My Experience so far with 2007 Yukon. Idle issues after cam swap, P0300, P0420, tuning.

[Sam Harris]

Hope you can get that tuned ASAP, before it causes any more problems, and expense for you.
By the way, welcome to the best forum on the internet, from East Texas!
Please post some pictures of your rig. We like pictures..!

 

[OklabyGodhoma]

I'll add my welcome as well, sounds like you will bring some knowledge to the forum with you. I am currently throwing that dreaded P0420 code as well after done a DOD release. Not experiencing any of the other problems you are but not looking forward to pulling the O2 sensor and putting the camera down the pipe. Interesting about the Magnaflow because I was already looking at getting one. Hope you get to the bottom of everything and please don't give up on your Yukon. Except for the stupid idea of the AFM it has been the best vehicle I have ever owned as a daily driver but of course living in Okla-byGod-homa I don't have rust to contend with; just tornado's and heat.

Welcome again!!!

 

[FasterBass]

Adding in some BTR stage 2 came experience WITH valvespring change. I went Blackbear from day one and they have been nothing short of amazing. Every tweak I make, I send them ONE log and get back an awesome tune. I actually wanted a little lope with the stage 2 cam and got it, but not with any kind of drivability issues or hard starting. I have a Air Raid intake tube that connects to the stock filter housing and a high flow filter as well. 0 issues. Its all in the tuning.

 

[BG1988]

Nurse it over a couple of blocks to the auto parts store, purchase a new coil and swap it out. No change.

So, nursing the truck along closer to home (3rd mistake), I decided I better park it and walk the rest of the way. Go back later with some tools and test equipment and find that the whole driver side bank of cylinders is stone dead! No spark on any of them 1,3,5,7. Luckily this is a fairly common problem with the 5.3 as there are multiple videos of this on YouTube. Running a new ground wire the bank of coils gets the truck running on all cylinders again. Great! Get the truck home, go over, and repair all the grounds on the engine, and I thought I was done. G102 is the culprit for this symptom btw in case anyone needs that info. It is on the engine block behind the power steering pump bracket.


Now I can drive it knowing it will not leave me high and dry at the side of the road.

After some nice highway cruising one morning, the check engine light pops on. Hmmm. Plug in the code reader expecting to see a p0300, but instead I see the dreaded p0420 for the bank 1 converter. Great.

Upon further investigation, and after trying to space out the B1S2 O2 sensor with no success, I stick a scope in the O2 sensor hole and aim it at the catalyst. Well wouldn’t you know, the catalyst is completely destroyed. All busted up, it must have melted from the raw fuel dump when trying to get the truck home running on only one bank of cylinders. This ones on me and I really should’ve known better. But to be fair, I did not realize at the time that 4 cylinders were dumping fuel down the exhaust. I thought it was only #1 cylinder and I had unplugged the injector while limping along.

you should have disconnected the fuel injectors if it was dead completely on one side of the engine then limped it home... tow truck..


i made that mistake and fried my Cat on my old car but i only went a mile...

 

[ouch_my_L4L5]

I'll add my welcome as well, sounds like you will bring some knowledge to the forum with you. I am currently throwing that dreaded P0420 code as well after done a DOD release. Not experiencing any of the other problems you are but not looking forward to pulling the O2 sensor and putting the camera down the pipe. Interesting about the Magnaflow because I was already looking at getting one. Hope you get to the bottom of everything and please don't give up on your Yukon. Except for the stupid idea of the AFM it has been the best vehicle I have ever owned as a daily driver but of course living in Okla-byGod-homa I don't have rust to contend with; just tornado's and heat.

Welcome again!!!

Thanks! I bought the Flowmaster converters not the Magnaflow. I've since returned them and gone back to stock. Good luck with your P0420! Get yourself and O2 thread chaser before you pull out your sensor as they sometimes wreck the threads coming out.

 

[ouch_my_L4L5]

you should have disconnected the fuel injectors if it was dead completely on one side of the engine then limped it home... tow truck..


i made that mistake and fried my Cat on my old car but i only went a mile...

Hindsight is 20/20 as the saying goes. I didn't know the whole bank was dead at the time cause that would've been a great idea! The ECM only informed me of a random misfire p0300.

 

[ouch_my_L4L5]

General update on the Yukon: The truck runs great! As a daily driver/hauler I should've opted for a more low end torque cam instead of the BTR Stage 1 performance. Long trips on the interstate is where I really feel the difference with the new cam. Just when you think you've maxed out, just push the gas down a little further and this thing just wants to go fast! Need to be careful I don't get nabbed for speeding. Overall I got more than I bargained for with all the little gremlins I got to gently massage out the vehicle. But I got the truck to where I want it for now and it has turned out to be a reliable daily driver. Coming over from the 03 Tahoe was an adjustment and I was comparing the two trucks thinking they were the same beast. While they share many similarities, once I got my head wrapped around the fact that they are in fact not the same truck, it was easier to accept the differences. Will add some pics soon. The truck is bright white so it's real hard to keep clean!