2019 stingray.
A8
corsa off-road x pipe
awe track exhaust
gm performance air intake

i never paid any attention to the speed in which the car coasts/decelerates when I let off the throttle at a normal speed, let’s say 35-40mph.

in November I put on the BMS racing performance air filter, designed for the GM performance air intake....

I started driving around allowing the car to relearn the air flow, and I thought to myself it seemed pretty slow to drop speed/rpm when letting off the loud pedal around 40mph, it’s happy to drive itself in the 20mph range for a bit... I also noticed the the pops and bangs coming out of my straight through exhaust had calmed down a bit.

what could have changed, or did I never notice it before??? Where did some of my pops and bangs go when I changed that air filter?

The thing is, I don’t remember myself coasting or paying attention to the deceleration before changing that air filter, what do your cars do?!? Is this normal. Did I lose pops and bangs cos I’m putting more air through now?

Thanks for your upcoming explanations!

 

This is the explanation a car guy at work sent me, to explain the loss of some pops and bangs on decel. Which makes sense ...

 

Any thing on the DIC that says Performance Mode or something like that? If you are being playful with the throttle and accelerating hard, the car thinks you want to race. I call it puppy mode. It will hold the RPMs up higher than normal as the higher RPMs allow the engine to respond faster to your heavy foot. When you don't agitate the throttle for 10 seconds or so, it drops out of PM and the RPMs fall normally.

Elmer

 

This is all outside of performance shift
i haven’t driven it in a playful manor yet lol

this is all sensible driving around town under 50pmh without any spirited accelerating

 

So it’s all starting to make sense to me know that as a result of improving/increasing the airflow the (what was stock) throttle body is taking longer to close. Therefore my engine is burning the previously unburnt fuel, which is resulting in less pops and bangs


side note - last night put in the soler powered throttle body. No change to my previous findings with decel and loss of pops and bangs, but wow does it have more sensitive throttle acceleration!

today the throttle controller goes on (but it’ll rain)

 

The BMS air filter tricks the ECU into thinking there is approximately 8-10% less air coming into the engine. On an untuned car, this moves the Airmass calculation around and the ECU uses Airmass to determine torque and control spark as well as fueling. You will notice slightly different behavior by running the filter untuned. Same as any aftermarket intake that tricks the ECU into seeing less airmass. The effect at WOT though means a more optimal fuel ratio for power and more spark/boost on the Z06's.

 

Thank you for the explanation! I would have thought increasing the size of the air filter would allow more air! Boy was I wrong!?

so, was it a good thing for me to swap from the GM performance air filter to this BMS one? What you wrote didn’t sound like a positive!...

and I lost my pops and bangs!

 

It does allow more airflow, but the opening of the BMS filter is larger where it faces the MAF. The engine pulls in the same amount of air at idle, but doing so though a larger hole reduces air velocity. Air velocity directly affects the MAF sensors reading since thats exactly how a Mass Air Flow sensor works. This is why the airmass calculations change.

As for good vs bad. I personally did not like the BMS air filter in my GM Performance Intake but I am tuned. Tune vs Tune I found zero advantage to the BMS filter vs the GM Performance filter. Again, when you tune for both as I did there is no advantage. I want to make that clear so that no one thinks I am bad mouthing a product. These were just my own findings.

If you are UNTUNED the BMS filter will lean the Air Fuel out at full throttle and you could potentially pick up a little bit of power. The ECU will eventually correct for some of that but since your airmass reading is lower you COULD manage to have less overall fuel and slightly more timing at full throttle. It boils down to the airmass calculations the ECU to reference how much spark to use. And then the fueling is tricked by MAF seeing less air so it adds less fuel. The ECU will make up for some of the fueling part with its long term fuel trims but overall STOCK tuned Z06 cars will benefit at WOT with the BMS air filters in either the stock intake box or the GM performance intake box.

But my last thought is, the GM Performance Filter vs the BMS. Is the small amount of power you can't feel worth the drive-ability change and the loss of exhaust sounds you like? That is the real question you need to answer.

P.S. I have a slightly used BMS air filter for the GM Performance Intake if anyone wants to buy one half price. I'll sell it for $50 shipped. I'm keeping the GM filter for the reasons I stated above.

 

Thank you very much for your time and knowledge..

I think the pros and cons and my findings are going to result in the performance GM air filter going back in.

I have the Soler potted throttle body now and throttle controller. So these enhancements combined with the GM performance intake... and the return of my pops and bangs will give me all I need.

the difference of the BMS filter wasn’t worth anything to me without my bangs!

thank you once again you have been incredibly helpful.