need help

[pooperscooper]

i have a 14 yukon denali with a 6.2L. i have a few codes and i don't know how to fix the problem. i don't nkow are the code numbers but some are bank 1 and bank two system too lean. multiple cylinder missfire. and i believe the one code that is listed as permanent is a p0174. if i remember the code right its for the pedal sensor. the yukon had had the gas pedal replaced 4 times (its easy to do and i have friends that work on silverados\sierras and tahoes\yukons so we have plenty of extras). ive put three different 90mm throttle bodies on it and checked\cleaned the maf. all issues keep coming back.

the truck at start up is going into reduced power mode, stabilitrack turns off and traction control turns off. the rpms fluctuate and even at times sound like its got a cam. check engine is not flashing when it does this.

my friend has tuned the vehicle like he has all of my others, but he didn't changed anything with the performance of the truck. he just turned off dod and (idk what its called) a system in the pcm that regulated if the truck was running on e85 or gas. i found that some models have an actual sensor for that but mine apparently doesn't. the truck was running poorly and it was bc the truck kept thinking it was running e85.

any help or suggestions will be greatly appreciated and i will be available for any questions. thank you

 

[wjburken]

Post all the codes you are getting. The more information you share the better folks here can help.

P0174 looks to be fuel/air ratio is too lean, not pedal sensor.

Dont be too quick to dismiss how your friend modified the tune in your vehicle. Not discounting your friends ability, but even the best make changes that cause issues they didn’t expect.

 

[pooperscooper]

Post all the codes you are getting. The more information you share the better folks here can help.

P0174 looks to be fuel/air ratio is too lean, not pedal sensor.

Dont be too quick to dismiss how your friend modified the tune in your vehicle. Not discounting your friends ability, but even the best make changes that cause issues they didn’t expect.

ty for the imput. once he is back in town in going to get him to go back to the default tune to see what happens. i don't have the ability to get codes atm. my friend is out of town atm and i cant drive the vehicle in limp mode with all the trafiic on a holiday weekend

 

[j91z28d1]

you're probably going to need to figure out why it's missfiring first. you might have to invest in some tools. a scanner to see some data while it's happening and tools to trouble shoot from there. like pull the plug in that missing cyl, see what it looks like. do compresson check, just because dod/afm is off, the lifters still fail.

check for grounds, engine and coil pack ground. check for spark. basic stuff like that..


if you guys have a bunch of the same Gen trucks around and keep throwing throttle pedals at them in hope it fixes it. it might be time to pick up a tech 2 and a subscription to all-data to share.

hptuners has a scanner built in, but it's super limited when it comes to actual trouble shooting and you'll need access to the dealer level trouble trees to really fix the hard to find stuff. if you find yourself replacing the same part over and over, it tends to be harness or module problems from my experience.

 

[89Suburban]

pooperscooper? ahaha

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

As @j91z28d1 stated above, you should invest in a quality bi-directional scanner, as this tool will greatly help you zero in on the source of your issue. Otherwise, you'll just be firing the parts cannon at the truck with the hope of resolving your issue.

 

[Fless]

pooperscooper? ahaha

Lots of poop around here to scoop.

 

[pooperscooper]

codes are p2128, p2138, p0174, p2127. i dont have any pic of the truck but ill take some later after i get done with my honey do list. glad you guys like the name!

 

[alpha_omega]

All of your codes seem to be related to the pedal position sensor and/or the connection between the ECM - Throttle/Pedal Position Sensor.

When you replaced the throttle body, was it replaced with an OEM GM throttle body or an aftermarket? Just curious…Not that it necessarily matters which, given that even the sensors GM uses on the TB have their flaws. Also, what are you using to clean the MAF sensor and throttle body. How are you cleaning it?

Have you checked all of your grounds? ALL of them? If not, check every single one, remove them from the mount, clean that mounting location and then reinstall. This will also help you to determine if any of the ground wires are bad.
Have you traced the wires running to the TB, in order to determine that the harness and its wires are in good shape? Same goes for the pedal.

When replacing the pedal sensor, was that done with new parts or an old one swapped from another vehicle? Not that this needs to be brand new, it’s just helping us to help you diagnose the issue.