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I recently replaced my PCV valve and noticed that the old one is a 'fixed oriface' type and the new one (a Fram FV391) is a spring/plunger type. With the new one, the truck seems to idle more smoothly and about 50 rpm higher than before. Am I imagining this or could the new valve really make the difference.

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You shouldnt change from the fixed orfice PCV unless you want more #1 oil consumption #2 dirty throttle body and requiring cleaning to stopping sticking. 2004 & up have permanent fixed orfice.

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Read this..........

 

Document ID# 901494

2001 Chevrolet Chevy K Silverado - 4WD

 

 

--------------------------------------------------------------------------------

 

 

Subject: Higher Than Expected Engine Oil Consumption (Replace PCV Valve) #01-06-01-029B - (07/19/2002)

 

 

 

Models: 2002 Chevrolet Avalanche

 

1999-2002 Chevrolet Silverado, Suburban, Tahoe Models

 

2002 Cadillac Escalade, Escalade EXT

 

1999-2002 GMC Denali, Sierra, Suburban, Yukon Models

 

with 4.8L, 5.3L or 6.0L Engine (VINs V, T, N, U -- RPOs LR4, LM7, LQ9, LQ4)

 

 

 

 

--------------------------------------------------------------------------------

 

This bulletin is being revised to clarify the parts information. Please discard Corporate Bulletin Number 01-06-01-029A (Section 06 -- Engine/Propulsion System).

 

 

--------------------------------------------------------------------------------

 

Condition

Some customers may comment on higher than expected engine oil consumption. They may further comment on consumption in the range of 3,200 km (2,000 mi) or less per quart (0.946 liter) of oil under normal driving conditions.

 

Cause

The condition may be due to the positive crankcase ventilation (PCV) valve flow rate under certain engine operating conditions.

 

Correction

Verify that the oil consumption is not the result of an oil leak or other engine concern.

The dealer should perform an oil consumption test. The vehicle should have accumulated over 6,450 km (4,000 mi) before establishing the oil consumption rate. Reference Corporate Bulletin Number 01-06-01-011, Information on Engine Oil Consumption Guideline, for details.

Remove the PCV valve and inspect the hose going to the intake manifold for signs of excessive oil being present.

If excessive oil is present in the PCV hose, replace the PCV valve (Type 948C) (2) with a new-style fixed orifice PCV valve, GM P/N 12572717(1). See the illustration below.

PCV Valve Identification

 

 

 

 

(1) New style fixed orifice PCV Valve

(2) Spring and plunger style PCV Valve (Type 948-C)

 

Important: The new style fixed orifice PCV valve contains no moving parts, and does not rattle when shaken.

 

If the vehicle has an orifice style PCV valve, investigate other causes for high oil consumption.

 

Parts Information

Part Number

Description

Qty

 

12572717

Valve, PCV

1

 

 

Parts are currently available from GMSPO.

 

Warranty Information

For vehicles repaired under warranty, use:

 

Labor Operation

Description

Labor Time

 

J6000

Valve, PCV - Replace

Use published labor operation time

 

 

 

 

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

 

 

© Copyright General Motors Corporation. All Rights Reserved.

 

 

--------------------------------------------------------------------------------

Document ID# 901494

2001 Chevrolet Chevy K Silverado - 4WD

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I agree with redvett,I wouldn't change from the fixed to the non-fixed orifice PCV Valve.

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I changed from the spring/plunger to the fixed orifice type to fix my oil burning problem 5k miles and all oil burning it gone.

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That's all great information but can someone answer my question?

 

 

 

I would say you are imagining the increased RPM and smoothness. Like a placebo effect when they test new drugs.

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Thanks, I'm gonna leave it in for a while and check for oil consumption. I don't know why all of the 'parts store replacements' are the plunger type and the factory piece is fixed. But I'll test it out for a while.

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The factory PCV was changed to fix throttle sticking & oil consumption. Changing isnt reccomended. Higher idle = more fuel consumption.

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Thanks, that's a good article. I'll probably change it back after a while but I want to see what happens with the plunger type. I'll be cleaning the throttle body shortly anyway when I change the coolant and hoses. By the way, I have the electronic throttle control so how would I know it I have a 'sticky' throttle?

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The bulletin covers '99 to '02 trucks with the "cable" throttle body,not the electronic throttle control.

But you should still use the fixed orifice PCV Valve.

Heres the bulletin thats mentioned in the article.....

 

 

 

Document ID# 1269746

 

--------------------------------------------------------------------------------

 

 

Subject: Increased Accelerator Pedal Effort, Idle Instability (Clean Throttle Body and Adjust Blade) #02-06-04-054B - (03/17/2003)

 

 

 

Models: 1999-2002 Chevrolet Silverado

 

2000-2002 Chevrolet Suburban, Tahoe

 

2002 Chevrolet Avalanche

 

1999-2002 GMC Sierra

 

2000-2002 GMC Yukon, Yukon XL

 

with 4.8L or 5.3L V8 Engine (VINs V, T, Z -- RPOs LR4, LM7, L59)

 

 

 

 

--------------------------------------------------------------------------------

 

This bulletin is being revised to add condition information. Please discard Corporate Bulletin Number 02-06-04-054A (Section 06-Engine).

 

 

--------------------------------------------------------------------------------

 

Condition

Some customers may comment on an idle instability and/or a higher than expected accelerator pedal effort from the idle position.

 

Cause

Condition may be caused by deposits in the throttle body bore and on the throttle plate.

 

Correction

Important: This procedure only applies to cable actuated throttle bodies on the models listed above. This procedure should not be performed on electronically controlled throttle bodies or on any vehicle or engine that is not listed above in the Models section.

 

Verify that the cause for this condition is not a damaged or binding throttle cable.

Remove the air intake duct. Refer to Air Cleaner Duct Replacement.

Inspect the vehicle for installation of a fixed orifice PCV valve, refer to Corporate Bulletin Number 01-06-01-029B for PCV valve identification. Vehicles undergoing this throttle body procedure MUST use a Fixed Orifice PCV Valve, P/N 12572717.

Clean throttle body bore and throttle valve plate of carbon using a shop rag and an appropriate cleaner. Refer to Engine Controls Repair Procedures - Throttle Body Cleaning Procedure.

Select the correct plug for the size of the air bypass hole in the throttle body being serviced. Use a 1/8-inch (.125") drill bit to determine which plug to use.

• Vehicles built before introduction of the Fixed Orifice PCV Valve will have a 3.75 mm (.150") air bypass hole in the throttle plate. The 1/8-inch drill bit is smaller than the air bypass hole in these throttle bodies and can be inserted into the bypass hole. To plug the air bypass hole in these vehicles requires the yellow plug, P/N 12580749.

 

• Vehicles built after introduction of the Fixed Orifice PCV Valve will have a 2.6 mm (.104") air bypass hole in the throttle plate. The 1/8-inch drill bit is larger than the air bypass hole in these throttle bodies and cannot be inserted into the bypass hole. To plug the air bypass hole in these vehicles requires the red plug, P/N 12581011.

 

 

 

 

 

Insert the appropriate plug (1) into the air bypass hole in the throttle plate. Insert the "tail" end of the plug through the throttle plate air bypass hole.

 

 

 

Open the throttle plate to allow access to the tail end of the plug. Pull the tail section to securely position the plug into the air bypass hole and trim excess material (1) from plug.

Turn ignition key to the on position, with engine off.

Use the Tech 2 Scan tool to read initial TPS voltage.

Important: TPS voltage cannot exceed .69 V. If the vehicle has an initial TPS voltage greater than .61 V, replace the Throttle Body Assembly. This part is currently on parts restriction. Contact the General Motors Powertrain Quality Center for assistance.

 

Using the Tech 2 Scan tool and a T15 driver to rotate the Minimum Air Rate screw, increase TPS voltage by .08 Volts (Refer to TPS Voltage Chart below).

Turn ignition key to the off position. Verify that the accelerator pedal moves freely - Depress the accelerator pedal to the floor and release.

Install the air intake duct. Refer to Air Cleaner Duct Replacement.

Start engine.

Using the Tech 2 scan tool, monitor TPS voltage and verify the TPS voltage is no greater than 0.69V.

Road Test Vehicle.

Important: If an increased accelerator pedal effort condition still exists after performing this bulletin, throttle body replacement may be required. Please contact the General Motors Powertrain Quality Center for assistance, as the throttle body is currently on a parts restriction program.

 

 

 

TPS Voltage Chart Initial TPS Voltage

TPS Voltage After .08 Volt Increase

 

0.45 V

0.53 V

 

0.47 V

0.55 V

 

0.49 V

0.57 V

 

0.51V

0.59 V

 

0.53 V

0.61 V

 

0.55 V

0.63 V

 

0.57 V

0.65 V

 

0.59 V

0.67 V

 

0.61 V

0.69 V

 

 

If initial TPS voltage is greater than .61 V Replace Throttle Body Assembly

 

Parts Information

Part Number

Description

Qty

 

12580749

Plug, Throttle Plate - Yellow

1

 

12581011

Plug, Throttle Plate - Red

1

 

 

Parts are currently available from GMSPO.

 

Warranty Information

For vehicles repaired under warranty, use:

 

Labor Operation

Description

Labor Time

 

J5984

Throttle Body - Clean and Adjust

0.6 hr

 

 

 

 

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

 

 

© Copyright General Motors Corporation. All Rights Reserved.

 

 

--------------------------------------------------------------------------------

Document ID# 1269746

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I seem to be experiencing some oil comsumption lately and have occassionally had the sticking throttle (cleaning trottle body has kinda become regular maintenence). The last time I cleaned my trottle body there was a small pool of oil at the plate.

As posted above, if I was to switch my PVC from the spring/plunger to the fixed type, would I also have to up the TPS voltage (don't have a scan tool)?

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NO,You only turn-up the voltage if you plug the hole in the throttle plate and perform the bulletin I posted above,If you just change the PCV Valve to the "fixed-orifice" PCV valve you don't turn-up the voltage.

 

Remember you must have the "fixed-orifice" PCV valve first before you perform the bulletin for the sticking throttle pedal.

 

Trust me,Get this bulletin done on your truck if your throttle pedal is sticking,When I had my '99 I was constantly cleaning the throttle body every 8 to 10,000 miles,after I performed the bulletin I was good to go!

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Does the fixed orifice style require replacing at the same intervals as a normal PCV valve? I noticed the manual and reference books at auto parts store list say the valve is a non-replaceable part on my 2004. No part number is listed in those books.

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