RPM fluctuation at cold

[morrislee]

On cruise, I have a slight RPM fluctuation at start of a colder day, I have been getting he code P050D for Rough Cold Start (which is bad enough that I can notice when the code will trigger)

 

What could be the problem?

 

Truck is Sierra 1500 2014 with 5.3L ecotec3

 

If it is injector, what test can I run to narrow it down without taking off the intake manifold?

 

If it is the sparkplugs, how do I test them?

 

Please assist, thanks!

[Jsdirt]

Interesting. Thanks for the info.

[morrislee]

Requires a cold start. Can't really actually test the injectors for this specific condition. Cold start and GDS2.

 

How did they go about testing the injectors here? http://www.performancetrucks.net/forums/gmt-k2xx-trucks-general-discussion-221/p050d-code-533167/page2/#post5287545

 

Are there any standard injector testing tools at the dealership?

[morrislee]

Had to order parts. Seems like it was 2-3 hours + diag. Not sure though. If anyone but a dealer does this repair, you need to replace the fuel lines that are removed. They are one use only. Dealer should know this. Others may not.

Could you please list the part numbers replaced? I want to make sure if they did the same procedure, the fuel line you are referring to is also covered. How long did it take to order? If my injector is bad, do the dealership put the truck back together until the part arrives or am I going to have to leave it disassembled there until part arrives?

[Jsdirt]

Nope - mine's too old.

[morrislee]

Just got the P050D code yesterday. Got it once before also about a month ago. Will have the dealer look at it when they call me for the trailer hitch recall. So far its only happened on cold days when remote starting. Hopefully no internal damage is caused by this.

 

If you can get the code to repeat, get it checked out next time when it shows up, demand something to be done before you get it back as the code is reoccurring.

[Jsdirt]

That's good. Sounds like that may have been all it was. Why on a brand new truck, I don't have an answer for ... but at least it's fixed and you're happy. That's all that really matters at the end of the day.

[morrislee]

I had to search the net for that one - never heard of a code ending with a letter ... but it seems this is a thing now.

 

Just from what I've seen on Google, everyone that has this code has a CAI & other mods, and/or ran E85. One guy said GM threw a new set of injectors in, and that fixed it. Another possible cause is carbon buildup on the intake valves due to the new DI.

 

Pretty sure it is related to my other problem where the RPM fluctuate on highway and eventually the TCC opens for more slipping to allow more fuel flow on cruise. dealer could not reproduce the RPM fluctuation issue and unable to do anything. sick of wasting time on them.

 

How many miles on the truck? It would appear that you should still be under bumper to bumper warranty time wise, but may be out miles wise. If you are still under the 3 year warranty, let the dealer fix it.

 

I read on one site that GM is running the 5.3 engine with Active Fuel Management on 4 cylinders when idling. That has to create a different sounding and running engine compared to the non Active Fuel Management engines on the 2014 and newer trucks.

 

passed the 60,000km warranty (Canada) and V4 is disabled. My other code was P219A and both of these codes has been fixed by a street tuner right now, but the RPM fluctuation is probably related to P050D and I was wondering if anyone has any thoughts on the code.

 

BTW, truck should not normally be idling at V4 especially when it is cold. If yours is doing it, I think it has to do with this recall http://www.autonews.com/article/20140110/RETAIL05/140119956/gm-recalls-303000-new-chevy-silverado-gmc-sierra-pickups-for-engine

[rrimportracer]

update on this.

 

After a few calls to corporate, my local chevy dealer replaced the torque converter. Issue resolved.

[SouthernSilveradoGuy85]

How many miles on the truck? It would appear that you should still be under bumper to bumper warranty time wise, but may be out miles wise. If you are still under the 3 year warranty, let the dealer fix it.

 

I read on one site that GM is running the 5.3 engine with Active Fuel Management on 4 cylinders when idling. That has to create a different sounding and running engine compared to the non Active Fuel Management engines on the 2014 and newer trucks.

 

The 5.3 in my '14 with almost 24,000 miles doesn't do anything like that in 4 cylinder mode. It still runs smooth no matter the temp and switching back and forth is also still smooth. Before I had the exhaust done the only way I knew it was even in V4 mode was by looking at the dash. I don't think his problem has anything to do with AFM.

[Jsdirt]

Same with my '07 - switching was always seamless. I could tell when it switched, but nobody else could.

[tbarn]

2 12668649 injectors

1 12618336 pipe

1 12618337 pipe

1 12672366 injector seal kit

8 12626354 intake seals

None are covered under powertrain, only 3/36

[rrimportracer]

I have the issue with my truck fluctuating RPMs but much more quickly than you're describing.

 

 

 

 

 

 

in the first video instead of a smooth power band, the truck seems to spurt power every few seconds. in the second video you'll see rapid fluctuations under light load. I've taken it to the dealership and they said there's a lot of fluctuation in the TCC slip speed, but that it was normal.

 

This is most annoyingly happening when I'm trying to climb an incline and it's shifted into a higher gear. How is this normal?

It only does this in the lower RPM ranges, as soon as I get it to about 2000 it's fine. No misfires, no codes, just the annoying jerkiness.

[morrislee]

Fixed!! They also called in the regional manager if I remember correctly, and waived the $200 deductible!!

 

My problem i have listed at this post is also fixed because of this posted here:

 

http://www.gm-trucks.com/forums/topic/181145-2014-53l-6-speed-rpm-fluctuations/

 

 

Thanks everyone!

[tainoxl]

Code came back yesterday afternoon, truck goes in on Monday. We will see how this goes. Has to be a bad batch of injectors from GM going around.

I can see this turning into a tsb in the future.

[Jsdirt]

Good deal - glad to hear it!