Engine/Transmission (1998.5 - 2002) MPG Problem

[pangelechio]

Last fall i was getting 18-19 mpg. around november it slipped to 15 and i assumed it was winter fuel. here it is june and milage still sucks. no mods other than K&N on my 2000 auto and only 65K miles on it. power feels ok but any ideas on where the 4 mpg went? a few weeks ago i pulled my trailer to the mountains and ran into an interest problem that may be related. on long pulls the truck just couldn't get with the program to the point that the engine wouldn't pick up more rpms (stopped at 2300 or so) and wouldn't kick down from lockup. the guy's at NWB had some suggestions but nothing working so far.

 

[johncameron]

Check your codes by turning on and off your key three times. Prey that P0216 does NOT show! Inj pump??

JC

 

[PKozlowski]

Check your lift pump pressure and volume I'll bet it's low.

 

[Silver Bullet Ram]

For your sake, I hope its not your injector pump. You hate you fuel mileage now, you will really hate then. Most who have changed their injection pumps out including myself are reporting about 11 mpg. Check your map sensor, sometimes that is the culprit.



Gary

 

[MDale]

Since you have a K&N filter, I would try cleaning the IAT sensor and Cleaning/check the MAP sensor. When I had a k&n the IAT got pretty dirty. I picked up 2. 5mpg from cleaning the sensor. Good-luck

 

[DLove]

I had the same problem, it turned out to be the map sensor. I changed it and there was an instant 4 mpg increase. There were no codes since the sensor was mechanically gummed up but electronically fine.



-Dan

 

[pangelechio]

Thanks for all the info, I will check it all out today! I hope it is only a MAP issue, 0216 could mean a little trouble.



Philip

 

[pangelechio]

Check your codes by turning on and off your key three times. Prey that P0216 does NOT show! Inj pump??

JC

Well, the only code that came up was "p done" so I hope thats a good thing. Where is the MAP sensor on this truck? ( I don't have a repair manual yet)

 

[johncameron]

Well, the only code that came up was "p done" so I hope thats a good thing. )

Pdone means

 

[pangelechio]

MPG? Still no answer

So, fuel is at 15# and MAP checks good even on the scanner. Not sure what else to check, air filter looks good too. MDale mentioned the IAT sensor..... ok I give, what is it and where do I locate it?



Thanks again for the suggestions.

 

[nps]

So, fuel is at 15# and MAP checks good even on the scanner. Not sure what else to check, air filter looks good too. MDale mentioned the IAT sensor..... ok I give, what is it and where do I locate it?



Thanks again for the suggestions.

Back of the head - higher than the MAP and farther back. Click here for Dodge Ram information - they have a picture showing the location and specs on the resistance values.



I had excessive smoke - my IAT resistance values were +/- good. I even bypassed the IAT with an adjustable pot so I could dial-a-temp in cab. Conclusion - it needs to be right - not too high or too low. So I changed the IAT and everything is good. Bottom line - try cleaning it but even if it tests close just change it.



Funny thing about this part is that the dealer is cheaper than Cummins. But I got mine from Cummins because the dealer didn't stock it and I didn't want to make 2 trips (one to order/pay and another to pickup). So I paid Cummins $5 more. The first one they brought out was already installed (tech trying parts from the parts room).