bulk rich on gear change

[smidge]

is there any way to prevent the ECU dumping a whole heap of fuel in when the throttle is snapped shut on a gear change?

i understand why its happening, reversion of whatever its called, but is there a way to dampen it so it doesn't send a heap of air through the AFM which then tells the ECU there is stacks of air so put in stacks of fuel, which it does, which then covers the back of my hatch in black soot?!?!

plumb back dump valve? atmos dump valve?

 

[Ed]

This shouldn't happen, as the ECU should enter over-run when TPS is closed. What is the throttle closed voltage?

 

[smidge]

i'll check it now, is there set resistance that the TPS should be at? or a TPS switch as with some other cars i've had? where it sends the ECU either an open or closed signal aside from the position voltage

with one prob grounded, i get a reading of 9v one pin, that drops to 0v when i move the throttle and the supercharger relay clicks

on the other pin, i get 9v that goes up to 12v when i move the throttle

that seems a bit weird eh! is that where i should measure from? the other option is to measure from where the wire goes into the ECU where i've currently got the wideband spliced into

on the wideband log it shows that it sits around .4volts when the throttle is closed

 

[Ed]

the 0.4V is correct. You need to find another method to check over run is working correctly, but its not so easy, can you get an old fashioned spark plug tester? Rev the engine with it connected and watch the spark, rev to 3K and let go the spark should stop until around 1600 ish rpm where the spark will start again perhaps see if you can log an injector or something to see that happening?

 

[smidge]

Ed i can tell from the wideband that the injectors are being cut on over run, as it will go 20:1 then just display lean, this includes when going down a steep hill with the foot off the throttle, or are the two things not related? maybe my idle up or idle settings are wrong so its still got too much fuel in there?

my theory was that all that extra FMIC piping etc is causing the air that stops at the throttle to get spat back out past the turbo (making the chat chat chat sound) and then the AFM which reads the air on the way back out then dumps fuel in, although if the TPS is showing .4 volts then it shouldn't be throwing fuel in

wow.. lots to learn eh? wanna start calling me grasshopper with all this ECU stuff???

 

[Ed]

Ed i can tell from the wideband that the injectors are being cut on over run, as it will go 20:1 then just display lean, this includes when going down a steep hill with the foot off the throttle, or are the two things not related? maybe my idle up or idle settings are wrong so its still got too much fuel in there?

Ok that's fine then, thats exactly what I am talking about.

my theory was that all that extra FMIC piping etc is causing the air that stops at the throttle to get spat back out past the turbo (making the chat chat chat sound) and then the AFM which reads the air on the way back out then dumps fuel in, although if the TPS is showing .4 volts then it shouldn't be throwing fuel in

wow.. lots to learn eh? wanna start calling me grasshopper with all this ECU stuff???

Do you have a dump valve fitted? You could try one with a stronger spring. Sounds like it may be opening too soon when you have not yet told the ecu via tps your in over run.

I'm surprised its anywhere near bad enough however to cover the car in soot.

 

[smidge]

yeah that soot could have been my bulk rich situation up in the top end but i didn't think i booted it often enough to do that

no dump valve, thinking of putting one on anyway though to quieten it down cause the flutter out through my air filter is really bloody loud!

 

[Ed]

Its not a bad idea tbh. Helps prevent turbine stall/surging, then the trick is to change gear fast enough that you have not vented all the air out to the atmosphere

lol

 

[smidge]

might get a hybrid version i think! something like this...

http://www.gfb.com.au/index.php?par...cts&sub_option=bovs&sub_sub_option=stealth_fx


then i can adjust the noise/atmos/plumb back amount...

 

[Ed]

Should do the trick. Pretty expensive tho!

 

[smidge]

they sponsor us

 

[Baz]

I'm pretty sure my car does this aswell man. . .If you want to quiten the intake replumb the resonator(black box with the 3 vacuum connections on it)I put it back in mine for road use