2015 Tahoe, P050D Code (cold start rough idle)

[ReaperHWK]

Some history first.

1)Few weeks ago on a trip home the Tahoe threw a code, it was a P0300 Random Misfires. I could tell it was running rough. I replaced all the plugs(truck has about 120k miles) and it ran much better. P0300 went away.

2) A few days later it then threw a cylinder 8 misfire code(forget the number). I used my scanner and did see that 8 was misfiring even with a new plug so I replaced the coil and the wire. Misfire cylinder 8 went away and never came back.

3)Truck runs like a beast when it's warm, I run full throttle and many part throttle runs the truck runs great and doesn't set ANY misfire codes anymore. A few days later(after I think I'm 100% with the truck), it throws a P050D code which means cold start rough idle. I do notice now that on cold starts, the engine does run rough and sputter a bit for like 5 seconds. After that the truck runs like a champ.

4)Looked online for what could cause this, and I did the following with no success yet. Cleaned the MAF, cleaned the TB, used CRC intake valve cleaner, and also used fuel injector cleaner. Stuff was dirty but after I clear the P050D code it still comes back.

Any tips for what to try next? I read online it could be a faulty fuel injector but I'd like to do that as a last resort because I'd have to pull the manifold and they aren't cheap. I can't pinpoint a misfiring cylinder either so I'd have to do all 8....

 

[ReaperHWK]

Anyone have this code before and fixed it?

Latest is I drove for a few days, seems like all cylinders have either 0 or a max of 2 misfire counts(good) except for cylinder 8. Reading 63 misfire counts, so there is something up with that cylinder. I decided to replace the plug in #8 again, maybe I got a bad plug? Sucks is that #8 is the WORST plug to get access to.

If that don't work I'm going to suspect its a faulty injector. But if I'm pulling the intake I'd just do all 8 while I'm there....................

 

[ReaperHWK]

Finally got around to changing #8 plug, cleared codes, and did some logging no #8 misfires yet. Hopefully it was a bad plug.

If it's not then it's the #8 injector, I'll have to wait on that job though looks time consuming.

ANyone have any tips for changing the injectors? Should I just do the one or the whole rail on that side?

 

[GeoffM]

Oh hey sounds like you and I are in the same boat!

If you pull the injector rail per side you will need to replace the seals on the injectors. So it makes sense to do a side at a time.
For me, I'm kinda pissed off at my dealer and also that my new (to me) truck is having issues. So, I'm doing all of them at once.
(And also off of Rock Auto they're $40, not $110 like local).

One thing to note: Injectors are not all the same. You must read the code printed on the side of the injector to order the correct one.

 

[ReaperHWK]

Oh hey sounds like you and I are in the same boat!

If you pull the injector rail per side you will need to replace the seals on the injectors. So it makes sense to do a side at a time.
For me, I'm kinda pissed off at my dealer and also that my new (to me) truck is having issues. So, I'm doing all of them at once.
(And also off of Rock Auto they're $40, not $110 like local).

One thing to note: Injectors are not all the same. You must read the code printed on the side of the injector to order the correct one.

I’m about to order either one or 4 injectors and to the passenger side rail. When I look for the injector there is only one part number for tje injector for my VIN. What do you mean I can’t order the injector without looking at it?

 

[GeoffM]

I’m about to order either one or 4 injectors and to the passenger side rail. When I look for the injector there is only one part number for tje injector for my VIN. What do you mean I can’t order the injector without looking at it?

2016 GMC YUKON XL 6.2L V8 Fuel Injector | Shop Now at RockAuto

Fuel & Air Parts and More for Your 2016 GMC YUKON XL at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

That's the link for mine. See how it shows different injectors marked with ####?

I had read on a different website (forgot which one) that the normal/nominal/high flow has to do with emissions. Idk, that's what the dealer told me. They also said you're supposed to replace the fuel lines betwixt the injector rails because they can leak if they're reused. I bought mine from Rock Auto, which now shows as OOS.

 

[ReaperHWK]

2016 GMC YUKON XL 6.2L V8 Fuel Injector | Shop Now at RockAuto

Fuel & Air Parts and More for Your 2016 GMC YUKON XL at Reliably Low Prices. Fast Online Catalog. DIY-Easy. Your Choice of Quality. Full Manufacturer Warranty.

www.rockauto.com

That's the link for mine. See how it shows different injectors marked with ####?

I had read on a different website (forgot which one) that the normal/nominal/high flow has to do with emissions. Idk, that's what the dealer told me. They also said you're supposed to replace the fuel lines betwixt the injector rails because they can leak if they're reused. I bought mine from Rock Auto, which now shows as OOS.

I see that your right about the lines. I’ll order them too. I still can only find one ac delco injector for my VIN but I’ll verify again with the dealer. Tha ks

 

[ReaperHWK]

So talked to dealer again today and they said for my VIN there is only one AC delco PN for the injectors. I ordered 4 decided to do the whole passenger rail and then I won’t have to mess with the seals as they all come assembled. But yes the dealer confirmed I need those 2 high pressure fuel lines and also the intake manifold gaskets. Ordered those as well.

It was around $600 for all those parts. Know I could have gotten them cheaper but it’s all OEM. That’s for 4 injectors, new fuel lines, and manifold gaskets…..

Time for fun!

 

[ReaperHWK]

Just to close this thread the replacement fuel injectors completely fixed this issue. Car runs better than it ever has for anyone else with a p050d