Someone help plz.... before i sell this thing..

[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 ?

[2000CAYukon]

Which plugs did you put in? 02s can affect mileage. Have they ever been replaced?

Has the fuel filter been replaced?

//2000CAYukon

[phat97yukon]

I got iradium plugs in it and when i put those in back in feb/march i noticed a big gas gain and power, ive checked em they still look good, they got mabey 15K on em, the fuel filter was replaced 2 mabey 3 months ago, ive debated the O2 prob, but i figured proboly wouldnt kill the milage that bad, plus i figured it would throw a code....

[rican4lfe]

Originally Posted by 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 ?

I have a 97 Yukon with Airaid intake, Helix Trtle body spacer and gibson headers and ridding it between 1500 and 2000 rpm is giving me 255 miles on the half tank... Hope this helps

[2000CAYukon]

Originally Posted by phat97yukon

I got iradium plugs in it and when i put those in back in feb/march i noticed a big gas gain and power, ive checked em they still look good, they got mabey 15K on em, the fuel filter was replaced 2 mabey 3 months ago, ive debated the O2 prob, but i figured proboly wouldnt kill the milage that bad, plus i figured it would throw a code....

The front 02s tell the PCM air/fuel mixture. The rears check the cat effeciency and help with misfire detection. If the front ones are off, it can affect gas mileage.

Other possibilities are clogged cats, EGR, vacuum leak, incorrect fuel pressure, leaking fuel pressure regulator (how does it start after sitting for 30 minutes??).

Good luck.

//2000CAYukon

[phat97yukon]

Always fires right up no problemo, doenst matter warm or cold, sittin or after a long drive

[sunbeam7011]

How fast is 140 KPH?? How far is 500 Kilometers?? What is this Kilo crap? Talk miles man!!! Thats what I love about my wifes new SSR.......MPH only on the speedo.

[phat97yukon]

Originally Posted by kk7ac

How fast is 140 KPH?? How far is 500 Kilometers?? What is this Kilo crap? Talk miles man!!! Thats what I love about my wifes new SSR.......MPH only on the speedo.

I dont know what 140KPH, is in miles.. I live up here in canada EH, ya know the land of where i gotta keep my truck in 4wd because of the snow all year round, dont wanna make my dogs that tow my sled tired all the time so gotta bust out my truck.... ooh mabey thats where my gas milage is goin, cuz im in 4wd all the time.... JK

[sunbeam7011]

Ae, Canada.... That explains it! - 4WD would certainly hurt the miliage I agree.

[rae61]

Jordan, I have a 98 Yukon and I'm also in Canada, my gas tank
is 113 liters or 25.1 imp gallons thats completely dry. My unit is
stock no up grades, but well maintained, 174000km. I get between
19.5 and 24.5 MPG hiway all depends on conditions and my speed.
I can routinely average 22MPG hiway. City driving is a different question.
I personaly think that 22 MPG is very good for a SUV like this and I'm
happy with my milage. I have owned 17 different trucks and SUVS all 4x4
both gas and diesel and I don't think you can except much better milage
from a full size domestic 4x4 with a big v8.

I did a quick calculation and your 800km per tank works out to
19.7 MPG based on running your tank dry. Do you do an exact calulation
when you fill up, if so what is your MPG and is that city or hiway?

Rick

[phat97yukon]

Originally Posted by rae61

Jordan, I have a 98 Yukon and I'm also in Canada, my gas tank
is 113 liters or 25.1 imp gallons thats completely dry. My unit is
stock no up grades, but well maintained, 174000km. I get between
19.5 and 24.5 MPG hiway all depends on conditions and my speed.
I can routinely average 22MPG hiway. City driving is a different question.
I personaly think that 22 MPG is very good for a SUV like this and I'm
happy with my milage. I have owned 17 different trucks and SUVS all 4x4
both gas and diesel and I don't think you can except much better milage
from a full size domestic 4x4 with a big v8.

I did a quick calculation and your 800km per tank works out to
19.7 MPG based on running your tank dry. Do you do an exact calulation
when you fill up, if so what is your MPG and is that city or hiway?

Rick

Hey Rick, i dont do the exact calculation when i fill up, i either write it down between fills, i dont know how to figure it out to calculate it to get the MPG, or i just always reset the trip odometer .. Im mostly city driving and use to be able to get that beautiful 750 to 800 k to a tank in town and bout 850ish highway, and now highway or in town its 500 to 540 is the farthest i pushed it with the needle burried.. with the gas milage i had when i first got it i was happy, it beat my old 3/4 ton gmc and almost got the same milage outta my old supra, but now it reminds me of a old 60's big block car, hit the gas and watch the gauge drop to empty from a full tank.. if you could get back to me and let me know what to do to calculate my MPG that would be great man...

[rae61]

Jordan, yeh with the cost of gas you sure notice when your MPG drops it sounds like yours is major. It sounds like you motor is burning way to rich.
Do you have any error codes set or pending? Does your motor idle smooth , is there any loss of power between 0-60 mph? pull your plugs and see if any show
signs of missfire or improper combustion.

To figure out MPG I do this. KM x .62 = miles Liters divided by 4.5 = gallons. then divide miles by gallons = MPG. I think any thing in the range of 19-23 MPG (imperial gallon not US) is great.

Rick.

[phat97yukon]

the only code ive ever had was the crank sensor, and that got taken care of when my truck was when in to get the timing done, for some stupid reason my distributer was lose and got turned, ive pulled plugs, they all look clean, no signs on nothin abnormal... as for idle it runs nice and smooth, and 0 to 60MPH i can hit the gas at a light and it will pull hard right up to the point of where i let off...