My 87 244 misses when it is started after sitting for a few days. It feels like water in the gas. The problem usually goes away if I add de-icer. This has only been a problem since our gasoline started to have ethanol added. Is it possible that the ethanol is picking up water from the air in the gas tank when it is just sitting? Or could this just be a problem of not high enough octane.
Here is what my supplier's brochure says: "Ethanol is a natural de-icer and attracts water. It will clean up residue, scale and rust from tank walls and bottoms. Ethanol also acts like a mild solvent and will scour gums, varnish and rust particles from your tank surfaces. For these reasons, it is recommended that the tank be drained and flushed as clean as possible before receiving ethanol-blended gasoline. Phase separation may occur when there is too
much water in a fuel tank for the alcohol to absorb and hold in suspension. Under certain conditions, the alcohol and water fall to the bottom of the tank in a layer with the gasoline on top. The gasoline portion may now be out of Canadian General Standards Board specification for octane level as the alcohol was part of the octane component.
I think this is mostly about bulk fuel tanks but could the same thing apply to the car's tank when it sits for a while? Since all of the gas is legislated as 10% ethanol what options are available?

Ethanol has a higher octane than gasoline. It has a lower energy density but that would not factor into this discussion.

10% Ethanol should not be aggressive (corrosive if you are not Politically Correct) enough to attack any non-modern fuel components (natural rubber and less chemical resistant plastics). This should not be a problem with a 240 anyway.

The two things make a flex-fuel car capable of running on Ethanol (E85 and theoretically E100) without major side effects. First, the above mentioned fuel system components. Second is a fuel and ignition computer capable of the wide range of adjustment required to handle a variety of fuels...a wide-band O2 sensor is almost always required.

I typed that last paragraph to say this: something on your car is "marginal" when running on regular fuel and becomes outside of the fuel-injection or ignition maps when running Ethanol. Do a tune up with high quality components to include replace the ignition wires and cleaning the throttle body and idle motor.

Mike

Thanks for this. I changed the plugs and wires and it has been fine since. I waited to reply to make sure everything was still working fine.

I'm embarrassed to admit I thought I had changed the plugs and wires on this car last year but it was my 1800 I changed the wires on.

I appreciate the time and advice you gave me.

Thanks. I will do what you suggest.

I don't think that's an issue with fuel tanks in cars. I've opened enough old Volvo gas tanks and been surprised at how clean they are ( to recycle cars in Canada the tanks must have the bottoms cut out).
Is the misfire random or rhythmic? If the latter, bad spark plug, or a blown head gasket, or a poor injector might be the reason.

Thanks for taking the time to reply to my question. I changed the plugs and wires and it has been running fine.

I'm embarrassed to admit I thought I had new wires in this car but it was my 1800 that got the new plugs and wires.

dave

Thanks. I will check the wires and head gasket.