Fuel smell on cold starts

E92Carlos · 03-12-2015, 11:11 AM

Hello all , my car is full catless to the stock mufflers when i turn the car on in the morning i get a really strong gas smell from the exhaust and the car sputters for a few seconds and then its super smooth. Can this be a leaking injector ? Or does full catless just smell like that ?

mike@x-ph.com · 03-13-2015, 01:38 PM

Quote:

Originally Posted by E92Carlos

Hello all , my car is full catless to the stock mufflers when i turn the car on in the morning i get a really strong gas smell from the exhaust and the car sputters for a few seconds and then its super smooth. Can this be a leaking injector ? Or does full catless just smell like that ?

the smell is normal

LGCubana · 03-13-2015, 05:27 PM

Quote:

Originally Posted by E92Carlos

Hello all , my car is full catless to the stock mufflers when i turn the car on in the morning i get a really strong gas smell from the exhaust and the car sputters for a few seconds and then its super smooth. Can this be a leaking injector ? Or does full catless just smell like that ?

From the nature of your question, it sounds like you are brand spanking new to the bolt on. Do you gave either a JB4 or COBB AP ?

If not, you'll be getting error codes for the O2 sensors soon.

Bme30 · 03-14-2015, 11:16 AM

I disagree with both responses. Fuel smell on startup is not normal Catless or not! I'm full catless and have zero fuel smell.
I had very similar issue a while back and it was a leaky injector. How I found out which one I wanted till the next morning after the csr say all night. Started the car and let it idle for 20 seconds. Then pulled each plug till I found the wet one. Yes I had a wet plug! Leaky injector! Replaced and all smell and rough idle was gone.

j1gilles · 03-14-2015, 12:42 PM

Quote:

Originally Posted by Bme30

I disagree with both responses. Fuel smell on startup is not normal Catless or not! I'm full catless and have zero fuel smell.
I had very similar issue a while back and it was a leaky injector. How I found out which one I wanted till the next morning after the csr say all night. Started the car and let it idle for 20 seconds. Then pulled each plug till I found the wet one. Yes I had a wet plug! Leaky injector! Replaced and all smell and rough idle was gone.

+1
Leaking injector.

Bmw doubles · 03-14-2015, 06:29 PM

Yup mine was that way until I got all 6 injectors replaced. No more heavy fuel smell on start up, idle or otherwise.

nOshi · 03-14-2015, 08:22 PM

Yup just went through this last week. Def injectors, or the fuel line that connect the injector to the rail not dealing properly.

enrita · 03-15-2015, 12:31 PM

leaky injector, known issue when they start failing. if you get a missfire you know which one it is.

E92Carlos · 03-15-2015, 07:18 PM

Quote:

Originally Posted by LGCubana

From the nature of your question, it sounds like you are brand spanking new to the bolt on. Do you gave either a JB4 or COBB AP ?

If not, you'll be getting error codes for the O2 sensors soon.

Not really "spanking" don't let my post count fool you. I've been FBO for a couple yrs now and meth kit is coming in tommorow. I have also performed turbo swaps and transmission swap on this platform so no im not new to bolt ons.

Like others have mentioned i dont believe stronge fuel smell to be normal at all and a leaky injector would be probable cause just wanted to see if anyone else had experiened this. Apparently pretty common issue. Thank you all !

cjk28 · 08-28-2021, 05:55 AM

Quote:

Originally Posted by Bme30

I disagree with both responses. Fuel smell on startup is not normal Catless or not! I'm full catless and have zero fuel smell.
I had very similar issue a while back and it was a leaky injector. How I found out which one I wanted till the next morning after the csr say all night. Started the car and let it idle for 20 seconds. Then pulled each plug till I found the wet one. Yes I had a wet plug! Leaky injector! Replaced and all smell and rough idle was gone.

sorry to bump an old thread, but can anyone explain why to let it idle for 20 seconds? won't most of the leaked fuel be burned after that long? wont the fuel be sitting on the back of the valves and make its way in after running for 1 second?

edit: assumed this was a thread about port injected engines like my n52. for direct injection surely you dont need to run the engine at all to check the plugs?

iqraceworks · 08-30-2021, 10:00 PM

Yeah.....I don't think you want to run the car before you pull the plugs. The whole point of letting the car sit all night is so that any leaking injectors will drip fuel and let it run down onto the tip of the spark plug. Starting the car before you pull the plugs just burns off those fuel drips.

So no....don't start the car before you pull the plugs.

03-12-2015, 11:11 AM	#1
E92Carlos Banned 17 Rep 99 Posts Drives: Crimson Red E92 Join Date: Nov 2011 Location: Miami iTrader: (1)	Fuel smell on cold starts Hello all , my car is full catless to the stock mufflers when i turn the car on in the morning i get a really strong gas smell from the exhaust and the car sputters for a few seconds and then its super smooth. Can this be a leaking injector ? Or does full catless just smell like that ?
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03-14-2015, 11:16 AM	#4
Bme30 Major 91 Rep 1,039 Posts Drives: 335i coupe Join Date: May 2010 Location: 'Merika' iTrader: (2) Garage List 2007 335i [0.00]	I disagree with both responses. Fuel smell on startup is not normal Catless or not! I'm full catless and have zero fuel smell. I had very similar issue a while back and it was a leaky injector. How I found out which one I wanted till the next morning after the csr say all night. Started the car and let it idle for 20 seconds. Then pulled each plug till I found the wet one. Yes I had a wet plug! Leaky injector! Replaced and all smell and rough idle was gone.
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03-14-2015, 06:29 PM	#6
Bmw doubles Dream crusher 1003 Rep 2,420 Posts Drives: Fast Join Date: Mar 2015 Location: westside iTrader: (0) Garage List 2011 535 [0.00]	Yup mine was that way until I got all 6 injectors replaced. No more heavy fuel smell on start up, idle or otherwise. __________________ 535i MIssion Performance, PS2, Helix HPFP Kit, Wagner FMIC, Spec 3 clutch, Steel SMF, Wolf Racing CP, UUC SSK, GFB dv, SprintBooster, Custom Dynomax Exhaust, M5 Sways, Eibach OE Springs, Koni Sports Adjustable, Custom Short Ram CAI IG: @bmwdoubles
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03-14-2015, 08:22 PM	#7
nOshi Second Lieutenant 23 Rep 251 Posts Drives: TiAg E90 335i Join Date: Apr 2011 Location: Central FL iTrader: (4)	Yup just went through this last week. Def injectors, or the fuel line that connect the injector to the rail not dealing properly.
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03-15-2015, 12:31 PM	#8
enrita Major General 163 Rep 7,377 Posts Drives: 335i - Big turbos Join Date: Sep 2008 Location: Italian in Sweden iTrader: (0)	leaky injector, known issue when they start failing. if you get a missfire you know which one it is. __________________ 07 335i AT - MOTIV 750 - MHD E85 BMS flash - BMS PI - JB4G5 - Okada Coils - NGK 5992 Plugs - Helix IC - Snow Stg. 3 - Stett CP - Custom midpipes with 100 HJS Cats - Bastuck Quad - PSS10 - QUAIFE LSD - BMS OCC - Forge DVs - AR OC - ALCON BBK - M3 Chassi - Dinan CP - Velocity M rear Toe arms - Advan RZ-DF - LUX H8 - Level 10 AT upgrade
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08-30-2021, 10:00 PM	#11
iqraceworks Brigadier General 2114 Rep 3,811 Posts Drives: 2007 335i Join Date: Aug 2019 Location: Missouri iTrader: (0)	Yeah.....I don't think you want to run the car before you pull the plugs. The whole point of letting the car sit all night is so that any leaking injectors will drip fuel and let it run down onto the tip of the spark plug. Starting the car before you pull the plugs just burns off those fuel drips. So no....don't start the car before you pull the plugs.
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