1997 yukon - bad gas mileage

[westman995]

I have a 1997 yukon. 210k on the body, supposed 150k on motor, supposed rebuilt tranny.. Anyways, after owning this thing for like two years and having constant problems with it. I FINALLY have this thing running good and has the power i think it should..

Now, I feel as if the mileage is HORRIBLE, even for this truck, and i know these trucks dont get good mileage at all, obviously haha..

Right now i keep getting a p0141 code, stating bank 1 sensor 2 has a faulty heater circuit...

Now i have read on the obd2 codes site that it says "may notice poor fuel economy" I would like to know if that can be true? I always thought the two o2 sensors before the cats did all that stuff and the rear ones just "monitored" it kinda..

Im in the process of trying to get that sensor out so i can try another one, but its not in a good spot and its in there pretty good.Hope i dont have to remove the whole exhaust just to get it out.

Is there anything else i should look for?

I was getting a code before, i believe it was p0430 saying, i thought it was my exhaust leak but that leak was on the other bank, even tho after i fixed that leak that code has not came back, however the p0141 keeps coming back..

 

[KPOD]

Assuming your tranny full works, and has overdrive, how many MPG are you getting in the city and highway? Also, what are your RPMs when cruising at 70 on the highway?

 

[westman995]

I honestly have not taken this thing out on the highway since i got it running right.. After i put the fuel pump in i only checked it once and as far as i know, i got like 8-9mpg.. I know these trucks suck on gas, but it has to get a little better than that.

Hopefully that o2 sensor helps some, but im unsure if the rear o2 sensor does anything with mpg

 

[strad]

Rear o2 sensors are to monitor the performance of the cats. They have no other purpose. 11-12 city is what I see with my 99 4wd four door.

 

[westman995]

This is where i read that the mpg could be affected by that.

http://www.obd-codes.com/p0141

12 would be much better than 8, hopefully i can get that fixed.. Ill also try to check mpg again also to be sure.

 

[KPOD]

I just had my engine rebuilt, and with my trans not being able to stay in overdrive (at least I don't think it is, 2k RPMs at 70MPH on the highway) I got 12.5MPG with leaking gas lines and a real dirty CAI this last tank.

 

[_Dylan_]

2000rpm at 70mph would be correct with 3:73 gears.

I would change the sensor and runs a few tanks and see what happens.

 

[Gzes]

Ivwoukd do the fuel filter. Mine was getting like 6mpgs then when i put a new filter it jumped and i have the tbi which is worst at gas then your vortec

 

[SunlitComet]

Rear o2 sensors are to monitor the performance of the cats. They have no other purpose. 11-12 city is what I see with my 99 4wd four door.

they actually play a minor role in fuel trims for the good of the cats.

 

[kaoticlife]

2000rpm at 70mph would be correct with 3:73 gears.

I would change the sensor and runs a few tanks and see what happens.

I run 2100 to 2200 rpm at 80mph and I have 3:73 gears and 20" wheels with 275/55/r20 tires.

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