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Popping on overrun
Yazza54 - 25/11/11 at 06:00 PM

If the pop n bang on overrun is caused by unburnt fuel injected on zero throttle am I right in thinking if one had a motorcycle and access to mapping software one could slightly increase the fuel on 0% throttle to get a bit more popping on overrun?


Not that I'm going to do this officer

Oh no



AntonUK - 25/11/11 at 06:09 PM

when i ran carbs and just a megajolt, we have been known to back the ignition timing back to 5 or 6 deg in the overun area of the map... made loads more pop's and bangs...

exhaust mainfold gasket didnt last long tho...

Used Offroad only of course


steve m - 25/11/11 at 06:13 PM

Mine pops and bangs on the overun,
To me, its pretty annoying!


Yazza54 - 25/11/11 at 06:30 PM

quote:
Originally posted by steve m
Mine pops and bangs on the overun,
To me, its pretty annoying!


Are you a 21 yr old hooligan though?


Mr C - 25/11/11 at 06:49 PM

I'm hoping for a few pops and bangs on the overun as well, just to encourage it a little an aftermarket dump valve is fitted, the CAT has gone awol and the exhaust ends about 12 inches from the turbo, all in the name of refinement, quality and class.


Autosri - 25/11/11 at 06:55 PM

Holes in exhausts cause bangs an pops to


steve m - 25/11/11 at 07:16 PM

"Are you a 21 yr old hooligan though? "

Errrr, no !


fatbaldbloke - 25/11/11 at 08:46 PM

Popping and banging is usually caused by the mixture on overrun being too lean. It's too lean to burn in the engine so the unburnt fuel gathers in the exhaust and ...bang. If you have a banging exhaust and don't want one, then add a little fuel on overrun. If you don't have pops and bangs and for some reason you want them, which will blow the insides of your silencer out as well, you may have to add a little fuel if you have zero fuel on overrun, or weaken the mixture if you have it combusting well. It could be either.


omega0684 - 25/11/11 at 08:49 PM

why would you want popping on over run, just to make the car sound better by wasting more fuel?


Yazza54 - 25/11/11 at 09:00 PM

Just experimenting!

Funny that I had heard it could be caused by too rich or too lean on overrun. It already does it a little... I leave it alone for now.


TAZZMAXX - 25/11/11 at 09:04 PM

Have a look at this, it's an interesting take on what's being discussed here as well as being bloody funny. Enjoy.

http://www.xtranormal.com/watch/6863749/performance-diesel-vs-vxr8


sky12042 - 25/11/11 at 09:06 PM

I heard it was also caused by a leak in the exhaust so on overun the unburnt fuel mixes with the oxigen coming into the exhaust and once it reaches the correct ratio it will pop.

Andy


Mr C - 25/11/11 at 09:35 PM

quote:
Originally posted by TAZZMAXX
Have a look at this, it's an interesting take on what's being discussed here as well as being bloody funny. Enjoy.

http://www.xtranormal.com/watch/6863749/performance-diesel-vs-vxr8


Note to self, give up yoga and get a black V8


matt_gsxr - 25/11/11 at 09:44 PM

It is definitely caused by weak mixtures on overrun.


MakeEverything - 25/11/11 at 10:27 PM

When I drove mine to the mot station, I got half way and had to stop because I had 3foot flames out of mine on overrun. A quick change of overrun settins sored it though, and now it will only do it for 1.5 seconds!!


Yazza54 - 25/11/11 at 11:20 PM

quote:
Originally posted by MakeEverything
When I drove mine to the mot station, I got half way and had to stop because I had 3foot flames out of mine on overrun. A quick change of overrun settins sored it though, and now it will only do it for 1.5 seconds!!



Weaker or richer?


MakeEverything - 26/11/11 at 12:46 AM

quote:
Originally posted by Yazza54
quote:
Originally posted by MakeEverything
When I drove mine to the mot station, I got half way and had to stop because I had 3foot flames out of mine on overrun. A quick change of overrun settins sored it though, and now it will only do it for 1.5 seconds!!



Weaker or richer?


Neither, I can adjust the overrun fuel cut timings in mega squirt as well as the amount of fuel.


fatbaldbloke - 27/11/11 at 07:27 PM

quote:

Neither, I can adjust the overrun fuel cut timings in mega squirt as well as the amount of fuel.



What this doing is creating a short period of weak mixture as it's cutting the fuelling.