2003 GMC Yukon Loss of Power

Tiny
BCMULLEN95
  • MEMBER
  • 2003 GMC YUKON
  • V8
  • 4WD
  • AUTOMATIC
  • 139,000 MILES
My Yukon has a loss of power when pressing the gass pedal to the floor, while passing someone on the freeway. The truck does not want to go faster than 20-25mph. It behaves as though the engine is flooded. Waiting about five minutes or so will allow the truck to go again whith out a loss of power. This only occurs after wide open throttle. The check engine light comes on and shows the code for mass air flow sensor. I have cleaned sensor and it resolve problem for a short time only. I have replace the fuel pump and am leaning towards cleaning the intake manifold, thottle body and injectors to see if this may be causing some of the problems. Is there a possiblity the fuel pump is malfunctioning?
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Saturday, October 2nd, 2010 AT 12:27 PM

4 Replies

Tiny
MERLIN2021
  • EXPERT
You could check the fuel pressure to check it, and you did say cleaning the MAF work for a while, do you have an oil soaked air filter like K & N? These are known to ruin MAF sensors, and Chevy voids warranties due to their use on MAF sensors. Unplug the MAF and test drive it, the computer will use a mid point value and the check engine light will come on during the test drive, but if the problem clears, replace the MAF, cleaning dosent always work. The other possibility is a clogged catalytic converter.
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Saturday, October 2nd, 2010 AT 12:49 PM
Tiny
BCMULLEN95
  • MEMBER
It has the factory intake with the exception of a tornado that is in the intake hose after the MAF sensor. My biggest problem is the loss of power after wide open throttle. Every time I step on the gas and floor the pedal to pass someone one the freeway, the truck acts as though it is flooded. I have even heard it backfire some. If you let it rest for a while it will begin to run fine with the exception of a check engine light that comes on. Is igt possible that the catalyic converter is too clogged to allow the proper exost flow therefore causing the engine to not properly conbust creating the flooded type condition. I have seen where many have this same problem yet can not figure out why. I will run it with the MAF diconnected to see if the condition continues. Thanks
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Saturday, October 2nd, 2010 AT 2:29 PM
Tiny
BCMULLEN95
  • MEMBER
I replaced the MAF. I am currently have the code P0171. I will be checking the fuel pressure and look for leaks. Is their anythig else that I can do or look for that might be causeing this code. The Yukon doesn't like to start on the first crank, it is usually the second or third crank. Is this a sign of a fuel pump going bad or leak somewhere where the gas is not staying. Do you know the specs for the gas pressure for a 03 Yukon XL 5.3L 4X4.
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Sunday, October 3rd, 2010 AT 12:44 AM
Tiny
MERLIN2021
  • EXPERT
System too lean bank 1
Is this a flex fuel vehicle? If so, replace the lower intake manifold gaskets. Here's the tsb, and even though you don't have a misfire code, the lean code is either an unmetered air leak, or weak fuel pump, but if the pump was the reason you should get a lean code on both banks. You can try spraying throttle body cleaner at the suspected area between the intake and the head and if the idle changes, there is a leak.
Flexible Fuel (RPO L59) Rough Idle, Misfire, MIL DTC P0300 (Install Intake Manifold Gaskets With Teal Green Gasket Material) TECHNICAL SERVICE BULLETIN Reference Number(s): 05-06-04-029A, Date of Issue: June 24, 2005 Related Ref Number(s): 05-06-04-029A ARTICLE BEGINNING SERVICE INFORMATION CONDITION Some customers may comment that the vehicle may have a rough idle, misfires and/or a MIL illuminated with a stored DTC P0300. CAUSE The L59 engine is calibrated for ethanol fuel (E85). Due to the low volatility of ethanol, the PCM provides higher fuel flow through the injector, which may pool on the upper manifold to head gasket material. Over time (usually 12 months and longer), the gasket material may degrade resulting in an unmetered air leak. CORRECTION Replace the upper intake manifold gaskets with the teal green gasket material, P/N 89017589. Press Ctrl+F to find exact text Affected Model(s): 2002-2004 Chevrolet Silverado, Suburban, Tahoe; 2002-2004 GMC Sierra, Yukon, Yukon XL; with 5.3L Engine and Flexible Fuel (VIN Z - RPO L59); This bulletin may apply to the following engines using regular fuel: 4.8L, 5.3L, 6.0L (VINs V, T, P, U, N - RPOs LR4, LM7, LM4, LQ4, LQ9). Supercedes: This bulletin is being revised to add additional diagnostic information. Please discard Corporate Bulletin Number 05-06-04-029 (Section 06 - Engine/Propulsion System). IMPORTANT: Always begin your diagnosis with the Diagnostic System Check - Engine Controls (SI Document ID #1289827) for any MIL or driveability concern. The Diagnostic System Check directs you to the next logical step in your diagnosis. Follow the instructions in this bulletin should the rough idle, misfire, or DTC P0300 diagnostic procedure point to an air leak in the intake manifold gasket. Following the published diagnostic procedures will improve diagnostic accuracy and support our fix it right the first time approach. IMPORTANT: Do not replace the upper intake manifold gaskets with the original orange gasket material, P/N 17113557. Inspect Intake Manifold to Cylinder head Deck for Warpage Fig. 1: Intake Manifold Courtesy of GENERAL MOTORS CORP. 1. Locate a straight edge across the intake manifold cylinder head deck surface. Position the straight edge across two runner port openings. 2. Insert a feeler gauge between the intake manifold and the straight edge. An intake manifold with warpage in excess of 3 mm (0.118 in) over a 200 mm (7.87 in) area is warped and should be replaced. Do not replace intake manifolds with warpage that measures less than 3 mm (0.118 in) over a 200 mm (7.87 in). PARTS INFORMATION Parts Information WARRANTY INFORMATION For vehicles repaired under warranty, use: Warranty Information Part Number Description 89017589 Gaskets, Upper Intake Manifold (Teal Green) Labor Operation Description Labor Time J 0251 Gasket, Intake Manifold - Replace Use Published Labor Operation Time
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Sunday, October 3rd, 2010 AT 2:00 AM

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