Gas mileage cut in half.

Novawill72 · Aug 13, 2019

Hey all, recently replaced both cats in my 96 Ram 2500, it has the 5.7L Hemi with about 111k on it. 3 days after the codes came back saying 2 bank was reading incorrectly. Cleared the codes, and came back in about 2 days. Added nonfouler to the rear o2 sensor. The code is gone but my gas mileage went from 11 mpg down to like 6 mpg. I am at a loss as to what is going on? I got a new o2 sensor and am about to remove the nonfouler and replace the sensor. Am I going in the right direction? Thoughts, ideas, suggestions? This is my first Ram.

Thanks in advance.
Will

joshuaedmister · Aug 13, 2019

Novawill72 said:
Hey all, recently replaced both cats in my 96 Ram 2500, it has the 5.7L Hemi with about 111k on it. 3 days after the codes came back saying 2 bank was reading incorrectly. Cleared the codes, and came back in about 2 days. Added nonfouler to the rear o2 sensor. The code is gone but my gas mileage went from 11 mpg down to like 6 mpg. I am at a loss as to what is going on? I got a new o2 sensor and am about to remove the nonfouler and replace the sensor. Am I going in the right direction? Thoughts, ideas, suggestions? This is my first Ram.

Thanks in advance.
Will

I would say the right direction, when you're fuel mileage drops like that it's most likely an o2 sensor, especially if it's throwing a code, it'll play with your fuel/air ratio and throw it all out of wack and it just kinda throws everything in instead of making optimum power for fuel because it doesn't know what it's getting out of it

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Novawill72 · Aug 13, 2019

Good to know. Thank you. I am literslly under the truck right now.

joshuaedmister · Aug 13, 2019

Yeah no problem, and if that doesn't fix it check wiring or the plugs where they connect to your harness, I've heard of loose connections or stretched wires too sometimes

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Novawill72 · Aug 13, 2019

Good news do far, temoved the nonfouler, replaced the o2 sensor and went to get gas. When ibpulled out of the driveway was reading 7 mpg, four miles later when I got home was up to 7.5 mpg and no CEL. Hope it keeps climbing as I drive it more.

HemiLonestar · Aug 13, 2019

Novawill72 said:
Hey all, recently replaced both cats in my 96 Ram 2500, it has the 5.7L Hemi with about 111k on it.

You have a 96 with a hemi in it?

Novawill72 · Aug 13, 2019

Sorry, fat fingers should have been 06.

HemiLonestar · Aug 13, 2019

Novawill72 said:
Sorry, fat fingers should have been 06.

Ahh...I was about to be suitably impressed lol

Marley · Aug 13, 2019

I'm a little confused.....non-foulers are placed downstream and upstream 02's measure air fuel mixture.
I did the same thing with great results.

Novawill72 · Aug 13, 2019

Well the info I had said place just downstream. Doesn't matter now, I removed it and replaced the o2 downstream o2 sensor. So far no CEL, need to make mire than a 5 mile run though to see what the mpg does.

Novawill72 · Aug 16, 2019

Novawill72 said:
Hey all, recently replaced both cats in my 96 Ram 2500, it has the 5.7L Hemi with about 111k on it. 3 days after the codes came back saying 2 bank was reading incorrectly. Cleared the codes, and came back in about 2 days. Added nonfouler to the rear o2 sensor. The code is gone but my gas mileage went from 11 mpg down to like 6 mpg. I am at a loss as to what is going on? I got a new o2 sensor and am about to remove the nonfouler and replace the sensor. Am I going in the right direction? Thoughts, ideas, suggestions? This is my first Ram.

Thanks in advance.
Will

Update: Well, I got out and drove about 30 miles round trip. MPG made its way up to 9.7. I think it's fixed. Thank you everyone.

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LoneWolf3574 · Aug 18, 2019

Keep us posted

joshuaedmister · Aug 27, 2019

LoneWolf3574 said:
Keep us posted

If I had to guess it worked for them lol, otherwise they'd be back already, if you're having the same issue usually if you're mpg drops out of nowhere (but they usually throw a code earlier) then its most likely an o2 sensor

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Novawill72 · Aug 27, 2019

Check engine light came back on today saying the same sensor is bad. I know its not the cat as that was replaced about a month ago. I do think I have been hearing a slight exhaust leak went under this morning and sure enough the one side if the collector was loose. Also have 2 snapped off exhaust manifold bolts. Looks like they are flush to the manifold so hopefully a muffler shop can get them out. But for now its just going to have to be as I am going elk hunting starting Friday.

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LoneWolf3574 · Aug 28, 2019

Novawill72 said:
Check engine light came back on today saying the same sensor is bad. I know its not the cat as that was replaced about a month ago. I do think I have been hearing a slight exhaust leak went under this morning and sure enough the one side if the collector was loose. Also have 2 snapped off exhaust manifold bolts. Looks like they are flush to the manifold so hopefully a muffler shop can get them out. But for now its just going to have to be as I am going elk hunting starting Friday.

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Bummer

Marley · Aug 28, 2019

Elk hunting vs engine codes ?
I'll take Elk hunting all day.

Novawill72 · Sep 29, 2019

Hey, all just thought I would give and update. I traded in the 06 2500 for a 2018 2500 Cummins today. Cant wait to take it out. I will post some pics tomorrow.

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Gas mileage cut in half.

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