture (there was 3.2 bar before track day, today is 3.7 bar) or jumps due to driving on track moved screw of co setting (there was little smoke from the exhaust).

It's possible?
_________________
Porsche 924 2.0 na 125hp (1979) euro
------------------------------------------------------
Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro

[Fasteddie313]

If the WUR caught some gunk and clogged a bit I could see control pressure rising..

Brand new WUR right? Maybe you just broke it in and you need to readjust CO to compensate, you seem to still be within spec...

Higher control pressure would push you lean, I hope you didn't run it too hard like that..
_________________
80 Turbo - Slightly Modified

[Cedric]

Misfire sounds like something else, overheated ignition coil?
_________________
1980 924 Turbo
www.instagram.com/garagecedric/

[chris79]

I tried to regulate Advance and co with small changes but there are no noticeables improvements.
Primary fuel pump is noisy, I have to test even if fuel pump in tank work correctly.
Often poor performance is due to secondary fuel pump, even Engine sound is changed.
There is even noisy from distributor, I have to made some works.
_________________
Porsche 924 2.0 na 125hp (1979) euro
------------------------------------------------------
Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro

[chris79]

Even fuel pump relé very warm.
If fuel delivery for 30s is 750mm and control and system pressure are ok test of pumps is completed?
Or it's possible that at maximum speed the secondary fuel pump don't make necessary fuel to primary pump?
_________________
Porsche 924 2.0 na 125hp (1979) euro
------------------------------------------------------
Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro

[chris79]

this is video of misfires and performances was very bad, maximux sped about 150 - 160 km/h:

https://www.youtube.com/watch?v=ldPCSHoxxlU&feature=youtu.be

fuel pump makes a strange noise, I think no enough fuel comes to the injectors.

Before engine was perfect, then shortly before go on track engine changed sound.
_________________
Porsche 924 2.0 na 125hp (1979) euro
------------------------------------------------------
Alfa Romeo Spider "Duetto" 1.6 104hp (1986) euro