Hello:

 

I have a 1995 Subaru Legacy Wagon.  EJ22 / 186K.

 

As it has gotten colder car has a fuel smell @ start up.   The fuel smell is coming from the tail pipe and it seems that the car is running rich until it warms up.   It has not thrown any codes.

 

I am thinking that the O2 sensors need to be replaced.   Any thoughts?

 

Thanks much!

Tom

That's just how they were, nice and rich and richer the colder it is. I have a '96 that's like that. Sometime back then Subaru had a bulletin out about it. They said something like they make it run nice and rich to make sure the vehicle will start and run in cold temperatures, something about it being related to the vehicle not being able to know what type of gasoline is in it so they did that to make sure it will run in the cold on gasoline that has a low vapor pressure. (i.e. normally in cold areas the winter blend fuel that starts around October/November has a higher vapor pressure than normal blend).

engine temp sensor may be bad - pretty sure on your car, it is a separate unti from the gauge sender - look for the 2-wire one on the crossover pipe.

 

it may be bad - keeping the car in 'choke' all the time.

+1 on the coolant temp sensor, there is one for the ecu and one for the gauge. The one you want is the two prong for the ecu. when its really cold though they will smell like they are running rich for a bit until the intake can warm up enough to start atomizing the fuel.

 

Check your air filter as well, if it can't breath it will cause this as well

Edited January 14, 201610 yr by mikaleda

Cold engine cold air, needs more fuel in order to run.

 

Gasoline needs to vaporize in order to burn. When its cold its harder for the droplets to vaporize, so a high amount of the gasoline that gets sprayed into the engine doesn't actually burn. It just gets chucked out the tail pipe.

 

O2 sensors don't work until they're about 600°F. During the warmup period the ECU doesn't even look at O2 sensor voltages because they aren't working. It's called open-loop operation. It bases the starting fuel mixure solely on coolant temperature until the O2 sensors get hot enough to start making a signal.

Thanks Texan