Increase Acceleration Enrichment to increase popping/burble exhaust sound?
08-28-2015, 01:39 PM
#1
Increase Acceleration Enrichment to increase popping/burble exhaust sound?
I have a stock Z06 and I love the off-throttle popping, gurgling, crackling noises. I want more of it and louder.
I plan to get a VaraRam intake and a set of longtube headers with high-flow catted xpipe for a little power increase.
From what I've read, the change from an hpipe to xpipe will reduce the popping sounds.
Would tuning be able to bring them back and increase them through increased acceleration enrichment?
From what I understand, this would increase the time in which fuel is injected after coming off the throttle, and as fuel is one of the causes of the popping, it would assist in creating the noise, at the cost of gas mileage.
I plan to get a VaraRam intake and a set of longtube headers with high-flow catted xpipe for a little power increase.
From what I've read, the change from an hpipe to xpipe will reduce the popping sounds.
Would tuning be able to bring them back and increase them through increased acceleration enrichment?
From what I understand, this would increase the time in which fuel is injected after coming off the throttle, and as fuel is one of the causes of the popping, it would assist in creating the noise, at the cost of gas mileage.
08-29-2015, 11:08 AM
#2
Drifting
I'm not super smart on GM/LS specific tuning terminology etc., but generally acceleration enrichment would be extra fueling 'added' on during times of rapid load/rpm changes when you quickly depress the accelerator pedal, etc.
I think what you're talking about is more Deceleration related. Many cars these days actually shut off fuel completely during deceleration in gear (engine braking). We have that feature but C5s have it disabled by default, so fuel is still being injected in decel. It's called DFCO or Decel Fuel cut off in efilive. Only thing I can think of to do here is increase VE values and reduce ignition timing in those super low-load cells where you will be during decel. There might be some other tricks or tips, I'm not super smart on GM-specific stuff, I've only been deep into speed density stuff with Megasquirt.
I think what you're talking about is more Deceleration related. Many cars these days actually shut off fuel completely during deceleration in gear (engine braking). We have that feature but C5s have it disabled by default, so fuel is still being injected in decel. It's called DFCO or Decel Fuel cut off in efilive. Only thing I can think of to do here is increase VE values and reduce ignition timing in those super low-load cells where you will be during decel. There might be some other tricks or tips, I'm not super smart on GM-specific stuff, I've only been deep into speed density stuff with Megasquirt.
08-29-2015, 07:29 PM
#3
Le Mans Master
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St. Jude Donor '13-'14-'15
The "motor boat" gurgling sound is often attributed to the stock "H" pipe Yes an X pipe will reduce this sound-----Another tuning trick to regain that gurgle sound is to delete the "DFCO" fueling in your tune----DFCO is the deceleration fuel cut-off---which is built into a stock tune---which shuts off the fuel during rapid deceleration--- Now if you delete the DFCO--- then upon rapid deceleration some fuel is still being injected into your engine---This fuel ends up in your exhaust and is burned up in your tailpipes--which in turn creates that popping and gurgle upon rapid deceleration
08-29-2015, 09:17 PM
#4
Drifting
The "motor boat" gurgling sound is often attributed to the stock "H" pipe Yes an X pipe will reduce this sound-----Another tuning trick to regain that gurgle sound is to delete the "DFCO" fueling in your tune----DFCO is the deceleration fuel cut-off---which is built into a stock tune---which shuts off the fuel during rapid deceleration--- Now if you delete the DFCO--- then upon rapid deceleration some fuel is still being injected into your engine---This fuel ends up in your exhaust and is burned up in your tailpipes--which in turn creates that popping and gurgle upon rapid deceleration
08-29-2015, 11:52 PM
#5
Safety Car
DFCO was disabled in my stock tune 2003 Z06. The tables are there, but you have to be over 10,000 rpm, below 0 MAP etc. for it to be active.. so it's effectively disabled. I believe I have read online that all Y bodies are this way, while other LS1 equipped cars had it turned on for whatever reason. Does this check?
Checked other stock files as well. It's set to enable at a coolant temp of 86F.
I have mine turned off. I never get any of that sound the OP speaks of.
Aaron, the numbers you mention are for clutch transitions. When shifting.
My car is an A4 BTW
Ron
Last edited by RonSSNova; 08-29-2015 at 11:55 PM.
08-30-2015, 09:52 AM
#6
Drifting
Yep you're right. EFIlive has a few separate RPM/MAP/TPS tables for normal operation to define it. I digged up an old datalog to confirm it as well.. wideband showing 22.0+ AFR on some long high rpm decels. Not really as aggressive or kicking in as much as I've seen on newer cars though.
Back to the OP, so yes, turning this off could be one way to get some extra burble/popping on decel. I messed around with such settings on my last car and it made it pop on decel, but it was also a very open catless exhaust. Reducing ignition timing in those decel low MAP cells will make it pop more too..basically you're just trying to not get complete combustion.
Back to the OP, so yes, turning this off could be one way to get some extra burble/popping on decel. I messed around with such settings on my last car and it made it pop on decel, but it was also a very open catless exhaust. Reducing ignition timing in those decel low MAP cells will make it pop more too..basically you're just trying to not get complete combustion.
Last edited by aaronc7; 08-30-2015 at 09:54 AM.
