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Discussion Starter #1
Have an 08 Silverado with 4.8L motor. Recently got a misfire on cylinder #6 along with service stabiltrak/traction control. Changed plugs and wires misfired returned. Changed coil for #6, misfire returned. Service stabiltrak and traction control have been there throughout comes on and goes out. Truck has 68K miles and the 4.8 motor does not have the AFM. Any ideas, and have any of you encounter this type of problem. Happen right after I had to replace the belt tensioners but that seems unrelated. Any insight greatly appreciated.



Joe
 

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The intake manifold gaskets may be leaking sucking Rouge unmetered air in.
A Fuel injector may have failed.

It may be a sticking valve guide.
Burnt intake or exhaust valve.
Bad camshaft lobe.
Roller cam lifter failed.
Stuck piston rings.

Fuel injector not recieving power or ground.
Coil pack not getting power or ground from the ECM.

A cranking compression test is needed on #6 cylinder.
Checking all 8 cylinders a good idea.
 

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Discussion Starter #3
thanks. hoping it just an injector. There is no oil consumption, just a rough idle at times only when in drive. There are so many youtube and forum posts out there it's hard to try to find the right fix. I'll compression test the cylinder and such. Just don't want to get raped by a repair shop if it was something simple.
 

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thanks. hoping it just an injector. There is no oil consumption, just a rough idle at times only when in drive. There are so many youtube and forum posts out there it's hard to try to find the right fix. I'll compression test the cylinder and such. Just don't want to get raped by a repair shop if it was something simple.
I like to rule out mechanical potential issues.
Cranking compression test.
All good then move onto electronic driveabilty.

Check for injector pulse with a test light.
Check for Coil pack pulse trigger from the ECM with a Test light.
Can use a Noid light too.

Need a scanner that can do fuel injector balance test and a fuel pressure guage to flow test injectors accurate.
Expensive high end scanner like Snap On Used.

Shade tree way is process of elimination.
Works. Just takes longer.
 

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Discussion Starter #5
I wanna fix the misfire before going into the stabiltrak issue. Maybe fixing the misfire will clear the the stabiltrak I don't know. Truck has been problem free until now. Just frustrating.
 

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I wanna fix the misfire before going into the stabiltrak issue. Maybe fixing the misfire will clear the the stabiltrak I don't know. Truck has been problem free until now. Just frustrating.
Pretty Good Track Record so far.
The 4.8 V8 usually lasts 300,000 miles.

The 6.0 V8 gets beat to death here.
Mostly from towing.
Main bearings fail.

5.3 in Suburbans like to blow up.
Ran to death 90-100 in Chicago's crazy traffic on expressways.
Big truck and pretty small cubic inch engine.
 

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Discussion Starter #7
Maniac thanks for the help. Turns out it was a bad lifter. Always been a Chevy guy but this sours me alot. Truck has been well taken care of, Mobil 1 oil since first oil change, all routine maintenance performed and at 68K miles a lifter goes bad. Doesn't sound like the "longest lasting trucks on the road" to me. Next truck just might have a blue oval or a yota on it.
 

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Maniac thanks for the help. Turns out it was a bad lifter. Always been a Chevy guy but this sours me alot. Truck has been well taken care of, Mobil 1 oil since first oil change, all routine maintenance performed and at 68K miles a lifter goes bad. Doesn't sound like the "longest lasting trucks on the road" to me. Next truck just might have a blue oval or a yota on it.
Yes.
I have been seeing that issue with LS engines this year.
Go and Buy 1 quart of Marvel Mystery Oil.
Pour the entire bottle into the Engine crankcase oil.
Drive it.
If you have a safe backroad drive on it and get up to 80- 100 mph WOT.
Let off the gas and let the truck coast down to 20 mph.
Then repeat 1 or 2 more times.
See how the 4.8 LS engine runs afterwards.

Those Ford 5.0 Coyotes are Ok.
China Bullshit trans behind.
I had one apart 2 years ago.
Fried a piston from Super Charger Boost.
Pain in the ass timing the Dual Overhead Cams.
Screw up the procedure and its all over.

Toyota. Fick that ****.
 

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Discussion Starter #9
Top end is already apart being rebuilt. I'm the only one in my family with American vehicles. My brothers have toyota trucks that never need anything but gas. Sorry folks but this may be my last GM product. Love the truck but damn.
 

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Top end is already apart being rebuilt. I'm the only one in my family with American vehicles. My brothers have toyota trucks that never need anything but gas. Sorry folks but this may be my last GM product. Love the truck but damn.
Every engine had its issues.
LS I always felt had a Dinky Tiny Oil Filter stock.
LS does not tolerate Engine sludge buildup.
Lifters fail.
The Piston rings are ultra thin.
The Oil Ring piston grooves get clogged up with carbon sludge.


Mobil 1 is good oil.


I am a Castrol GTX Man.
Never has let me down. Been using since 1987.
Castrol Edge Full synthetic 10w30 is what I use in my own.
Even with old school flat tappet cams. Never Lost a cam lobe.


Oldsmobile built the best V8 for the street and lasted longer than all others.
Back in the day they led GM With the latest Technology.
Was not Chevrolet or Pontiac or Cadillac as most believe.
 

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Okay replaced all lifters and camshaft etc etc. How long til an oil change? 500 miles like a new car or go until the computer tells me to change it?
New engine or Cam & Lifters I like to change oil at 100 miles.
I have ran new engines on full synthetic on 1st start and ran fine.
Piston rings and cam and lifters were happy.

Depends what your working on and comfortable with.
Mobil 1 conventional 10w30 or Castrol 10w30 conventional oil a good choice.
Affordable.

In the Race shop I worked in last year I Lubed all cylinder walls and piston -rings assemblies with Castrol 10w60 Euro spec full synthetic oil.
Fired right up and rings sealed immediately.
Then put on Chassis dyno the cars to be tuned and Full throttle Power pulls made.

Just do not use a cheep bargain oil.
Will let you down.
 

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With old school flat tappet cams you change oil after 20 minutes breaking in the Cam and liftrers.


Your Chevy Silverado I would drive at 30-45 miles for 1/2 an hour.
Come back home and check for leaks.
100 miles change the oil and filter.
Good to go then.
 

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Try and find and use a K&N oil filter, Wix Gold Oil Filter, Napa Gold Oil filter.
The oil filter on LS engines are not large like old musclecar V8s.
Really dependent upon clean oil at all time.
K&N is my personal favorite.

The LS has a oil system bypass valve.
The way it works its open much of the time intentional.
So engine oil volume needs is met.
Oil is secondary filtered.

Done same way in a BBC , Ponch V8. Olds V8.
Full Oil Flow advertised .
But actually means what I stated above.
Bypass valve gets full of sludge your screwed.
Lose main and rod bearings.
Bad day then.
 
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