Car feels slow when fuel is less than half full

rfcoolz · 10-03-2015, 10:29 PM

Hey guys! I don't know if its just in my head or not, but my car feels way slower when fuel is less than half full even after driving 30+ miles. Sports mode with DS still can't satisfy me. Every after filling up full (I always do V-Power), I can feel my neck hitting the headrest hard and OH GOD, its like I fell in love with my car all over again. It happened consistently after more than 10 fill-ups.

Any idea how to fix this? Maybe it is something to do with fuel pressure?

Thanks!

FSociety · 10-04-2015, 12:53 AM

Try Redline fuel-cleaner or switching gas like Valero, Costco, BP and see

DXL XLR8 · 10-04-2015, 01:26 AM

Mine does the same thing. Thought it was all in my head.

wolves · 10-04-2015, 02:13 AM

I just hit 60k+ miles and this has started happening. Thought I was losing it but I swear I can feel the difference and also fill up with Shell regularly. It's not as noticeable with Chevron and I wonder if it's the difference in fuel additives.

Pro · 10-04-2015, 02:36 PM

Same here. I always fill Vpower.

Wonder if its because the octane boosting additives are a different density and are sucked up by the fuel pump first?

Fraggy · 10-04-2015, 09:54 PM

I swear I noticed this too but thought it was all in my head. It's really noticeable under a 1/4 tank.

oceanview · 10-05-2015, 03:33 AM

Could be that you have water in the gas-tank. Have it checked with your dealer.
Easiest way is to completely empty the tank (not by driving, but in the garage)
Then refill with normal gasoline.

Sometimes this happens with the expensive gasoline brands like V-Power. Because V-Power is more expensive, they sell only low quantities compared to regular gasoline. The expensive V-Power then sits in the tank of the gas station for too long and moisture water mixes up in the gas station tank. Once a while a nerd (like us) drives by and instead of high quality gasoline you get junk with too much water.

Again, just my guessing and a possible explanation. However chance is high, that the problem comes from the gas tank.

Another thing causing this problem could also be, that the ventilation of the gas-tank is blocked. If you open the gasoline refill cover, when you want to refill, can you hear air get sucked in?
If the ventilation is blocked, a vacuum will occur during lowering the gasoline level. The higher the vacuum in the tank the less gasoline will be pumped to the engine.

ErkanTR16 · 10-05-2015, 04:03 AM

Use Shell.

rfcoolz · 10-05-2015, 07:52 AM

Quote:

Originally Posted by oceanview

Could be that you have water in the gas-tank. Have it checked with your dealer.
Easiest way is to completely empty the tank (not by driving, but in the garage)
Then refill with normal gasoline.

Sometimes this happens with the expensive gasoline brands like V-Power. Because V-Power is more expensive, they sell only low quantities compared to regular gasoline. The expensive V-Power then sits in the tank of the gas station for too long and moisture water mixes up in the gas station tank. Once a while a nerd (like us) drives by and instead of high quality gasoline you get junk with too much water.

Again, just my guessing and a possible explanation. However chance is high, that the problem comes from the gas tank.

Another thing causing this problem could also be, that the ventilation of the gas-tank is blocked. If you open the gasoline refill cover, when you want to refill, can you hear air get sucked in?
If the ventilation is blocked, a vacuum will occur during lowering the gasoline level. The higher the vacuum in the tank the less gasoline will be pumped to the engine.

Actually your explanation makes sense to me. Do you know any way to empty the whole gas tank? Is it by using something like shaker siphon? Or could it only be done through dealership?

Thanks for your response!

BeachsideF30 · 10-05-2015, 08:39 AM

I notice this below 1/4 tank too. esp down to 1/8th. Second i fill back up with chevron 93 its back to normal

DXL XLR8 · 10-05-2015, 08:43 AM

To be honest, I actually enjoy this. It gives me a reason to keep the tank at least half full and the nice power boost after each fill up is nice

oceanview · 10-05-2015, 10:12 AM

Quote:

Originally Posted by rfcoolz

Actually your explanation makes sense to me. Do you know any way to empty the whole gas tank? Is it by using something like shaker siphon? Or could it only be done through dealership?

Thanks for your response!

Sorry don't know how they recommend to empty it.
The fuel tank has two chambers.
If water is the cause, probably only a complete dismount and drying the fuel tank makes sense.
http://www.realoem.com/bmw/enUS/show...diagId=16_0872

But again, just guessing that water could be the problem. I would go to the dealer and they need to look at it.

rfcoolz · 10-05-2015, 10:32 AM

Quote:

Originally Posted by oceanview

Sorry don't know how they recommend to empty it.
The fuel tank has two chambers.
If water is the cause, probably only a complete dismount and drying the fuel tank makes sense.
http://www.realoem.com/bmw/enUS/show...diagId=16_0872

But again, just guessing that water could be the problem. I would go to the dealer and they need to look at it.

I think I'll give HEET water remover products a chance first, then if nothing changes I'll just bring it to the dealership.

smithf80 · 10-05-2015, 11:04 AM

Funny I just hit a little less than 1/4 last night and I thought my car was lacking some pep...

rfcoolz · 10-05-2015, 11:31 AM

Quote:

Originally Posted by smithf32

Funny I just hit a little less than 1/4 last night and I thought my car was lacking some pep...

Glad to know I'm not alone! So I guess its not water issue and more like a model specific problem since it affects tons of other n26/20 owners.

FSociety · 10-05-2015, 12:43 PM

I agree car feels faster when gas is half tank or more, preferably likes full tank anyone agrees?

And gas brand doesn't matter because I always switch after 3 tanks with Shell, Valero, Costco, BP, 76.

Ganxxta · 10-05-2015, 02:52 PM

Hm I didn't notice that, maybe because my tank is always empty real quick?

I'm always using 102octan RON, no idea whats that in US AKI.
Without ethanol, so they claim.

CalCarNut · 10-05-2015, 04:22 PM

You'd think at 1/2 full, the car would feel faster (50lbs less wait to be pulling).

I haven't noticed it in my car but since it's under 1/2 a tank now, I'll give it a few blasts and then go fill it up and see if my butt meter agrees with those here.

rfcoolz · 10-05-2015, 05:48 PM

Quote:

Originally Posted by SoCalDave

You'd think at 1/2 full, the car would feel faster (50lbs less wait to be pulling).

I haven't noticed it in my car but since it's under 1/2 a tank now, I'll give it a few blasts and then go fill it up and see if my butt meter agrees with those here.

Nope, what I mean is when it reach half full, the car feels slower than when its full (contrary to the popular belief that less fuel means lighter and faster car)

CalCarNut · 10-05-2015, 05:51 PM

I gotcha...(typo-wait s/b weight on my post)

Weird it feels slower. I'll have to check it out on mine.

BeachsideF30 · 10-05-2015, 08:09 PM

I can actually attest to this today, I had commented in this thread earlier today. After I commented on Lunch i went and filled the car up cause I was down to about 1/8th tank. And the throttle felt more responsive and lively after I filled up. I honestly don't believe it's placebo

Ganxxta · 10-06-2015, 02:19 PM

Maybe its one of those efficient dynamics things when the ECU recognizes that fuel is low it reduces power to use less fuel?

However this would only make some sense when the actual warning is already on and its almost empty, not at half mark.

10-03-2015, 10:29 PM	#1
rfcoolz Private First Class 39 Rep 183 Posts Drives: 2014 F30 328i xDrive Join Date: Feb 2015 Location: Philadelphia, PA iTrader: (0)	Car feels slow when fuel is less than half full Hey guys! I don't know if its just in my head or not, but my car feels way slower when fuel is less than half full even after driving 30+ miles. Sports mode with DS still can't satisfy me. Every after filling up full (I always do V-Power), I can feel my neck hitting the headrest hard and OH GOD, its like I fell in love with my car all over again. It happened consistently after more than 10 fill-ups. Any idea how to fix this? Maybe it is something to do with fuel pressure? Thanks!
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10-04-2015, 12:53 AM	#2
FSociety IG @bmwF9xG80 3813 Rep 7,593 Posts Drives: G80 M3, X4M, G07 X7m50 Join Date: Apr 2012 Location: NYC to NJ to Orlando FL iTrader: (3) Garage List 2023 BMW G80 M3 [0.00] 2020 BMW X4MC [0.00] 16' BMW X4 M40i [10.00] 06 Cadillac STS [0.00]	Try Redline fuel-cleaner or switching gas like Valero, Costco, BP and see __________________ 60-130mph 6.5s X4M #HCP 60-130mph 5.0s G80 M3 #OrlandoAutowerks Sauce IG: @bmwF9XG80
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10-04-2015, 01:26 AM	#3
DXL XLR8 Private First Class 47 Rep 101 Posts Drives: F30 Join Date: Jan 2013 Location: Nebraska iTrader: (0)	Mine does the same thing. Thought it was all in my head.
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10-04-2015, 02:13 AM	#4
wolves Second Lieutenant 29 Rep 261 Posts Drives: 2014 BMW 328i Join Date: Jul 2014 Location: United States iTrader: (0)	I just hit 60k+ miles and this has started happening. Thought I was losing it but I swear I can feel the difference and also fill up with Shell regularly. It's not as noticeable with Chevron and I wonder if it's the difference in fuel additives. __________________ 2014 BMW F30 328i - Base line 8AT, Alpine White, metallic black roof, Megan Racing CF decklid, CF canards, CF eyelids, CF rear diffuser, matte black kidney grills, gunsmoke tail lights/reflectors, VMR 721 Hyper Silver 19x9.5/19.x8.5, 5mm spacers all around, Bilstein B8s, Injen CAI, H&R Sport Springs, muffler-deleted quad pipe, 20% 3M rear tint, M Performance Pedals
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10-04-2015, 02:36 PM	#5
Pro Private 10 Rep 61 Posts Drives: F30 Join Date: Jul 2014 Location: NA iTrader: (0)	Same here. I always fill Vpower. Wonder if its because the octane boosting additives are a different density and are sucked up by the fuel pump first?
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10-04-2015, 09:54 PM	#6
Fraggy Brigadier General 193 Rep 3,469 Posts Drives: 2016 M3 Join Date: Jun 2005 Location: San Diego iTrader: (11)	I swear I noticed this too but thought it was all in my head. It's really noticeable under a 1/4 tank. __________________ 2016 Alpine White M3 (gone) 2019 Alfa Romeo Guilia (Totaled) 2020 Car-less 😁 (no more) 2020 M340
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10-05-2015, 03:33 AM	#7
oceanview Captain 207 Rep 603 Posts Drives: 335i F31 RWD Autom. Join Date: May 2013 Location: Switzerland iTrader: (0)	Could be that you have water in the gas-tank. Have it checked with your dealer. Easiest way is to completely empty the tank (not by driving, but in the garage) Then refill with normal gasoline. Sometimes this happens with the expensive gasoline brands like V-Power. Because V-Power is more expensive, they sell only low quantities compared to regular gasoline. The expensive V-Power then sits in the tank of the gas station for too long and moisture water mixes up in the gas station tank. Once a while a nerd (like us) drives by and instead of high quality gasoline you get junk with too much water. Again, just my guessing and a possible explanation. However chance is high, that the problem comes from the gas tank. Another thing causing this problem could also be, that the ventilation of the gas-tank is blocked. If you open the gasoline refill cover, when you want to refill, can you hear air get sucked in? If the ventilation is blocked, a vacuum will occur during lowering the gasoline level. The higher the vacuum in the tank the less gasoline will be pumped to the engine. __________________ 335i F31 RWD in SB \|\| Powertrain: Active Autowerke Flash Tune Stage 1 \| AA Charge Pipe \| AA FMIC \| GFB DV+ \| xHD Trans-Flash \| Quaife LSD \| Cyba 3.5" Carbon tips \|\| Chassis: 20" 405M \| Wiechers Strut Bar \| Rear M-Diffusor \|\| Brakes: 18" M-Perf Brake orange 370/345 \| EBC YellowStuff pads all around \|\| Various: LED bulbs: Fog-L. front \| Turn Signal f&r \| Brake L. \| Reverse L. \| Rear L. \| Rear Fog L.
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10-05-2015, 04:03 AM	#8
ErkanTR16 64-bit 598 Rep 814 Posts Drives: 2018 BMW 340i xDrive Join Date: Aug 2015 Location: Maryland iTrader: (0) Garage List 2018 BMW 340i xDrive [0.00]	Use Shell.
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10-05-2015, 08:39 AM	#10
BeachsideF30 Lieutenant 129 Rep 599 Posts Drives: E90--> E92-->F30 Join Date: Jun 2012 Location: FL iTrader: (0)	I notice this below 1/4 tank too. esp down to 1/8th. Second i fill back up with chevron 93 its back to normal
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10-05-2015, 08:43 AM	#11
DXL XLR8 Private First Class 47 Rep 101 Posts Drives: F30 Join Date: Jan 2013 Location: Nebraska iTrader: (0)	To be honest, I actually enjoy this. It gives me a reason to keep the tank at least half full and the nice power boost after each fill up is nice
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10-05-2015, 11:04 AM	#14
smithf80 Major General 2806 Rep 5,316 Posts Drives: G80 M3 6MT Join Date: Mar 2014 Location: Long Island, NY iTrader: (1) Garage List 2022 G20 330i [9.00] 2018 F80 M3 [9.75]	Funny I just hit a little less than 1/4 last night and I thought my car was lacking some pep... __________________ Scott, Partner Insight Automotive Consulting Click HERE for all discounted BMW New Car Pricing Click HERE for all BMW In Stock Inventory Specials Call/Text: 516-416-5481 Email: scott@insightautoconsulting.com
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10-05-2015, 12:43 PM	#16
FSociety IG @bmwF9xG80 3813 Rep 7,593 Posts Drives: G80 M3, X4M, G07 X7m50 Join Date: Apr 2012 Location: NYC to NJ to Orlando FL iTrader: (3) Garage List 2023 BMW G80 M3 [0.00] 2020 BMW X4MC [0.00] 16' BMW X4 M40i [10.00] 06 Cadillac STS [0.00]	I agree car feels faster when gas is half tank or more, preferably likes full tank anyone agrees? And gas brand doesn't matter because I always switch after 3 tanks with Shell, Valero, Costco, BP, 76. __________________ 60-130mph 6.5s X4M #HCP 60-130mph 5.0s G80 M3 #OrlandoAutowerks Sauce IG: @bmwF9XG80 Last edited by FSociety; 10-05-2015 at 01:04 PM..
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10-05-2015, 02:52 PM	#17
Ganxxta Second Lieutenant 85 Rep 280 Posts Drives: F32 4er Coupé Join Date: Oct 2013 Location: Germany iTrader: (0)	Hm I didn't notice that, maybe because my tank is always empty real quick? I'm always using 102octan RON, no idea whats that in US AKI. Without ethanol, so they claim.
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10-05-2015, 04:22 PM	#18
CalCarNut Brigadier General 1061 Rep 3,258 Posts Drives: 2015 F36 Jet Black Sport Line Join Date: Apr 2015 Location: Blue Skies iTrader: (0) Garage List 2012 BMW X3 [0.00] 2015 BMW 428i Gran ... [10.00] 1996 Chevrolet Impa ... [8.00]	You'd think at 1/2 full, the car would feel faster (50lbs less wait to be pulling). I haven't noticed it in my car but since it's under 1/2 a tank now, I'll give it a few blasts and then go fill it up and see if my butt meter agrees with those here. __________________ 2015 BMW F36 428i JetBlack. Sport Line Edition 25% 3M Tint\|
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10-05-2015, 05:51 PM	#20
CalCarNut Brigadier General 1061 Rep 3,258 Posts Drives: 2015 F36 Jet Black Sport Line Join Date: Apr 2015 Location: Blue Skies iTrader: (0) Garage List 2012 BMW X3 [0.00] 2015 BMW 428i Gran ... [10.00] 1996 Chevrolet Impa ... [8.00]	I gotcha...(typo-wait s/b weight on my post) Weird it feels slower. I'll have to check it out on mine. __________________ 2015 BMW F36 428i JetBlack. Sport Line Edition 25% 3M Tint\|
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10-05-2015, 08:09 PM	#21
BeachsideF30 Lieutenant 129 Rep 599 Posts Drives: E90--> E92-->F30 Join Date: Jun 2012 Location: FL iTrader: (0)	I can actually attest to this today, I had commented in this thread earlier today. After I commented on Lunch i went and filled the car up cause I was down to about 1/8th tank. And the throttle felt more responsive and lively after I filled up. I honestly don't believe it's placebo
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10-06-2015, 02:19 PM	#22
Ganxxta Second Lieutenant 85 Rep 280 Posts Drives: F32 4er Coupé Join Date: Oct 2013 Location: Germany iTrader: (0)	Maybe its one of those efficient dynamics things when the ECU recognizes that fuel is low it reduces power to use less fuel? However this would only make some sense when the actual warning is already on and its almost empty, not at half mark.
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