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08 silverado 6.0l vortec not going into afm mode

7K views 20 replies 9 participants last post by  racer7696 
#1 ·
Hey guys I have a 08 6.0 l engine and it is not going into afm or the 4 cyl mode when coasting down hills and no load at all on the engine.At idle it goes to 0 like always but when you get up to speed and take your foot off the gas on the highway going down a big hill nothing .the reason im worried is that chevy has already replaced my lifters three times on this truck they have had two generations of lifter changes and one time they had to go back in cause the only did one side two months earlier.It has been 15,ooo since last done and the engine has felt a little flat on the bottom end .So my gut is telling me something might be going on with the right bank of lifters the ones that pump up and keep the valves closed.Anything else cause this condition. Thanks Mark
 
#6 ·
The 6.0 never had AFM. And I also don't think there was anything to tell you you were in v4 mode. That just came out on the 2014's.

If you are 100% sure you have AFM then you must have a 5.3. That was the only engine that came with it on the gmt900 platform.

Edit. It appears I was wrong. I just assumed that since my buddies truck has the 6.0 and it doesn't have the AFM or the indicator for it that none of them had it. His truck is a 2500 though. I just assumed it was the same motor. Also, my father's 09 didn't have the v4 indicator but did have AFM. Is it only if you had the 4 button dic?
 
#15 ·
Not without hands on the truck, I would call the dealer who worked on it last there should be some type of warranty on their repairs. Here are the parameters that must be meet before AFM can operate, any one not being meet will keep it off.

Manifold absolute pressure (MAP) and the conditions listed below determine when cylinder deactivation is enabled.

•Engine has been running for greater than 30 s
•Engine speed is between 700 and 2800rpm
•Engine oil pressure is between 187-455 kPa (27-66 psi)
•Engine coolant temperature is between 40-129°C (100-264°F)
•Engine oil temperature is between 16-128°C (61-263°F)
•Throttle angle is 6% or less
•Ignition voltage is greater than 11 V
•Transmission is not in first, second, or reverse gear
•Vehicle speed is greater than 25 kph (15.5 mph)
•Brake booster pressure is greater than 42.0 kPa (6 psi)
•Vehicle is not in fuel shut of mode
•Vehicle is not in heater performance mode
•Vehicle is not in tip in bump acceleration mode
•Vehicle is not in oil aeration mode
•Vehicle is not in low range (if equipped)
 
#16 ·
The 2500 cast iron block 6.0L (LY6, L96, LQ9, LQ4) has never had AFM. The only GM 6.0l engine that did was the L76 6.0 aluminum block, which was in GM SUVs and cars, never a pickup that I know of.
 
#19 ·
Scroll to the red font then tell me about it.

Service Information Home Publications Number Search New Bulletins Bulletin Search Feedback Help

2008 Chevrolet Silverado - 2WD | Sierra, Silverado VIN C/K Service Manual | Engine | Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L | Specifications | Document ID: 2041739
--------------------------------------------------------------------------------

Engine Mechanical Specifications (RPO LY6 VIN K)
Engine Mechanical Specifications Application
Specification

Metric
English

General

•Engine Type
V8

•Displacement
6.0L
364 CID

•RPO
LY6

•VIN
K

•Bore
101.618-101.636 mm
4.0007-4.0017 in

•Stroke
92.0 mm
3.622 in

•Compression Ratio
9.67:1

•Firing Order
1-8-7-2-6-5-4-3

•Spark Plug Gap
1.02 mm
0.04 in

Block

•Camshaft Bearing Bore 1 and 5 Diameter
59.58-59.63 mm
2.345-2.347 in

•Camshaft Bearing Bore 2 and 4 Diameter
59.08-59.13 mm
2.325-2.327 in

•Camshaft Bearing Bore 3 Diameter
58.58-58.63 mm
2.306-2.308 in

•Crankshaft Main Bearing Bore Diameter
69.871-69.889 mm
2.75-2.751 in

•Crankshaft Main Bearing Bore Out-of-Round
0.006 mm
0.0002 in

•Cylinder Bore Diameter
101.618-101.636 mm
4.0007-4.0017 in

•Cylinder Head Deck Height - Measuring from the Centerline of Crankshaft to the Deck Face
234.57-234.82 mm
9.235-9.245 in

•Cylinder Head Deck Surface Flatness - Measured Within a 152.4 mm (6.0 in) Area
0.11 mm
0.004 in

•Cylinder Head Deck Surface Flatness - Measuring the Overall Length of the Block Deck
0.22 mm
0.008 in

•Valve Lifter Bore Diameter
21.417-21.443 mm
0.843-0.844 in

Camshaft

•Camshaft End Play
0.025-0.305 mm
0.001-0.012 in

•Camshaft Journal Diameter
54.99-55.04 mm
2.164-2.166 in

•Camshaft Bearing Diameter
55.063-55.088 mm
2.1678-2.1688 in

•Camshaft Journal-to-Bearing Clearance
0.023-0.098 mm
0.0009-0.0038 in

•Camshaft Journal Out-of-Round
0.025 mm
0.001 in

•Camshaft Lobe Lift - Exhaust
7.13 mm
0.281 in

•Camshaft Lobe Lift - Intake
6.96 mm
0.274 in

•Camshaft Runout - Measured at the Intermediate Journals
0.05 mm
0.002 in

Camshaft Position Actuator

•Range of Authority
52 degrees

•Park Position
7 degrees Advanced

Connecting Rod

•Connecting Rod Bearing Clearance - Production
0.023-0.065 mm
0.0009-0.0025 in

•Connecting Rod Bearing Clearance - Service
0.023-0.076 mm
0.0009-0.003 in

•Connecting Rod Bore Diameter - Bearing End
56.505-56.525 mm
2.224-2.225 in

•Connecting Rod Bore Out-of-Round - Bearing End - Production
0.004-0.008 mm
0.00015-0.0003 in

•Connecting Rod Bore Out-of-Round - Bearing End - Service
0.004-0.008 mm
0.00015-0.0003 in

•Connecting Rod Side Clearance
0.11-0.51 mm
0.00433-0.02 in

Crankshaft

•Connecting Rod Journal Diameter - Production
53.318-53.338 mm
2.0991-2.0999 in

•Connecting Rod Journal Diameter - Service
53.308 mm
2.0987 in

•Connecting Rod Journal Out-of-Round - Production
0.005 mm
0.0002 in

•Connecting Rod Journal Out-of-Round - Service
0.01 mm
0.0004 in

•Connecting Rod Journal Taper - Maximum for 1/2 of Journal Length - Production
0.005 mm
0.0002 in

•Connecting Rod Journal Taper - Maximum for 1/2 of Journal Length - Service
0.02 mm
0.00078 in

•Crankshaft End Play
0.04-0.2 mm
0.0015-0.0078 in

•Crankshaft Main Bearing Clearance - Production
0.02-0.052 mm
0.0008-0.0021 in

•Crankshaft Main Bearing Clearance - Service
0.02-0.065 mm
0.0008-0.0025 in

•Crankshaft Main Journal Diameter - Production
64.992-65.008 mm
2.558-2.559 in

•Crankshaft Main Journal Diameter - Service
64.992 mm
2.558 in

•Crankshaft Main Journal Out-of-Round - Production
0.003 mm
0.000118 in

•Crankshaft Main Journal Out-of-Round - Service
0.008 mm
0.0003 in

•Crankshaft Main Journal Taper - Production
0.01 mm
0.0004 in

•Crankshaft Main Journal Taper - Service
0.02 mm
0.00078 in

•Crankshaft Rear Flange Runout
0.05 mm
0.002 in

•Crankshaft Reluctor Ring Runout - Measured 1.0 mm (0.04 in) Below Tooth Diameter
0.7 mm
0.028 in

•Crankshaft Thrust Surface - Production
26.14-26.22 mm
1.029-1.0315 in

•Crankshaft Thrust Surface - Service
26.22 mm
1.0315 in

•Crankshaft Thrust Surface Runout
0.025 mm
0.001 in

Cylinder Head

•Cylinder Head Height/Thickness - Measured from the Cylinder Head Deck to the Valve Rocker Arm Cover Seal Surface
120.2 mm
4.732 in

•Surface Flatness - Block Deck - Measured Within a 152.4 mm (6.0 in) Area
0.08 mm
0.003 in

•Surface Flatness - Block Deck - Measuring the Overall Length of the Cylinder Head
0.1 mm
0.004 in

•Surface Flatness - Exhaust Manifold Deck
0.13 mm
0.005 in

•Surface Flatness - Intake Manifold Deck
0.08 mm
0.0031 in

•Valve Guide Installed Height - Measured from the Spring Seat Surface to the Top of the Guide
17.32 mm
0.682 in

Intake Manifold

•Surface Flatness - Measured at Gasket Sealing Surfaces and Measured Within a 200 mm (7.87 in) Area that Includes 2 Runner Port Openings
0.3 mm
0.118 in

Lubrication System

•Oil Capacity - with Filter
5.68 liters
6.0 quarts

•Oil Capacity - without Filter
5.20 liters
5.5 quarts

•Oil Pressure - Minimum - Hot
152 kPa at 1,000 engine RPM

207 kPa at 2,000 engine RPM

228 kPa at 3,000 engine RPM
22 psig at 1,000 engine RPM

30 psig at 2,000 engine RPM

33 psig at 3,000 engine RPM

•Active Fuel Management Relief Valve Oil Pressure - as Measured at Oil Pressure Sensor Location
379-517 kPa

Maximum
55-75 psig

Maximum

Oil Pan

•Front Cover Alignment - at Oil Pan Surface
0.0-0.5 mm
0.0-0.02 in

•Crankshaft Rear Oil Seal Housing Alignment - at Oil Pan Surface
0.0-0.5 mm
0.0-0.02 in

•Oil Pan Alignment - to Rear of Engine Block at Transmission Bell Housing Mounting Surface
0.0-0.1 mm
0.0-0.004 in

Piston Rings

•Piston Ring End Gap - First Compression Ring - Measured in Cylinder Bore - Production
0.20-0.41 mm
0.0079-0.0161 in

•Piston Ring End Gap - First Compression Ring - Measured in Cylinder Bore - Service
0.20-0.46 mm
0.0079-0.0181 in

•Piston Ring End Gap - Second Compression Ring - Measured in Cylinder Bore - Production
0.37-0.69 mm
0.0146-0.0272 in

•Piston Ring End Gap - Second Compression Ring - Measured in Cylinder Bore - Service
0.37-0.75 mm
0.0146-0.0295 in

•Piston Ring End Gap - Oil Control Ring - Measured in Cylinder Bore - Production
0.22-0.79 mm
0.0086-0.0311 in

•Piston Ring End Gap - Oil Control Ring - Measured in Cylinder Bore - Service
0.22-0.84 mm
0.0086-0.0331 in

•Piston Ring-to-Groove Clearance - First Compression Ring - Production
0.04-0.083 mm
0.0016-0.0033 in

•Piston Ring-to-Groove Clearance - First Compression Ring - Service
0.04-0.083 mm
0.0016-0.0033 in

•Piston Ring-to-Groove Clearance - Second Compression Ring - Production
0.035-0.078 mm
0.0014-0.0031 in

•Piston Ring-to-Groove Clearance - Second Compression Ring - Service
0.035-0.078 mm
0.0014-0.0031 in

•Piston Ring-to-Groove Clearance - Oil Control Ring - Production
0.013-0.201 mm
0.0005-0.0079 in

•Piston Ring-to-Groove Clearance - Oil Control Ring - Service
0.013-0.201 mm
0.0005-0.0079 in

Pistons and Pins

•Pin - Piston Pin Clearance-to-Piston Pin Bore - Production
0.002-0.01 mm
0.00008-0.0004 in

•Pin - Piston Pin Clearance-to-Piston Pin Bore - Service
0.002-0.015 mm
0.00008-0.0006 in

•Pin - Piston Pin Diameter
23.952-23.955 mm
0.9430-0.9431 in

•Pin - Piston Pin Fit in Connecting Rod Bore - Production
0.007-0.02 mm
0.00027-0.00078 in

•Pin - Piston Pin Fit in Connecting Rod Bore - Service
0.007-0.022 mm
0.00027-0.00086 in

•Piston - Piston Diameter - Measured Over Skirt Coating
101.615-101.649 mm
4.0006-4.0019 in

•Piston - Piston-to-Bore Clearance - Production
−0.031 to +0.021 mm
−0.0012 to +0.0008 in

•Piston - Piston-to-Bore Clearance - Service Limit with Skirt Coating Worn Off
0.071 mm
0.0028 in

Valve System

•Valves - Valve Face Angle
45 degrees

•Valves - Valve Face Width
1.25 mm
0.05 in

•Valves - Valve Lash
Net Lash - No Adjustment

•Valve Lift - Exhaust
12.12 mm
0.477 in

•Valve Lift - Intake
11.83 mm
0.466 in

•Valves - Valve Seat Angle
46 degrees

•Valves - Valve Seat Runout
0.05 mm
0.002 in

•Valves - Valve Seat Width - Exhaust
1.78 mm
0.07 in

•Valves - Valve Seat Width - Intake
1.02 mm
0.04 in

•Valves - Valve Stem Diameter - Production
7.955-7.976 mm
0.313-0.314 in

•Valves - Valve Stem Diameter - Service
7.95 mm
0.313 in

•Valves - Valve Stem-to-Guide Clearance - Production - Exhaust
0.025-0.066 mm
0.001-0.0026 in

•Valves - Valve Stem-to-Guide Clearance - Service - Exhaust
0.093 mm
0.0037 in

•Valves - Valve Stem-to-Guide Clearance - Production - Intake
0.025-0.066 mm
0.001-0.0026 in

•Valves - Valve Stem-to-Guide Clearance - Service - Intake
0.093 mm
0.0037 in

•Valves - Valve Stem Height - Measured from Spring Seat - Intake and Exhaust
50.85 +/− 0.375 mm
2.00 +/− 0.015 in

•Rocker Arms - Valve Rocker Arm Ratio
1.70:1

•Valve Springs - Valve Spring Free Length
52.9 mm
2.08 in

•Valve Springs - Valve Spring Installed Height
45.75 mm
1.8 in

•Valve Springs - Valve Spring Load - Closed
340 N at 45.75 mm
76 lb at 1.8 in

•Valve Springs - Valve Spring Load - Open
980 N at 33.55 mm
220 lb at 1.32 in

© 2014 General Motors. All rights reserved.
 
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