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Coughing around corners!
Bass1st - 14/6/10 at 06:51 PM

I went out for a quick blast on Sunday and attempted some high speed cornering around some roundabouts. Car handled really well, however I got a really bad cough/splutter from the engine. Wondering what is happening? Not noticed this before! Running DHLA 45's on a 16v 4age. Car was recently tuned up at Northampton Motorsports.

turbodisplay - 14/6/10 at 06:57 PM

Do you have a swirl pot to enable fuel flow is maintained during hard cornering?

Darren

cliftyhanger - 14/6/10 at 07:18 PM

Bet it is over-fuelling. Had it on dellorto 40's on autosolos. Car kept dying/spluttering and black smoke out the back, nasty.
There is a work-around I saw (meant for off-road vehicloes!) which involved a drain/overflow and electric pump to remove excess fuel. Think it was the powertune book.
They overfill the chamber as the fuel surges, float dropas and lets more in, tehn as the surge returns level it is overfull.....bit of a bu*****er and all that, one reason to go EFI!

snapper - 14/6/10 at 07:29 PM

If the fuel tank is not baffled the a swirl pot will be needed.
Fill tank to brim, go for another quick spin, if problem is not there it's the tank

RichardK - 14/6/10 at 07:34 PM

Not as bad as mine farting over speed humps!

Regards

Rich

Bass1st - 14/6/10 at 07:44 PM

I don't have a swirl pot and not sure if the tank is baffled of not - how do I tell? Tank was 95% full when I went for a run. I am running a facet pump via a filter into the carbs.

stevebubs - 14/6/10 at 07:55 PM

So the consensus is it's either going to be over or under-fuelling.

If under, then there's not enough flow to the carbs..swirl pot or baffle in tank...

If over, you could try dropping the fuel pressure down a bit....

No easy way to tell unless you've got a WB lambda you can borrow?....

stevebubs - 14/6/10 at 07:56 PM

quote:
Originally posted by Bass1st
I don't have a swirl pot and not sure if the tank is baffled of not - how do I tell? Tank was 95% full when I went for a run. I am running a facet pump via a filter into the carbs.


No Pressure Regulator??

Bass1st - 14/6/10 at 08:03 PM

Yes, I do have a pressure regulator so will try a few tests changing the pressure to see if I can fix it. May invest in a swirl pot anyway. Any recommendations?

RichardK - 14/6/10 at 08:06 PM

Adding a swirl pot will certainlay do no harm. Seems like a sensible next move.

Cheers

Rich

ashg - 14/6/10 at 10:52 PM

do you have a big or small filter. i had the same issue and changing the filter for a little tiny one solved it

cliftyhanger - 15/6/10 at 06:20 AM

Look at the exhaust when it happens, if you get black smoke it is over-fuelling/choking up. Changing fuel pressure has little (ie no) effect. Been there, done that. But you can drop it to 1 psi and see....
A swirl pot is going to require a second pump and all sorts, not really used in carb applications. The carb float chamber holds a significant amount of fuel, tun the pump off and see how far you can drive (I managed about 1/2 mile in mine)

NS Dev - 15/6/10 at 05:04 PM

ditto, no swirl pot needed with carbs really, prob flooding

Bass1st - 20/6/10 at 06:09 PM

I reduced the flow of fuel and also changed the main jets in my carbs from 40 to 35 - seems to have done the trick.