Poor gas mileage question

[floridayukon]

My 2001 Yukon XL has been running great until recently I noticed getting only 9-10 mpg's. When I took it out on the highway I notice a bit of hestitation at cruising speeds and when I floor it the "service engine soon" blinks until I let off. I get no cel lights and all service is up to date. I do have 203k but it still runs great around town.

 

[Wake]

Maybe bad gas?

If the CEL is blinking while the engine is under load it's having a problem with the ignition cycle. It could be bad gas, worn plugs, bad wires, maybe even an O2 sensor that might need to be replaced with high mileage.

Also cat converters when they go bad they keep the engine from breathing under load and would also fit the behavior your experiencing. If the engine runs fine under low loads like city driving but feels sluggish at highway speeds and under load it's a good indication of a plugged cat.

 

[ATL]

agreed, id start with the simple tune up stuff first and report back

 

[floridayukon]

Thanks, will do.

 

[ATL]

also, it may be worth it to buy a scanner. i got mine for $30 off amazon and it sure helps when the reduced engine power issue occurs. itll pay for its self first time it points a problem out for u

 

[DenaliAK]

It doesn't sound like this is the problem, but when my fuel pump was dying my mileage dropped. Got a new one and gained back a couple mpg's....

 

[waxworkz]

clean your throttle body!

 

[felixgun]

I had an 01 Z71 Tahoe that got 10mpg and I kept it in 2wd for the most part... sounds like the mileage isn't too far from the norm.

 

[zrxoa1]

Wow! 10 mpg???? My '01 Yukon xl got 18-20mpg. I am crying now with an '07 that gets 12mpg...




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[bikerglasses]

I get about 12.5 on mine with 35's and 4.56's, not too bad considering.

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[01Konvict]

I get about 13.5-14.5mpg with 33s between city/small highway driving

 

[ATL]

i just made a 600 mile trip, i reset all my readings and averaged 13.8 mpg. and it was 90% hwy

---------- Post added at 10:01 AM ---------- Previous post was at 09:57 AM ----------

Wow! 10 mpg???? My '01 Yukon xl got 18-20mpg.

come on man, you dont gotta lie to kick it

 

[Gzes]

I get about 12 stock on suspension and engine.... can't wait til the loft and mud tires lol

 

[TheYuk]

I'm getting 14.5-15.5 in the city(I coast a lot), and the last time I was on the highway I got 17.5.

 

[Gzes]

On my last highway trip I got one full tank for alittle bit over 600 miles so.... I don't feel like calculating