2004 Denali 6.0L throwing Codes P0174, P0171, P0101, P0446

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

HiHoeSilver

Away!
Joined
Feb 28, 2017
Posts
10,919
Reaction score
14,571
Location
Chicago
Update: Used buddies non-leaking pressure gauge, 48 psi with key on but holds steady, and when started it jumps up to 58 and stays right there, whether at idle or revving the engine up. I am going to replace the air filter and fuel filter both, but I don't think that is going to fix my lean condition. I think it's time to check the intake bolts and look for an intake leak. I will also check the other things you all just talked about, I appreciate it. More updates to follow as I will have some time to work on it this weekend. Thanks.

Jeremy

Did you clear the codes?
 

afpj

Full Access Member
Joined
Sep 16, 2009
Posts
779
Reaction score
308
Did you check fuel trims at idle, and at around 2000 rpm? Oxygen sensor voltage graph/pattern?
 

BlueCollarTahoe

Full Access Member
Joined
Sep 21, 2016
Posts
538
Reaction score
112
i had a similar issue but running rich...turned out to be the Oxy sensors.
 
OP
OP
M

Marinevet

Member
Joined
Feb 2, 2016
Posts
30
Reaction score
4
That makes sense to me. Where is the evap purge solenoid located on the truck, and is there any way to test it, or should I just replace it? I already blew off the MAF sensor, so I will check the evap purge solenoid next. I didn't get to the Yukon this weekend, I hope to either tonight or tomorrow night. Thanks again for the help.
 
OP
OP
M

Marinevet

Member
Joined
Feb 2, 2016
Posts
30
Reaction score
4
Did you clear the codes?

I didn't clear them yet, I want to get the new air filter and fuel filter in first, but I didn't get to it this weekend quite yet.

Did you check fuel trims at idle, and at around 2000 rpm? Oxygen sensor voltage graph/pattern?

I am not able to check that stuff, I just have a code reader, not an actual scan tool. I don't mind paying someone to hook one up, but first I want to rule out all the things I can check myself without the scan tool.

Thanks again for all the input everyone.

Jeremy
 

Rocket Man

Mark
Supporting Member
Joined
Dec 25, 2014
Posts
25,961
Reaction score
50,621
Location
Oregon
I believe fuel pressure should be around 58 and no drop in pressure.(maybe 5lbs) we don't have a fpr on the fuel rail as it's in the tank with the pump. Sooner or later the pump will completely give out so might as well change it now and fix that evap while your down there
Actually the fpr is on the intake manifold. Don't remember exactly where but I remember removing it to reinstall on the fuel rail of my Whipple. It looks like this.

217-3299_Primary__ra_p.jpg
 
OP
OP
M

Marinevet

Member
Joined
Feb 2, 2016
Posts
30
Reaction score
4
Actually the fpr is on the intake manifold. Don't remember exactly where but I remember removing it to reinstall on the fuel rail of my Whipple. It looks like this.

217-3299_Primary__ra_p.jpg

From everything I have read, this was prior to 2004. In 2004 they went to a returnless fuel system, where the regulator is actually in the gas tank.
 
OP
OP
M

Marinevet

Member
Joined
Feb 2, 2016
Posts
30
Reaction score
4
To be honest I haven't played with my newer Tahoe, but I bought a cheap bluetooth scanner that you use with your phone and Torque or some similar app.
On my last one it surprised me how much data was available. I originally bought it to try to work on towing mileage.

https://www.amazon.com/s/ref=nb_sb_ss_i_3_7?url=search-alias=automotive&field-keywords=obd2+bluetooth+scanner&sprefix=OBD2+bl,automotive,227&crid=2L70ZZGVK6S0U

Do you remember which one you actually ended up buying? Those are cheaper than I thought they might be.
 

Rocket Man

Mark
Supporting Member
Joined
Dec 25, 2014
Posts
25,961
Reaction score
50,621
Location
Oregon
From everything I have read, this was prior to 2004. In 2004 they went to a returnless fuel system, where the regulator is actually in the gas tank.
According to Rock Auto that one in the picture is for a 2004 but they could be wrong.
 

Forum statistics

Threads
128,801
Posts
1,805,623
Members
91,784
Latest member
navyboy14094
Top