Engine/Transmission (1998.5 - 2002) Bad Mileage 01'

[Stixx]

My Mom drives a 01 5 spd with 82k on it. I changed the fuel filter on it the other day and ever since then the mileage on the truck has dropped BAD. like 8-10 mpg.



Has anyone heard of this?

There is no outside leaks.

I'm new to the 24v's but I noticed the prime loc or whatever that lil thing on the filter is stuck open when I changed the filter. I moved it around and got it closed again.



any ideas would help

 

[Alan Reagan]

That's the bleed valve to get water out of the filter cannister. Sometimes they will hang up and you'll pump fuel on the ground if you don't catch the little mistake. Check and make sure fuel isn't still leaking out of the little drain hose.



Changing the filter won't make your mileage drop like that. There has to be something you are missing. Is it hard to start, down on power since the change?

 

[Stixx]

Starts good and runs good.

I just checked to see if that drain hose was leaking while it was running and it wasnt.



I'm not saying for sure that when I changed the filter it caused the mileage to drop.



I cant see how a filter change would do it, but like I said I'm new to the 24v motors so I wasnt sure.

Is there a senor or something that could have gone bad?

 

[Alan Reagan]

The IAT sensor could probably use a cleaning



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



Make sure all turbo hose clamps are nice and snug.

Check from the turbo down to the intercooler and up to the intake.



If you own a torque wrench, take a 10mm socket and the torque wrench (you'll need a six inch extension) and tighten the intake cover bolts to 18 ft lbs. #25 in the following link is the cover:



http://www.dodgeram.org/tech/dsl/mt_2_feb98/fuel_sys_comp.htm



Make sure you get the bolts through the intake plenum.



One other thing that will be hurting you right now is if you are running winter blend fuel. That will take about 2 mpg from you.



Sounds like some general maintenance may take care of your problem.

 

[Behr]

Alan...



is there no code or engine light to advise the IAT is faulty or dirty. . ??



Also... . is there a sensor that monitors air pressure within the intake ??



Just two questions this time around... ...

 

[Behr]

Hi Stixx



I came across this link... . you might find helpful regarding your IAT... and your fuel mileage.....



http://www.smokindiesel.com/Technical.htm



Hope this helps a little... .

 

[Alan Reagan]

Originally posted by Behr

Alan...



is there no code or engine light to advise the IAT is faulty or dirty. . ??



Also... . is there a sensor that monitors air pressure within the intake ??



Just two questions this time around... ...

There is not a code or engine light to let you know it's dirty. The only code is if there is an over/under voltage on the sensor. The cause of the voltage problem is if the sensor completely shorts out (undervoltage) or if it opens (overvoltage). Usually the only time you see a fault with the IAT (check engine light and code) is if you have it disconnected and turn the key to "on". Guess how I know .



There is a sensor that monitors air pressure. It's the MAP sensor located near the rear of the intake manifold, drivers side. It has the same faults as the IAT sensor. Either can cause mileage problems if they are not working properly but to set a code requires both sensors to have the over/undervoltage fault.

 

[Behr]

Thanks Alan.....



I was just reading up on the link I posted in this thread just prior to your reply.



My concern right now is (change of topic) but is lubrication for the injector pump. Does part of the pump get its lubrication from the engine oil (crankcase) or is lubrication strickly from the fuel??



I use Stanadyne Lubricity and their performance. But now I am seeing where some people add 2 cycle motor oil to thier fuel for lubrication.



I know I am off topic here... .

 

[RKohn]

Hmmm.... pondering your comments and the 15watt bulb started to glow.

How about opening the little valve back up and draining out everything in the housing, then refilling it with fresh #2 (a little of your favorite additive wouldn't hurt) and put in a new filter.



Go Mom Go!!! Oo. Oo. Oo.

 

[Stixx]

Thanks for the links.



I'll mess around with that sensor and see what I can gather.

 

[kboettcher]

Is there an easy way to check the MAP sensor, like you can with the IAT sensor and a multi-meter?

 

[JCyrbok]

INtake bolts

I too have had decreasing mileage and merely chalked it up to the cold winter months. After I saw this thread and checked my INTAKE COVER BOLTS I found that not a single one was torqued to spec. One of the lower ones was about 17 lbs/ft but the rest were way offm with each needing about at least 3/4 to a full turn to get them to 18 lbs/ft. We'll see how that does.



Also anyone have any tips for removeal/install of the IAT. I could not get to it from above, no matter how hard I tried. Too many bundles of wires and a large bracket for the throttle cable in the way. Does it have to be gotten from underneath?



Kinda looks like there is a clear shot from below but dont know if my arms will reach.



Thanks

J-

 

[Alan Reagan]

Make sure you are looking at the IAT and not the MAP sensor.



http://www.dodgeram.org/tech/dsl/mt_2_feb98/fuel_sys_comp.htm



I don't remember a throttle bracket back there that far.



The easiest way I've found to get to the thing is with my knees on the radiator. Left hand on the valve cover. Just lean forward, use a 6 inch extension and remove the sensor with your right hand.

 

[JCyrbok]

NO thats it

Yeah I know, I triple checked it on TDR, Dodge ram .org and service manuel and all show its the one WAYYYYYYYY back there. MAP is just above and to right of fuel filter.



I'll try the climb on the engine trick. My luck i'll get stuck some how though. SOmeone put 911 in the cell phone just dont push send yet. LOL.



Thanks

J-