Engine/Transmission (1998.5 - 2002) poor mpg

[MSalvatore]

Hi all,

I have been at 15. 4-15. 9 mpg for a few months now cant seem to get more. Ihave checked for leaks ,none FP is steady at 14 cruising 9 or 10 wot iat is clean air filter is clean someone mentioned map sensor. It is next to iat correct how can I check it ? are there ohm specs? with the price of diesel this sucks . injector pump is new and so is LP my comp is untapped before it was and I was at 19 or so could not having wire tapped cause a mileage drop?



TIA,

Marc

 

[johncameron]

what speed are you traveling at?

 

[MSalvatore]

cruising at 65-70 same as before



Marc

 

[DKupfrian]

I see its a 2002, have you owned it since new? Every winter mine drops from 19. 5 mpg to 15. 5 mpg. I have attributed this to two things:



1) Cold weather = thicker oil



2) Winter blend fuel. I swear I can tell in the fall and spring the minute they change. My milage changes instantly. Am I crazy??

 

[JeffWhite]

Nope. Me too. It helps mine a little to keep grille blocked off below 40-50 degrees,

I'm talking unloaded here. But it still loses a little.

 

[johncameron]

I see its a 2002, have you owned it since new? Every winter mine drops from 19. 5 mpg to 15. 5 mpg. I have attributed this to two things:



1) Cold weather = thicker oil



2) Winter blend fuel. I swear I can tell in the fall and spring the minute they change. My milage changes instantly. Am I crazy??

No your not crazy! The same thing happens to me. I try not to idle for more than a couple minutes even when cold. I start her up, let the oil move around for +- 1 min then drive easy until the temps come up. As we all know, ideling for 15 minutes just wastes fuel, they don't seem to warm up at all.



JC

 

[ntillm01]

Nope, not crazy. Lots of things in the winter add up to lesser fuel mileage. In my case, it's only a ten mile commute to work. Even if I've got the block heater plugged in the engine is only just hitting operating temp when I get there.



Someone will correct me if I'm way off base but... the diesel engine depends on hot air to ignite the fuel. So, colder air in=colder compression temp=less efficient burn=more fuel needed to make the same amount of power. Do you notice how much more effortless it is to make power when the warm temps come?



Of course there's the oil thing. Thicker oil is more drag. But then so is the winter slush or the extra wind I have to push through. So is the extra drag on the alternator to run the heated seats, heated mirrors, wipers, headlights, grid heaters, high blower for heat... or maybe the snow I'm driving around with in the bed that I haven't cleared out yet.



I don't notice the fuel change, neccessarily. I just know fuel economy drops in the winter.