05 gmc yukon xl slt

[Bipolaryukonxl04]

i have hey 2005 GMC yukon xl slt but it is all wheel drive. Supposedly only denali have all wheel drive. So I have issues I cannot get the four wheel low to go in but that's alright so the problem I have is actually error codes and I get a lot of multiple misfire going on and O2 sensors going off of lean codes all all four of them any suggestions. And another thing I was wondering so I replaced the coil springs gained an inch but still fremeaux when hauling a trailer I kinda need it stronger but I don't know how what should I do

 

[drdave81]

AWD was only available on Denalis and Escalades. To know quickly, if you have the 4WD switch on the left side of the cluster, you do not have AWD.

Tell us which codes you have and we can help.

If you're hauling a heavy trailer you really should be using a weight distribution hitch. Lots of us have also used helper bags inside the coils for that too.

 

[Bipolaryukonxl04]

i have all wheel drive only options i have are 4 low all wheel and no traction control...

codes are... p0137, p0156, p0157, p0171, p0300, p0131p, p0156p
when maltipal misfire code reads the cel blinks if i punch it i feel all cylenders hit right and im back at 20 mpg. or better... i have 229000 miles on it i baught it 50,000 miles ago. i replaced the coil springs that helped just curious about the helper bags

 

[Fless]

Look at the inside lid of your glovebox at the RPO codes. Do you have NP8, or NP2?

When was the last time the spark plugs and oxygen sensors were replaced? Was any recent maintenance done right before this all started?

Cleaned or replaced the MAF? Air filter good? Throttle body clean? Checked long- and short-term fuel trims?

 

[Bipolaryukonxl04]

changed spark plugs and wires not long ago fule filter and bout to do the fule pump soon 43 psi was shutting off on me on my 4 hour rides weekly started with plugs and wires then fule filter it helped but still get these codes and the misfire untill i put it to the floor litterally and i will go see what rpo codes i have the maf will come net too

 

[drdave81]

Based on having a P0300, mult/random misfire, a P0171 - system lean bank 1 and a whole shit load of O2 sensor codes, im going to throw out a guess you have a nasty misfire causing everything. Do you have access to a scan tool to read data? You're going to want to see misfire monitors, fuel trim data, etc to really pin down what is causing this.

Edit, just saw your comment about the vehicle shutting off during long drives. Make sure you have a pump issue and get the pressure issue resolved. Clear codes and see what happens after that.

 

[Bipolaryukonxl04]

i clear codes and it does not thro another code for a cupple days some times weeks and hasnt shut off since i changed the fule filter i cleared codes last night and it drove great today this is where i get confused.

 

[Bipolaryukonxl04]

 

[drdave81]

Do you have access to a scan tool that can read data? You need to look at some actual data to find out what's going on, such as: Is your misfire all over the place, or does it stay at certain cylinders? What are your fuel trims showing? If you don't have access to one, you may have to have a shop check it out for you.
You said you have low fuel pressure, 43PSI. Was that before or after changing the fuel filter? Record your pressures at key on, running and check it 10 minutes after key off.

 

[Bipolaryukonxl04]

ill see if i can get one. thanks