335i cold start and fuel

pmmcbl · 09-13-2015, 11:30 AM

Hello all.

There are plenty on notes on forums about white smoke or blue from cold starts on 335i models.

I couldn't find what my car is currently suffering.
Only on cold starts I get the following and wanted to know if you guys get it or not.

Start the car first time.
Ok for around 3 seconds
Then I get what appears to be condensation for around 3 seconds, I can smell fuel.
After that not smoke or smell for a while.
Then after maybe 1 minute I get normal condensation

Is this normal? Thank you

Aragorn30d · 09-13-2015, 12:17 PM

Sounds fine tbh. Engines run rich when they're first started, and it takes a bit of time for the cats to come up to temperature to be able to catalyse the excess fuel, so you'll get some fuel smell immediately after starting.

Condensation/Steam/"white smoke" is just water from the inside of the exhaust heating up and coming out as steam. It happens because as the exhuast cools, moisture condenses inside the exhaust system. The engine itself also produces water in the exhaust gas, which can condense on the cold pipework, before evaporating again once it heats up.

Blue smoke on startup could indicate a potential issue, but its more common than you'd think, especially on decatted turbocharged engines. Usually you wont even notice it unless your looking for it.

Unless it was reeking out blue smoke when driving or idling when warm i wouldnt be all that worried.

pmmcbl · 09-13-2015, 01:00 PM

Thank you.
Not worried to be honest, just steam but didn't expect it to have it during a start up. Steam normally kicks in after a minute or two.

AWSAWS · 09-14-2015, 04:11 AM

Quote:

Originally Posted by pmmcbl

Thank you.
Not worried to be honest, just steam but didn't expect it to have it during a start up. Steam normally kicks in after a minute or two.

I imagine exhaust gas which is full of steam gets trapped in the exhaust system as soon as the engine goes off and condenses. Then when the engine and exhaust heats, (next time the car is started) it forms steam again.

Dann · 09-14-2015, 07:48 AM

My E36 used to steam like crazy when the ambient temps were colder (like would make a proper smoke cloud)
The 335i has started steaming a little bit now and will probably get worse as temps drop.

Just condensation and nothing to worry about unless it's thick and White or Blue.

pmmcbl · 09-14-2015, 04:17 PM

Thank you guys, feedback very welcomed. Yes, the temp has been low in the morning and this is when I noticed.

I had a closer look today and does look condensation to me together with Fuel smell. The steam is clear until it reaches the end of the pipe and turns into steam. Just odd when it goes away for a minute before your normal code station kicks in.
Never seen that on any other car. Glad I'm not the only one.
Thank you

09-13-2015, 11:30 AM	#1
pmmcbl Lieutenant 35 Rep 435 Posts Drives: E91 335i M-Sport Join Date: Aug 2015 Location: Berkshire iTrader: (0)	335i cold start and fuel Hello all. There are plenty on notes on forums about white smoke or blue from cold starts on 335i models. I couldn't find what my car is currently suffering. Only on cold starts I get the following and wanted to know if you guys get it or not. Start the car first time. Ok for around 3 seconds Then I get what appears to be condensation for around 3 seconds, I can smell fuel. After that not smoke or smell for a while. Then after maybe 1 minute I get normal condensation Is this normal? Thank you
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09-13-2015, 12:17 PM	#2
Aragorn30d Lieutenant Colonel 175 Rep 1,596 Posts Drives: E90 330d Join Date: Mar 2015 Location: Fife iTrader: (0)	Sounds fine tbh. Engines run rich when they're first started, and it takes a bit of time for the cats to come up to temperature to be able to catalyse the excess fuel, so you'll get some fuel smell immediately after starting. Condensation/Steam/"white smoke" is just water from the inside of the exhaust heating up and coming out as steam. It happens because as the exhuast cools, moisture condenses inside the exhaust system. The engine itself also produces water in the exhaust gas, which can condense on the cold pipework, before evaporating again once it heats up. Blue smoke on startup could indicate a potential issue, but its more common than you'd think, especially on decatted turbocharged engines. Usually you wont even notice it unless your looking for it. Unless it was reeking out blue smoke when driving or idling when warm i wouldnt be all that worried.
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09-13-2015, 01:00 PM	#3
pmmcbl Lieutenant 35 Rep 435 Posts Drives: E91 335i M-Sport Join Date: Aug 2015 Location: Berkshire iTrader: (0)	Thank you. Not worried to be honest, just steam but didn't expect it to have it during a start up. Steam normally kicks in after a minute or two.
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09-14-2015, 07:48 AM	#5
Dann Major 133 Rep 1,381 Posts Drives: E90 LCi 335i Join Date: Feb 2015 Location: Portsmouth, United Kingdom iTrader: (0)	My E36 used to steam like crazy when the ambient temps were colder (like would make a proper smoke cloud) The 335i has started steaming a little bit now and will probably get worse as temps drop. Just condensation and nothing to worry about unless it's thick and White or Blue. __________________ My Individual E90 LCI 335i
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09-14-2015, 04:17 PM	#6
pmmcbl Lieutenant 35 Rep 435 Posts Drives: E91 335i M-Sport Join Date: Aug 2015 Location: Berkshire iTrader: (0)	Thank you guys, feedback very welcomed. Yes, the temp has been low in the morning and this is when I noticed. I had a closer look today and does look condensation to me together with Fuel smell. The steam is clear until it reaches the end of the pipe and turns into steam. Just odd when it goes away for a minute before your normal code station kicks in. Never seen that on any other car. Glad I'm not the only one. Thank you
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