I have a 97 LS nothing crazy just intake an exhaust. I was getting around 35-40mpg highway city never paid too much attention to. anyways

Its been pretty cold here lately under 35 degrees on cold night and this is just the start. and now my car is getting the worst mileage ive ever seen and I had a 93 LS this time last year and its mileage was not this bad. I still got good power if not better from the cold air. But It took me over a half tank for 85miles. and I put in another quarter tank drove not even 30 miles and I am nearly empty again. What can this be causing this?

I got NGK G power platnium plugs just replaced in augest. NGK wires good, and a fairly new cap and rotor. Running 10w30 mobil 1. None of this happened until it got cold, could it be my IAT sensor thanks.

 

Check to see if you have any fuel line or tank leaks.

Ali

 

none that I can see and I don't smell any fuel. I reset my ecu today and put my tires on 35 on the dot from 31psi hopefully someone comes good.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by speedracer209 &raquo;</TD></TR><TR><TD CLASS="quote">none that I can see and I don't smell any fuel. I reset my ecu today and put my tires on 35 on the dot from 31psi hopefully someone comes good.</TD></TR></TABLE>

35/33 F/R is a good starting point for tire PSI

 

is your car warming up properley? I just read in my Chilton yesterday that a cold engine uses twice as much fuel as a warm one.

 

try replacing your fuel filter and do a tune-up.

 

any chance your o2 sensor went bad? When mine went out I could only get ~180 miles to the tank!

 

Only gaseous hydrocarbons burn, consequently if the air is cold, then the fuel has to be very volatile. But when summer comes, a volatile fuel can boil and cause vapour lock, as well as producing high levels of evaporative emissions. The solution was to adjust the volatility of the fuel according to altitude and ambient temperature. This volatility change has been automatically performed for decades by the oil companies without informing the public of the changes. It is one reason why storage of gasoline through seasons is not a good idea. Gasoline volatility is being reduced as modern engines, with their fuel injection and management systems, can automatically compensate for some of the changes in ambient conditions - such as altitude and air temperature, resulting in acceptable driveability using less volatile fuel,the STOICH(air/fuel mix) is different for every different season this could be why your car get crappy milage in the winter, taken from http://blizzard.rwic.und.edu/~....html

 

My car does take a long time to warm up. Its about a quarter way when I am fuly warmed up on a cold night. Sometimes even lower on the highway.

 

I would check the O2 sensor also or if your car has a MAF than if its going out the car will get crappy mileage but it will run rough, and if a sensor is out the CEL comes on so... I had a dpfe sensor go out on a ford i owned and it effected the fuel milage also. Just some idea's.

 

It's a combination of things from the cold weather.

The oxygen sensor closed-loop feedback has to compensate more, tire pressures are lower, and the engine is going to take longer to warm up and switch to closed loop as well as for the ECT and IAT correction factors to come down from cold enrichment.

If the needle is only 1/4 of the way up the cluster gauge, then the ECT sensor is probably only seeing around 150 deg F. Coolant temps have to surpass 175 deg F to reach full operating temperature so that the ECT cold enrichment correction factor is minimal and so that the oxygen sensor closed-loop feedback turns on.

 

Resetting the ECU should help a good deal. If that doesn't help any ... check the O2 sensor and get some fuel injector cleaner.