Filed Under (Jeep) by admin on 18-11-2010
1. Disconnect vacuum hose at speed control servo and install a vacuum gauge into the disconnected hose. 2. Start engine and observe gauge at idle. Vacuum gauge should read at least ten inches of mercury. 3. If vacuum is less than ten inches of mercury, determine source of leak. Check vacuum line to engine for leaks. Also check actual engine intake manifold vacuum. If manifold vacuum does not meet this requirement, check for poor engine performance and repair as necessary. 4. If vacuum line to engine is not leaking, check for leak at vacuum reservoir. To locate and gain access to reservoir, refer to Vacuum Reservoir REMOVAL /INSTALLATION . Disconnect vacuum line at reservoir and connect a hand-operated vacuum pump to reservoir fitting. Apply vacuum. Reservoir vacuum should not bleed off. If vacuum is being lost, replace reservoir. 5. Verify operation of one-way check valve and check it for leaks. a. Locate one-way check valve. The valve is located in vacuum line between vacuum reservoir and engine vacuum source. Disconnect vacuum hoses (lines) at each end of valve. b. Connect a hand-operated vacuum pump to reservoir end of check valve. Apply vacuum. Vacuum should not bleed off. If vacuum is being lost, replace one-way check valve. c. Connect a hand-operated vacuum pump to vacuum source end of check valve. Apply vacuum. Vacuum should flow through valve. If vacuum is not flowing, replace one-way check valve. Seal the fitting at opposite end of valve with a finger and apply vacuum. If vacuum will not hold, diaphragm within check valve has ruptured. Replace valve.
Filed Under (Saturn) by admin on 04-06-2010
Condition Some customers may comment on the (MIL) SERVICE ENGINE SOON telltale being illuminated. (DTC(s) P0171 – Fuel Trim System Lean Bank 1 and/or DTC P0174 – Fuel Trim System Lean Bank 2 may be set and stored in the ECM memory.) Cause This condition may be caused by insufficient torque on the intake manifold vacuum chamber bolts. Under deceleration, enough vacuum can be created inside the intake manifold to lift the vacuum chamber off it’s seal creating an intermittent vacuum leak. Correction Refer to the service procedure in this bulletin to retorque the intake manifold vacuum chamber bolts and install the vacuum chamber springs. Procedure: Notice: When servicing intake manifold, do not use power tools. Damage to threads or manifold may occur. 1. Loosen clamp at air cleaner assembly and throttle body assembly. 2. Remove attachment bolts from outlet resonator/duct assembly.
Filed Under (Chevrolet) by admin on 11-08-2010
Subject: Engagement Time of Electronically Controlled Transmissions in General Motors Vehicles (Garage Shins, Park to Reverse, Neutral to Drive, Neutral to Reverse, Park to Drive, Delayed Engagement) Models: 2000-2002 Chevrolet Cámaro 2000-2005 Chevrolet Corvette 2000-2002 Pontiac Firebird 2004-2006 Pontiac GTO 2000-2007 All GM Light Duty Trucks 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X with 4L60-E (RPO M30) or 4L65-E (RPO M32) Automatic Transmission Supercede: This bulletin is being revised to remove 2006-2007 Chevrolet Corvettes. Please discard Corporate Bulletin Number 03-07-30-007C (Section 07 – Transmission/Transaxle). Park/Neutral to Reverse or Drive (commonly called garage shift) engagement times may be different from what many customers might be accustomed to especially if they have recently traded for a General Motors vehicle. Normal Park/Neutral to Reverse or Drive engagement time will be in the vicinity of one (1) second if the automatic transmission fluid (ATF) is above 0°C (32°F) . When the ATF is colder than 0°C (32°F), the engagement time will become longer the colder the transmission fluid. A time limit factor cannot be placed on proper engagement times because the factors that affect transmission operation are many. At the moment of engine start, for economy and emission requirements, the transmission line pressure is maintained at low levels. This allows a lower cold idle engine RPM (the colder the oil is the higher the energy level (engine torque output) required to pressurize the oil).
Filed Under (Chevrolet) by admin on 19-10-2010
1. Disconnect the brake booster vacuum check valve (1) from the brake booster. 2. If the vacuum check valve (1) needs to be separated from the vacuum hose (3), release and reposition the clamp (2) on the vacuum hose (3) and remove the check valve (1) from the hose (3). 3. If replacing the vacuum check valve (1), remove the grommet (4) from the brake booster and discard the grommet. 4. If removing the vacuum hose (2), take note of the vacuum hose routing then disconnect from the engine intake manifold connection (3) by releasing tension on the vacuum hose clamp (1) and sliding the vacuum hose (2) off the intake manifold connection (3). Installation Procedure Important: A small amount of denatured alcohol can be used as an assembly aid when installing the vacuum check valve and/or grommet. Do NOT use soap. 1. If the vacuum hose (2) was removed, install the vacuum hose into position on the vehicle as noted prior to removal, then connect the vacuum hose (2) to the engine intake manifold connection (3) and secure with the vacuum hose clamp (1). 2. If the vacuum check valve (1) is being replaced, install a NEW grommet (4) to the brake booster. 3. If the vacuum check valve (1) was separated from the vacuum hose (3), install the check valve (1) to the vacuum hose (3). Install and secure the clamp (2) into position on the hose (3). 4. Connect the brake booster vacuum check valve (1) to the brake booster.
Filed Under (Chevrolet) by admin on 03-09-2010
Subject: Audible Spark Knock (Detonation), MIL Illuminated, DTC P0332 Set (Replace Rear Bank Knock Sensor and RTV Area Around Sensor) Models: 1998-2002 Chevrolet Camaro, Corvette 1998-2002 Pontiac Firebird with 5.7L Engine (VIN G – RPO LS1) 1999-2002 Chevrolet Silverado, Suburban, Tahoe 2002 Chevrolet Avalance 1999-2002 GMC Sierra, Yukon, Yukon XL 2002 Cadillac Escalade, Escalade EXT with 4.8L, 5.3L or 6.0L Engine (VINs V, T, Z, N, U – RPOS LR4, LM7, L59, L09, L04) This bulletin is being revised to add Cadillac Escalade and Cadillac Escalade EXT to the Models. Please discard Corporate Bulletin Number 02-06-04-023 (Section 6 – Engine/Propulsion System). Condition Some customers may comment on a mild to severe engine ping (commonly referred to as spark knock), usually worse during acceleration and/or an illuminated MIL. Upon investigation, the technician may find DTC P0332 set. Cause This condition may be the result of corrosion of the rear bank knock sensor due to water intrusion into the sensor cavity. This condition is more apparent on vehicles in which customers frequently wash the engine compartment