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2011 Very Rough Idle, Misfire on cyliner 7

Zman

SM 2003
Full Member
Joined
May 28, 2004
Messages
77
Location
NJ
My 2011 (with 16k miles on it) started idling rough again and triggered the check engine light. The code stated misfires on cylinder 7. I had the same problem 8000 miles ago for which the dealer replaced the spark plug.

I pulled the plug out. It was caked in burnt oil. I brought the truck back to the dealer. The dealer performed a service bulletin that required replacing the drivers side valve cover. The TSB stated the PCV system was redesigned via this new valve cover to prevent excessive oil pooling on the drivers side which leads to misfires on cylinders 1 & 7. The TSB had pictures of what the plug looks like, which looked exactly like my plug. Hopefully this fixes my flowed plug issue.

 
GM can't seem to figure out how to correct this and other problems related to the AFM system. The problems have been around since the '07 model year and I am sorry to see that they are still around for the '11 model year.
The "re-designed" valve cover seems to be used often and in my case, with the excessive oil consumption, did nothing  :E:
Keep an eye on your oil level between changes if you don't already. Check out the threads on this site concerning excessive oil consumption.
 
They can't test every thing, when they do a complete model change. Us older folks know not to buy a car/truck when its been redesigned.

Yes the 07 have some issues.
 
And 08 and if this really was a fix then the 11 should of already come with a pcv that should of been the correct on already. I had my rings replaced about 20000 miles ago so far about  1/4 of a quart at 5000 highway miles max oil change.
 
Mine is down ~ 1/2 a quart since the last oil change 2000 miles ago, which is pretty normal when you use mobile 1. I am down about a quart when I change the oil at 4500 miles or so, I do almost all city driving, so the oil change interval is fairly short. My understanding is that mobile 1 is a bit on the thin side of the 5w30 spec, so you burn more of it then a 5w-30 dino oil.

When I had my 2004, it was always down about a quart each oil change when I used mobile 1.
 
Redesigned valve cover did not fix my issue. The truck is idling rough again at times and the #7 plug has plenty of burnt oil on it. Time for another trip to the dealership.

This is the least reliable vehicle I have ever owned. I have had it for 1.5 years and have had to bring it back to the dealer 5 times already for a wide assortment of problems. The worst part about the issues is my local dealer doesn't want to do warranty work on it since I didn't buy it from them, so I end up driving 60 miles to the dealer I bough it from. Between the poor reliability of this truck and the poor dealer experience from my local dealer, Chevy is losing me as a customer.
 
That's too bad Zman but I understand why you are doing it.
 
Ugh, wish I read this before I posted a new topic... I had my 2007 taken in for this exact issue and they replaced the cover. And from the sounds of it, it doesn't change anything and my problem will return  :E:  :E:

Seriously GM, this is becoming a joke...  :rolleyes:
 
I had visited the dealer multiple times for fouled plugs on 1 and 7.  During my last visit, they changed the valve seals and told me it would correct the problem.  We shall see... 

 
Plenty of miles on my '07 with the original valve cover and doesn't burn excess oil and runs smooth as silk......new engine change Mobil 1/filter at 1K 3K and 5K then after every 3K max and air filter every 10K...add upper valve lube every 3 tanks of gas. Mixed driving, always recover at least 5-1/2 of the 6 quarts in the system. Pooling oil in a valve cover won't do anything toward plug fouling unless the valve seals are leaking and then it gets sucked past the valve stems into the combustion chamber. Bad valve stem seals cause both excess oil consumption on the affected cylinder(s) and fouling of the related plugs.....seal replacement should have been the first fix tried and should fix both problems.

Once had the problem in one cylinder on an old V8 and was to lazy to replace the valve stem seal. Not sure if they still make them, but last resort would be to use a plug adapter/extender....same thread as the plug....fits in line with the plug.....shields the plug center electrode and has a hole in the bottom to ignite the mixture.......plug will then fire in oil condition without fouling for an extended period. Usually lasted the 10K life of the plug changes used in those days. Worst cases required a Doering brand spark plug designed to fire in oil and it did just that .....not sure if they make emission compliant versions, but you could run one in a leaky cylinder and never have it foul.

I thought that the days were gone when dealers discouraged warranty work on vehicles purchased elsewhere...must be a jerk and you wouldn't want to buy from them anyway..I use 4 Chevy and GMC local dealers in MD and WV and they all give me excellent warranty service for my Avys even if purchased elsewhere and seem happy to get it and provide free coffee and donuts, TV and computer access to boot!...even went out of their way to expedite shipment of replacement parts. The only additional breaks I get if I use the dealer where purchased is free State inspections, discount on parts and loaner if needed.
 
Zman said:
Redesigned valve cover did not fix my issue. The truck is idling rough again at times and the #7 plug has plenty of burnt oil on it. Time for another trip to the dealership.

This is the least reliable vehicle I have ever owned. I have had it for 1.5 years and have had to bring it back to the dealer 5 times already for a wide assortment of problems. The worst part about the issues is my local dealer doesn't want to do warranty work on it since I didn't buy it from them, so I end up driving 60 miles to the dealer I bough it from. Between the poor reliability of this truck and the poor dealer experience from my local dealer, Chevy is losing me as a customer.

Take it to another dealer. The issue is the AFM- Active Fuel Management. There is a fix where they put a shield in the Lifter Valley.

Avalon
 
avalonandl , do you have any more information on that fix. I hadn't heard about a shield in the lifter valley before.

My dealer stated there is a TSB for a shield for the bottom half of the engine to prevent oil from getting on the cylinder walls. I don't have confidence in this patch either.

GM handling of these AFM issues related to burning oil are ridiculous. It is a good way to lose long time customers!







 
Irrespective of whatever else you do, with what is known about this problem now, at the first hint of a problem and preferably before...Turn..Off..AFM.
 
avalonandl said:
Take it to another dealer. The issue is the AFM- Active Fuel Management. There is a fix where they put a shield in the Lifter Valley.

Avalon

That would be incorrect. There is a secondary oil pressure relief in the oil pan, that is where the shield goes.



If you all under stood how the AFM engines work, you'd understand the oil consumption problems. Why GM just hasn't done away with it I dont know.

The AFM engines have piston squirters to keep things cool. When you turn off a cylinder, there is no pressure on the rings to wipe the cylinder wall clean. ergo you end up with oil in the cylinder. Cylinder 1 and 7 are the AFM cylinders on the left bank. For whatever reason crankcase pressures are higher on the left side, which also leads to oil consumption. It all adds up to be quite the pain in the ass.  The only full proof way to beat the oil consumption is to get AFM tuned out.
 
krazycarguy said:
That would be incorrect. There is a secondary oil pressure relief in the oil pan, that is where the shield goes.

I am getting ready to take my 08 LC9 in for them to clean the combustion chambers, drop the pan and do the revision and then put me on the oil consumption monitor, but I am not holding my breath it will make any difference.
GM's next step after this would be pistons and rings.
They could save everyone a lot of time and hassle (and themselves a lot of money) by simply turning off my AFM.
 
Yes turn it off, unfortunately you have to buy a tuner but it's cheaper in the long run. I used diablo and turned mine off. Not really sure exactly why but my gas mileage increased on some of my tanks, maybe because of cleaner plugs. I say on most tanks because sometimes it goes back to the same old mileage. I know its off topic but I have an ap that shows fuel trims which are varying and show the truck running rich, maybe the gas I get sometimes.  ???
 
I'm at the point now where I need to get the system disabled but I have no idea how to go about doing that... any suggestions? I don't know or even understand anything about the tuning stuff, I'm a complete newby! Is it something I can do myself from home or something? I'd rather spend whatever it costs to get it done than have to buy a new vehicle. I love my avy too much!  :love:

Update: Is this something I should look at getting??? http://www.truckcustomizers.com/products/superchips-cortex-programmer-chevy-gmc/3-2950.html
 
if you have no knowledge at all i would just take it to a respectable tuner. Someone that knows what they are doing.

LornesAV said:
Yes turn it off, unfortunately you have to buy a tuner but it's cheaper in the long run. I used diablo and turned mine off. Not really sure exactly why but my gas mileage increased on some of my tanks, maybe because of cleaner plugs. I say on most tanks because sometimes it goes back to the same old mileage. I know its off topic but I have an ap that shows fuel trims which are varying and show the truck running rich, maybe the gas I get sometimes.  ???

Are your fuel trims positive or negative and by how much?
 
ca2kjet said:
I'm at the point now where I need to get the system disabled but I have no idea how to go about doing that... any suggestions? I don't know or even understand anything about the tuning stuff, I'm a complete newby! Is it something I can do myself from home or something? I'd rather spend whatever it costs to get it done than have to buy a new vehicle. I love my avy too much!  :love:

Update: Is this something I should look at getting??? http://www.truckcustomizers.com/products/superchips-cortex-programmer-chevy-gmc/3-2950.html

pm sent
 
krazycarguy said:
if you have no knowledge at all i would just take it to a respectable tuner. Someone that knows what they are doing.

Are your fuel trims positive or negative and by how much?
sorry for the  :jacked:
Man they are all over the place. They are negative all the time usually at -5. The trip from Jonesboro to Little Rock last night they went to -7. I filled up with 89 a few minutes ago and they were around -9 -10 (not much driving yet). This round was the worst gas mileage I have ever had at 14.4. The DIC had me at 25.8 gallons I put in 30 that is way off from the typical 1 gallon and lately on the money. I usually run bad fuel trims when against the wind but driving SW last night I should not have been. Quite honestly tho I knew my gas mileage would be down without the fuel trims. Maybe unrelated but it doesn't seem like it that when the wandering steering gets worse so does the MPG. The truck doesn't always wander this bad. Since the tires were rotated it's been worse, this weekend I am changing them back to see of I am crazy. For the complete info I am running a K&N CAI and diablo can tune (mpg boost)
 
How many miles are on your truck and where do you normally get gas? Maybe you have a slow leaking injector. I only get gas at BP, Shell or Kwik Trip. They are the only ones around here that use top tier gasoline. And actually GM recommends top tier gas.
 
Usually Shell, Mobile or BP but not 100%, every once in awhile QT.

149000 but this has been the case for many thousands of the miles. I have bought cameras to record stuff underneath the truck to see what the issue is. Just bought some rulers to see if the truck spring or something is changing the hieght at I drive. It feels like a vehicle from the 70's if your old enough to know.  Also have sway bar end links that loosens up and get chewed up and they are poly. But everyone says the stuff underneath is fine.  :bsflag:
 
The dealer did the update to the TSB that I had done previously which replaced the drivers side valve cover. The update was to add a shield to the AFM relief valve in the in oil pan, replace the plugs, do the engine cleaning procedure.... I had asked the dealer if they ran any tests on my truck, ie compression, etc because I was concerned the rings are bad. They said they can only do what GM tells them to do, which in my case is to install the shield and do the cleaning procedure. The TSB states if this does not fix the problem, then all of the pistons and rings need to be replaced. This is pretty discouraging that the TSB itself isn't confident that this shield will fix the problem.

With ~ 100miles on the truck since the latest TSB was applied, it is starting to stumble while idling already. With the other two attempted repairs, it took a couple thousand miles before it ran rough. What is really annoying about this shield is that my dealer stated the TSB was updated October 2012 to include install this shield, but it states engines built after October 2010 already have the shield installed. Why did it take two years to update this TSB to install the shield for my vehicle. I feel like my truck is a guinea pig for GM.

I will pull the plugs out in a couple of weeks to check for oil fowling.

Note, I will not turn off AFM and void my warranty, realize this is a 2011 with 21k miles on it.

 
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