G37 Sedan

Pop/Slam when taking foot off the gas

Old Jun 13, 2009 | 01:42 PM
  #1  
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g37brad
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Pop/Slam when taking foot off the gas

Hey guys...Since the car is still new and I floored it many times on my test drive...I've tried to just drive it gently til I hit 1k miles, since I raped her in the begining and feel bad..haha

Anyways...I noticed a few things...For example in order to make sure it doesnt go over 4k rpm or so, I usually hold the gas down, then sorta take my foot off...Usually when I do this the car will seem to make an obvious pop/slam sound...Not sure what's causing that. Should I not be taking my foot off the gas? Or just give it constant gas?

I also notice the same thing when I'm accelerating to lets say 30mph speed limit and just take my foot off the gas and let it coast, I get the same slam/pop sort of thing.

Thanks.
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Old Jun 13, 2009 | 01:57 PM
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From: Houston, TX
Sounds like a backfire? Take it to the dealer.
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Old Jun 13, 2009 | 02:20 PM
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Are you applying gradual pressure to the throttle or stomping down on it?
I have seen people before who drive like the throttle is a on / off switch, and it is very hard on the components and provides very poor fuel mileage.

The pop / slam you describe is a sound? , or actually the drivetrain trying to determine the proper shift procedure. If the engine seems to race and then the car lurches during a shift, the transmission is still trying to determine the proper shift engagement that your driver tendencies have promoted.
The more you are on /off the throttle versus making precise and gradual adjustments in throttle position, the stranger the shift procedure will tend to be.
The programming of the Transmission CPU tries to adapt shift procedures to meet with the "learned" drivers behavior, so the more erratic the driver, the harder it is for the transmission to learn an appropriate pattern.
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Old Jun 13, 2009 | 09:20 PM
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g37brad
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Originally Posted by dbg37
Are you applying gradual pressure to the throttle or stomping down on it?
I have seen people before who drive like the throttle is a on / off switch, and it is very hard on the components and provides very poor fuel mileage.

The pop / slam you describe is a sound? , or actually the drivetrain trying to determine the proper shift procedure. If the engine seems to race and then the car lurches during a shift, the transmission is still trying to determine the proper shift engagement that your driver tendencies have promoted.
The more you are on /off the throttle versus making precise and gradual adjustments in throttle position, the stranger the shift procedure will tend to be.
The programming of the Transmission CPU tries to adapt shift procedures to meet with the "learned" drivers behavior, so the more erratic the driver, the harder it is for the transmission to learn an appropriate pattern.
Yeah, I drive like you said. I treat it sort of like an on / off switch. Just give it gas, and take my foot off. Should I be doing it differently?

Also...sometimes I'll hold the gas down gradually and the rpms might be at like 2k and the car is like WTF and sorta doesnt know what to do. Am I just going too easy on it, during break in? I've already floored it during the test drive, but trying to really baby it for a few hundred miles. When I accelerate really slow, the transmission just seems confused and just suddenly shifts or just jumps all over. I guess because it doesnt know wtf is going on. Usually when the rpms are lingering about 2k and im not giving it alot of gas...
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Old Jun 14, 2009 | 12:08 AM
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From: Reno, NV
g37brad, sounds like a symptom of "bump car" driving. Like what you have mentioned, the gas pedal in this case was subjected to on & off scenario.

Artful utilization of the throttle system is about thinking that the gas pedal like a sensitive variable switch. A field where this technique is employed to its highest degree is on motorcycle throttle control where it goes beyond just propulsion purposes, but to cornering management, suspension stabilizing aspect, and curve entry-&-exit velocity control.

Like what dbg37 articulated, the pop/slam effect is from the AT transmission changing gears likely erratically due to accelerator pedal input.
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Old Jun 14, 2009 | 11:46 AM
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From: t.dot.O
yeeep. the computer on board needs to figure out if you want to floor it or if you just want a little gas, stop confusing her and drive properly !
.
haha
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