04 Yukon Xl Running Like Chit... Please Advise!

[macds]

Its been pretty cold here lately (-23 c) in the mornings, and i have noticed that my fuel mileage has been terrible.

When i leave the house with the engine cold, im getting about 25 l/100km cruising at 90km/h.

When the temp guage get up to running temp, im down to about 13.5-15 l/100 km, which still seems high to me.

Tonight on my way home my SES light came on, and i immediately noticed that my DIC was showing 11l/100 km, which seems more appropriate.

Checked the code and got a p0151 which is o2 pre cat right bank, i think? (drivers side).

 

Anyways, its cold out and i want to spend as little time outside, so should i start with cleaning the MAF?

Ive read about the intake gasket issues! damn it

 

Vehicle is a bone stock 04 XL with 98000 kms...

 

Sorry for the metric talk..... but thats all i know

Checked the MAF, and it was spotless....

 

Now im getting p0151, p0174, and p0300 and the truck is running really rough at idle here and there, but not all the time. Its also REALLY snortin gas, like 30l/100.

So now with the misfire in there im really stumped.

The exhaust stanks, and im wondering if a plugged cat could cause one side to go lean?

Are there 2 cats on these trucks? I just got it 2 weeks ago, and having crawled under yet! was hoping for warmer weather!

 

Anyways, I just got back from a little drive, and i now have some more info

Noticed that the tail pipe is sputtering black crap, and lots of moisture

When i got out of the truck, it smelled really bad, like the rotten eggs/fireworks smell, but not from the tailpipe itself, just from underneath the truck?

 

Also have some freeze frame data from the scan tool;

 

P0300 Freeze frame data

 

Fuel System 1 - Open loop

Fuel System 2 - open loop

Calculated load - 3.5 %

Coolant temp - 107F

STFT bank 1 - 3.1 %

LTFT bank 1 - 3.1 %

STFT bank 2 - 50.7 %

LTFT bank 2 - 25.0 %

Intake manifold pressure - 11.8 in.hg

Engine rpm - 638 rpm

Vehicle Speed - 0 mph

Mass air flow sensor - 001.18 lb/min

TPS - 12.5 %

 

Does this info help out at all?

 

Thanks

 

 

Stu

[pwall]

Sounds like how my truck as running a year ago or so. Turned out to be a bad o2 sensor.

 

And welcome to

 

Where you from?

[Bostonsfavson]

Definitely sounds like a clogged cat to me. Welcom to the site, and good luck!

[macds]

Im from Kitchener, Ontario

Started running like crap when we had that snow storm a couple weeks ago.

I was out bank bustin, and now she runs worse and worse!

grrrrr

 

Good to see another canuck on here!

 

Sounds like how my truck as running a year ago or so. Turned out to be a bad o2 sensor.

 

And welcome to

 

Where you from?

[cfar]

Im from Kitchener, Ontario

Started running like crap when we had that snow storm a couple weeks ago.

I was out bank bustin, and now she runs worse and worse!

grrrrr

 

Good to see another canuck on here!

 

Sounds like how my truck as running a year ago or so. Turned out to be a bad o2 sensor.

 

And welcome to

 

Where you from?

 

With a blocked cat,engine power should be greatly reduced and should have low vac above idle and wont rev up.

Remove the o2 and try to rev it up to confirm this if it is true.

 

I know its cold but try this or use a infared heat gun to check temp at manifolds-should be real hot +700* or glowing red at manifold or cat. if plugged

[macds]

Im assuming pre cat o2?

Also, which side is bank 2?? driver or pass?

 

Im from Kitchener, Ontario

Started running like crap when we had that snow storm a couple weeks ago.

I was out bank bustin, and now she runs worse and worse!

grrrrr

 

Good to see another canuck on here!

 

Sounds like how my truck as running a year ago or so. Turned out to be a bad o2 sensor.

 

And welcome to

 

Where you from?

 

With a blocked cat,engine power should be greatly reduced and should have low vac above idle and wont rev up.

Remove the o2 and try to rev it up to confirm this if it is true.

 

I know its cold but try this or use a infared heat gun to check temp at manifolds-should be real hot +700* or glowing red at manifold or cat. if plugged

 

[Bostonsfavson]

Maybe it's just a simple vacuum leak; check your hoses!

[asilverblazer]

Sounds like O2 is bad causing it to run way rich.

[macds]

Dealership has it this morning and says it one of the pre cat o2.

I have never had a vehicle run SOOOOO rough with a bad 02 before... WTF??

 

Thanks guys

 

now to pay the dealer$hit $375 for a new sensor.... damnit!

 

Stu