SS Automatic Heads up

[TomServo]

If you turn off the AFM does it gain back the 26HP??

[BrianGriffin78]

I have 3400 miles on my 2SS, and have not heard any noises, except when the window is open, but that is just the wind hitting the open seams, so it's normal. My car is running even better now, imo.

[Ultimate Performance]

Chevyman...tell the dealership we will buy the car for a dollar. Really

[Supermans]

Originally Posted by TomServo

If you turn off the AFM does it gain back the 26HP??

no..

[SGOS252382]

What's your exhaust setup?
When my car was 100% stock, it was very quiet all the time.

Now I have the GMPP off road axle back and my car is tuned, I get an exhaust sound on the transition from 4 to 8 cylinders. But it seems to be mostly related to the aggressive transmission tune.
And I had a buddy from work take a ride in my car today and he said it sounded great (and he never picked up on the AFM sound). He was absolutely blown away by the car's peformance.

When crusing at 60-80mph its still very quiet when cruising. The only time I get a noise is when I get on the gas and I can hear the AFM transition. But other than that I have no drone or vibration. But with a full exhaust setup (headers, high flow cats, exhaust) I could definately see the AFM setup becoming a annoying noise.

The next time I get my car tuned, I will most likely have the AFM turned off.

[PQ]

Originally Posted by TomServo

If you turn off the AFM does it gain back the 26HP??

....................



I've not heard the noise the way it's described. Of course I'm not sure I've had the windows up and the radio off yet.

I do still hear the tranny 'whine' at very low speeds if I listen closely. But I think it's normal.

[ZombieEatsYou]

No obnoxious noise with me either. Just went over 1K miles stock everything.

[patriotpa]

You hear a resonance? I have a 1SS L99 and I hear NO difference. Quiet as can be until I romp on the gas. Weird.

[Missile Man]

1k mile and no exhaust noise. Turned off the radio and A/C the other day and was super quiet. Installing a SLP Loudmouth II this weekend, we'll see if there is any noticeable change.

[muSScle]

I had the GMPP (axle back, not off-road) system put on Friday, much more noticeable drone at low speeds 20-30 mph.... also around 55-60 cruising.... definately the AFM..... the CAI (Hennessey) seems louder than the exhuast when standing on.... pretty quiet setup.... auto trans, 600 miles.....

[Shadowmind]

I definitely feel the bog down in mine. This seems to be a problem with the Auto not downshifting from 4th to 3rd or 2nd at low rev/slower speeds. This is a problem that has been in the L99 since it came out for the Corvette. The 'slows' or bog down basically happens when you slow down from say... 40, to 25 in a short period of time. The tranny 'should' downshift to 3rd gear, but it doesn't. It stays in 4th, and you feel the car running 'sluggish'. If you give a quick gun, all 8 pop in and it doesn't feel as sluggy, but then again, a quick pop will boost you 5-10 mph in a matter of micro-seconds. :P

Your vibration problem is probably coming from something loose in the engine housing, or maybe in front of the cats/headers. The bog down would emphasize that vibration a lot.

[d69chris]

Have no had an issue with my 2SS L99. Too quiet with stock exhaust, just had the Corsa installed and I like it. A little more noise at idle, but comes to life when you get on it. Wll listen for the drone at freeway speed when the AFM kicks in. On surface street at 50mph and 1600rpm, nothing.

[paulv7260]

Originally Posted by Shadowmind

I definitely feel the bog down in mine. This seems to be a problem with the Auto not downshifting from 4th to 3rd or 2nd at low rev/slower speeds. This is a problem that has been in the L99 since it came out for the Corvette. The 'slows' or bog down basically happens when you slow down from say... 40, to 25 in a short period of time. The tranny 'should' downshift to 3rd gear, but it doesn't. It stays in 4th, and you feel the car running 'sluggish'. If you give a quick gun, all 8 pop in and it doesn't feel as sluggy, but then again, a quick pop will boost you 5-10 mph in a matter of micro-seconds. :P

Your vibration problem is probably coming from something loose in the engine housing, or maybe in front of the cats/headers. The bog down would emphasize that vibration a lot.

Exactly! This has been my experience as well (I have no problem when crusing at highway speeds). Mechanic did a test drive. Said his Camaro does the same thing and said we would have to wait for a new program IF GM decides to do one.

First time my wife heard it she thought the noise was the vibration coming from another car's sub-woofers!!

I've learned to live with it (the noise AND the wife). J/K.

I tried an experiment. When slowing down shift into manual mode. Then I tap shifted UP. When I did this it said "shift denied" so I tap shifted DOWN and the gear showed M5. This tells me that the shift was denied because I was already in 6th gear but at the slower speed (what I call impulse power speed - 20 - 30 MPH @ <2000 RPM ) the tranny should have at least stepped down to M4 (IMO).

Is this AFM or is it the tranny program or is it both? I don't know.

[ssdavidw]

Almost 400 miles on mine and haven't noticed any noises I find annoying except for a piece of trim that seems to be loose and rubbing.

Car seems smooth, powerful and quiet.