A burble from exhaust - Camaro5 Chevy Camaro Forum / Camaro ZL1, SS and V6 Forums

FiLTHy PHiL SS/RS · 07-07-2009, 01:30 AM

Did a search, can't find anything of the following below....

Anyone having a funny noise/feeling with the L99 auto between speeds of 23 and 32 MPH.
Sort of like a Burbling sound and light on the gas pedal feeling like there is
some kind of misfire going on?
Wonder if it's just the Fuel management?

I can hear it at muffler and feel it in the slight adjusting of gas pedal...

If I lay into it she goes fine..Maybe un-ignited fumes in muffler?

LS3SSRS · 07-07-2009, 03:54 AM

if you were just taking it easy and drifting between those speeds it's probably the AFM cutting to 4 cylinders. im not sure about the L99's but i test drove a vortec max silverado with AFM and i could hear the exhaust note change a bit, but it also said on the display 4 cyl mode, then when u give it gas it switches and says 8 cyl mode. the camaro doesn't say anything on the display?

RickyTheStorm · 07-07-2009, 09:44 AM

Yep, experience it all the time - the trick is getting it to do it at 70 mph - it is the 4 cyl. mode. Seems normal to me, kind of makes the gas pedal vibrate too.

Sloppy Joe · 07-07-2009, 10:41 AM

Yep, hear and feel it too. Kind of gives you the feeling the trany is going into overdrive at 20 mph. If the AFM didn't drop cylinders below 50-60 mph, I don't think it would be an issue? So far, it's the only thing I don't like about the Auto.

camarossrs2150 · 07-07-2009, 03:54 PM

anybody else hear about 4 clicks in the trunk after starting .i hear it when i put it in reverse to back up out of driveway l99

y2jdmbfan · 07-07-2009, 04:00 PM

I hear a backfire/popping noise in my L99 w/ ~1100 miles on it when starting the car and sometimes when I take off fast trying to show off...So much for the showing off part when the car backfires...

Y2J

Rodrunner · 07-07-2009, 09:38 PM

I've found the L99 is in AFM mode far more than 8 cylinder. I can be in any gear and at only 1200 RPM's, and if not on the gas it'll go to 4 cylinders. Then, just a slight push of the throttle, not enough to get it to shift to 8 cylinders, gives a vibration because the 4 cylinders just can't handle the pull. Best to just use the M shifter position, and it will never go to AFM, 4 cylinders. Mine never goes to 4 cylinders when in M. If you're previously in Drive and shift to M, AFM is still active. You must hit the "-" paddle to get it to downshift, from then on it's disabled.

FiLTHy PHiL SS/RS · 07-08-2009, 01:32 AM

Quote:

Originally Posted by LS3SSRS

if you were just taking it easy and drifting between those speeds it's probably the AFM cutting to 4 cylinders. im not sure about the L99's but i test drove a vortec max silverado with AFM and i could hear the exhaust note change a bit, but it also said on the display 4 cyl mode, then when u give it gas it switches and says 8 cyl mode. the camaro doesn't say anything on the display?

Quote:

Originally Posted by RickyTheStorm

Yep, experience it all the time - the trick is getting it to do it at 70 mph - it is the 4 cyl. mode. Seems normal to me, kind of makes the gas pedal vibrate too.

Quote:

Originally Posted by Sloppy Joe

Yep, hear and feel it too. Kind of gives you the feeling the trany is going into overdrive at 20 mph. If the AFM didn't drop cylinders below 50-60 mph, I don't it would be an issue? So far, it's the only thing I don't like about the Auto.

Quote:

Originally Posted by Rodrunner

I've found the L99 is in AFM mode far more than 8 cylinder. I can be in any gear and at only 1200 RPM's, and if not on the gas it'll go to 4 cylinders. Then, just a slight push of the throttle, not enough to get it to shift to 8 cylinders, gives a vibration because the 4 cylinders just can't handle the pull. Best to just use the M shifter position, and it will never go to AFM, 4 cylinders. Mine never goes to 4 cylinders when in M. If you're previously in Drive and shift to M, AFM is still active. You must hit the "-" paddle to get it to downshift, from then on it's disabled.

Great info, was afraid it was just me, I will check it out in Manual mode..
Thanks

FiLTHy PHiL SS/RS · 07-08-2009, 01:38 AM

Quote:

Originally Posted by camarossrs2150

anybody else hear about 4 clicks in the trunk after starting .i hear it when i put it in reverse to back up out of driveway l99

I did notice this clicking when I first got it...
Not sure if its some kind of fuel pump in tank or ABS testing routine?!

I was hoping it was the sound of a 2 speed rear end getting ready to Launch me into the back seat....

07-07-2009, 01:30 AM	#1
FiLTHy PHiL SS/RS Me likes Blue Drives: 1968 Camaro RS, 2010 SS/RS IBM Join Date: May 2009 Location: Manch Vegas NH Posts: 738 View My Garage	A burble from exhaust Did a search, can't find anything of the following below.... Anyone having a funny noise/feeling with the L99 auto between speeds of 23 and 32 MPH. Sort of like a Burbling sound and light on the gas pedal feeling like there is some kind of misfire going on? Wonder if it's just the Fuel management? I can hear it at muffler and feel it in the slight adjusting of gas pedal... If I lay into it she goes fine..Maybe un-ignited fumes in muffler? __________________ Ordered 4/25/09 Born on 6/11/09 Delivered 6/26 Picked up 6/27 2SS/RS IBM, Body Matched Ground Effects, Sunroof, Silver riser stripes, ADM CAI, Noweeds exhaust, Catch Can (Blue). Don't care what color. as long as it's Imperial Blue Metalic! Own 68 Camaro RS 327 LeMans Blue, 2002 Vet Electron Blue

07-07-2009, 03:54 AM	#2
LS3SSRS Drives: 2010 IBM SS/RS Join Date: Oct 2008 Location: Edmonton, Alberta Posts: 805	if you were just taking it easy and drifting between those speeds it's probably the AFM cutting to 4 cylinders. im not sure about the L99's but i test drove a vortec max silverado with AFM and i could hear the exhaust note change a bit, but it also said on the display 4 cyl mode, then when u give it gas it switches and says 8 cyl mode. the camaro doesn't say anything on the display? __________________ sold 2010 2SS/RS, 6spd manual, imperial blue metallic w/black leather Blacked out tail/signal lights, 5% rear tint, 20% sides, Dynomax Bullet mufflers, Barton short throw shifter, Clear Image offroad downpipes

07-07-2009, 09:44 AM	#3
RickyTheStorm Drives: '10 Camaro 2SS,04 Colorado,06 ZX6R Join Date: May 2008 Location: Chambersburg, PA Posts: 524 View My Garage	Yep, experience it all the time - the trick is getting it to do it at 70 mph - it is the 4 cyl. mode. Seems normal to me, kind of makes the gas pedal vibrate too. __________________ Vararam CAI, ARH Headers, Flowmaster Exhaust, Nitto NT555Rs, Custom CAM and Tune - 11.981 @ 116.27 IOM - 2SS/RS - Auto - IAP - Sunroof - Ordered 10/13 (#7 at dealer) 3000(accepted to production ): 4/19/09 3300 (scheduled for prod ): 5/11/09 3400 (broadcast ): 5/16/09 3800 (produced ): 5/22/09 4150 (invoiced ): 6/01/09 4200 (shipped ): 6/01/09 5000 (at dealer ): 6/12/09 6000 (delivery to me ): 6/12/09

07-07-2009, 10:41 AM	#4
Sloppy Joe Drives: 2SS RJT Join Date: Mar 2009 Location: Mexico, Missouri Posts: 136	Yep, hear and feel it too. Kind of gives you the feeling the trany is going into overdrive at 20 mph. If the AFM didn't drop cylinders below 50-60 mph, I don't think it would be an issue? So far, it's the only thing I don't like about the Auto. Last edited by Sloppy Joe; 07-08-2009 at 02:12 PM.

07-07-2009, 03:54 PM	#5
camarossrs2150 Drives: abm2ssrs Join Date: Apr 2009 Location: still out of my mind Posts: 2,095	anybody else hear about 4 clicks in the trunk after starting .i hear it when i put it in reverse to back up out of driveway l99 __________________ [SIGPIC]

07-07-2009, 04:00 PM	#6
y2jdmbfan Drives: 2013 IOM ZL1 Join Date: Feb 2009 Location: Lemont, IL Posts: 106	I hear a backfire/popping noise in my L99 w/ ~1100 miles on it when starting the car and sometimes when I take off fast trying to show off...So much for the showing off part when the car backfires... Y2J

07-07-2009, 09:38 PM	#7
Rodrunner Senior Member Drives: 2010 SS/RS, '06 350Z Join Date: Oct 2008 Location: So. Maryland Posts: 2,333	I've found the L99 is in AFM mode far more than 8 cylinder. I can be in any gear and at only 1200 RPM's, and if not on the gas it'll go to 4 cylinders. Then, just a slight push of the throttle, not enough to get it to shift to 8 cylinders, gives a vibration because the 4 cylinders just can't handle the pull. Best to just use the M shifter position, and it will never go to AFM, 4 cylinders. Mine never goes to 4 cylinders when in M. If you're previously in Drive and shift to M, AFM is still active. You must hit the "-" paddle to get it to downshift, from then on it's disabled. __________________ 2SS/RS - Black/Black - CGM Rally Stripes - Auto - VIN 10171

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