I installed a new TB because I got the Lightning Bolt dash light. While I was at it I replaced the PCV and MAP sensor. About 2 weeks after the installation my mileage around town dropped from 13.6 to 11.6 mpg. When I drive on the highway I'm only getting 13.6. WIERD! Does anyone have any ideas behind the cause of this? Could it be the TB is faulty?

 

What brand MAP sensor?

 

It was a Delphi MAP Sensor.

 

That should be fine....

Did you reset the PCM after changing everything? (have the battery disconnected while you were working on it?)

 

Yep, I had the battery disconnected! I also did the relearn process on the TB after installation. Is there something else I should have done? By the way Hey You, I had a 99 Ram 2500 Sport with an 8.0 also. I wish I would have kept it and not bought this 07, it was a much better truck with zero problems.

 

That is a SHARP truck. Wish mine looked that good.

How old are your O2 sensors? If you aren't getting any codes...... Got a scanner? Would be interesting to see what fuel trims are.

 

Did you get any codes? TB is 2119.

 

The O2 Sensors are original, so they're 14 years old. I had it on my mechanics scanner and there were no codes, but I'm not sure on the fuel trims. Do you think O2 Sensors would be the cause even if they're not throwing codes? Thanks for the compliment on my old 2500! I kept her in tip-top shape!

 

Nope, it hasn't thrown any codes.

 

O2 sensors age, and become less accurate over time. That, and crap builds up on them, which contributes to inaccuracy.... but, so long as the signal is doing what the PCM thinks it should, they won't set codes. Replacing them isn't a bad idea, at least the front sensors..... it may or may not help though. NTK or Denso sensors only please. These trucks don't like the other guys.