help plz gas milage gone down hill...

[phat97yukon]

Hey i gotta 97 yukon, when i first bought it back in dec, i was gettin over 800KM to a tank, with the exaust ive put on and K&N. My buddys dad's 99 tahoe gets 1000KM to a tank stock... In the last lil while , ive done a bunch of stuff to my truck tune up wise cuz ive noticed the gas milage has gone down hill big time put in a , installed msd wires, new cap , rotor, had it sent in to the dealer to get the timing done, cleaned my throttle body and MAF, but i clean those every oil change, fuel filter.... Now im wondering what the heck would kill my gas milage, im now lucky to get 500Km to a tank at 90 bucks to fill im not impressed with, also ive noticed goin down the highway, hit about 140KPH, when i step on it, it kinda sounds like its choking its self out with a weird sputter, VS before i could pin it at 120KPH and it would pull right till it hits the rev limiter...

 

If anyone has any idea's here wtf is goin on or to give me some other stuff to check out please let me know, if i cant get this crappy gas milage fixed, im goin to be sellin my yukon.... Also how many KM/miles to a tank are you tahoe/yukon guys gettin ?

[MrQuadrasteer]

O2s ??

[phat97yukon]

O2s ??

 

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No codes have come up fer it, and i didnt think it would kill the milage that bad..

[MrQuadrasteer]

Dude, my O2s went out on my Cherokee.... I went from 16mpg to like 4mpg. No exaggeration....

 

O2s will RUIN you....

 

Well, at least on a 4.0 Jeep.....

[phat97yukon]

Wholy crap man thats insane... hummm i hope not thats a few bucks in O2's, is there any good way of testing them..

[MrQuadrasteer]

I was leaving a trail of smoke you could hardly see thru. Cars were honking, nobody would get w/in a half-mile behind me !!!!

 

2-O2s, $100+ for one, like $85 for the other.

 

There's a test procedure for them, but I think it sucks. I tested the originals and they failed. Tested the new ones... they failed too

[phat97yukon]

hey also ive noticed i was a dumb ass and put this in the wrong section.. if someone could move it to fullsize SUV's that would be great...

[Tex2kZR2]

Umm. Yukon is Fullsize right.. Get you big booty outta here. Besides you can probably find more help if you post in the correct forum. ;)