Engine/Transmission (1998.5 - 2002) Fuel economy went to pot - Any ideas?

[Kyle]

All of the sudden, on my last fillup I calculated 13. 9 mpg. Normally it hovers around 18. 5 with very little variance. My driving habits didn't change nor did the type of trips I took.



The fuel filter is "close" to being due for a change (by the hour meter) but not due yet. My fuel pressure senders are on the blink so I can't tell if there's higher than normal restriction.



The air filter is also "close" to being due for a change, but not due yet. All driving on this air filter has been 99. 9% city. It doesn't look too bad.



I replace 315/75R-16 Big-O mud grips ("D" rated) with Parnelli Jones 35x12. 50R-16 mud grips ("E" rated). Tires are the same size and I would assume that E-rated/stiffer sidewalls would yield a lower rolling resistance.



My questions:

Can any/all of these cause a loss in fuel economy?

What else should I check?



Thanks,

Kyle

 

[mikeberry]

Does the '99 have an A. I. T. ? Sounds like it has been a problem for a few people. Just do a search. lots of info.

 

[DEZLPWR]

Kyle,

You might try cleaning the IAT sensor... . How many total hours & miles are on your truck? I have 3,000hrs and 90,000mi on my '99...

Here's more info on cleaning the IAT:

http://www.dodgeram.org/tech/dsl/sensors/IAT/clean.htm

 

[Kyle]

I had no idea!!!!!

Didn't know such a thing existed (I thought I heard a bell ring, but it was so far off I'm not sure I really heard it). I certainly had forgotten the link with fuel economy and EGT's. Now that I read the link I have noticed that cool-down seems to take longer than before even though ambient temps are dropping (all the way down to a frigid 95 here in Arizona).



I've got 1900 hrs / 52,000 miles. I'll pull and clean the IAT sensor and see what happens. Meanwhile I've got new fuel pressure senders to install but just haven't gotten around to building a remote mounting plate for them. This might just be the motivation I need.



Dezlpwr,

I did a search on "fuel economy" and was pouring through the 15 Billion hits when I noticed your response. Thanks for saving me the time. I had only read about 10,000 of them so I would have been in for a long night.



See there -- I learned something new! This is a great forum.