In this cold snap we are having all of a sudden, my gas milage went from 230ish km on half a tank to 150km on a half a tank. Also, the truck sounds and feels rich. Almost like a pre detenation or something. I was about to check and clean the MAF. What else could be causing this drastic decrease in milage? Bad fuel?

Thanks

 

Cold air is like compressed air.. takes more fuel to acheive the proper air/fuel ratio, so a decrease is normal...

But other things to look at are.. do they swith to "oxygenated" fuel in the winter there? A temp senor could be going out, and with the cold snap the engine isnt quite as warm so the ECU, with bad sensor info, is dumping in more fuel to get it up to operating temp.

 

where are these temp sensors?

 

dont know on a 3.4.... IIRC a 22RE has many of them, so a 3.4 may be the same....

Another thought.. how cold is it? The gas your pumping is coming out of the ground at a much warmer temp, by the time it cools its a smaller volume.... that with the typical worse mileage in cold temps could be enough.. I would wait until the next fiilup and you get a # before replacing parts... And if your tire pressure was set in warm temps, there a lot lower now, takes more gas to move em...

 

Its hoverying around -5 celcius right now. There must be something. The truck had exceptional fuel milage last winter. Last winter I didnt have the trueflow air filter, MIT, or deckplate mod yet. Would that make a big difference?

 

Not sure what the MIT is, and -5 isnt that cold.. we only lost 2mpg when it was 10F outside for a month...

Yeah, I agree something sounds a little off....

 

Anyone?

 

Don't forget that your tire pressure will drop approximately 1 psi for every 10 degree F drop in temperature. So if you put, say, 30 psi in at 80 deg. F ambient and now it's 20 deg. F, you've lost about 6 psi in your tires. I know it kills my mileage on my Firestones...

 

Greg,

I noticed a drop in economy as well on my '99. Not as drastic as yours thought. At next fill-up I will cap my deckplate to see of that makes a difference.

Are you driving more aggressively in order to bring engine temp up faster? Check the economy on the second half tank - is it the same as before (only valid if you're driving long distance)?

uberhahn

 

this last tank has been 100% in the city, and i don't think we will belaving for a while. This weekend I am going to clean my MAF, and maybe my air filter if it needs it. If that doesnt work I will be capping my deckplate and maybe visiting the dealer. Keep me posted on what you find.

 

So I finally cleaned my MAF. I saw 2 little sensors inside that looked like they measure air flow. The big one on the outside looked like it measured either temperature or moisture. The big one was just black, so after cleaning all the sensors, I am hoping to see an improvement. I will post again when this tank is finished.

 

Hope this helps out!