Engine/Transmission (1998.5 - 2002) mpg

[Moe]

It's been a while since I posted anything, but here goes. I've got a 99 3500 that gets really lousy mileage with the CTD. I can smell fresh fuel on occasion up front but havent been able to find any leaks. What gives?

 

[trqmnstr]

What kind of mpg is really lousy?

 

[Moe]

It was getting 19 mpg when I bought it 4 months ago, however its down to 13. 9 now. It still has plenty of power. I have some kind of leak but cant find it around the rear of the engine.

 

[CrazieAbe]

sounds like the winter diesel could be doing it? what is your location? my 99 gets 16 in the summer, thirteen to fourteen in the winter...

 

[CrazieAbe]

duh, I just noticed your location, does Coshocton,Oh have arctic diesel?

 

[amillstream]

I've got a 01 and have noticed mine is down to 11-13 instead of the normal 15-17mpg. I'm blaming it on the winter fuel but not sure. My brothers fuel milage really dropped when he ran it out of fuel once. (he has a 97 12 valve) He thinks it damaged something but I didn't think you could hurt those injection pumps by running them out of fuel.



I thought I read a thread a long while back about a sensor that needs cleaned once in a while that could effect mileage on these 24 valves. Does anyone know anything about that? My FASS fuel presure is all over the place too, I think that spring that everyone talks about is sticking or something, but I don't think that would affect mileage.

 

[SnoKing]

That would be the IAT sensor, near the rear of the head on the drives side. Kind a PITA to get at to remove. Takes a fairly larger scocket to remove. Do a search on cleaning IAT. SNOKING

 

[Graphic man]

check your map sensor

i have heard a lot of people with bad MPG and power loss and as soon as they change there map it fixed there problem and plus the got there power back and none of them were getting codes of a bad map

 

[rkressg]

Clean your IAT (intake air temp) sensor. Also, If you have a K&N air filter, your MAP is shot and will need replaced. Also, depending upon the mileage, a valve lash adjustment might help. Finally, you should see some improvement when the weather warms up. Winter fuel will cost around 2mpg.



-Rich

 

[Moe]

Thanks guys, I will give it a try when the weather breaks. This is my 3rd CTD and the worst one for mileage.