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GMC Engine Problems

Why does a GMC engine have starting problems in cold weather? Why is a GMC engine running rough? What causes low gas mileage on GMC engines? What is the best way to diagnose GMC engine problems?

When faced with these and other questions, vehicle owners will find that the answers and guidance of Experts will enable them to get the right repairs done.

Read below where Experts have answered questions pertaining to the GMC engine.

What could cause a GMC engine to start with starting fluid in cold weather but now when starting is it only knocks but will not start?

It appears that the engine “ran away.” This happens when starting fluid accumulates in the intercooler and hoses and when the engine starts the excess fluid causes the engine to over speed because the fuel was not from a metered and controlled source. The fact that it is not starting after that happened and that the engine knocks indicates that it is likely that the pistons have been damaged. A compression test will reveal which of the cylinders have low pressure. Any cylinders that show low pressure will have either piston or valve damage and since this was caused by over speed, the pistons are most likely to be the cause.

What do the following codes mean on a 1998 GMC Sierra 1500 – P0154, P0155 and P1153.

The codes cited point to a faulty oxygen sensor – bank 2 sensor 1. This is the one on the passenger side of the engine before the catalytic converter. Driving the vehicle with the defect will affect the gas mileage. A new oxygen sensor may cost about $100.

The Service Engine light is flashing n a GMC Sierra. Does this mean there is a serious GMC engine problem? What is the solution?

When the service engine light flashes it indicates that the computer has found an engine misfire. This can cause damage to the catalytic converter if it continues for any length of time. The cause is typically a defective spark plug, plug wire or ignition coil. A restricted fuel injector and low compression in 1 or more cylinders can also cause this condition. The solution lies in taking the vehicle to a shop that has the appropriate scan tool to diagnose which of the cylinder is misfiring. Once this is done, the cause of the misfire can be located and corrective action taken.

How to remove the oil lines between the GMC engine and the radiator on a 2006 Yukon Denali with a 6 liter engine?

The procedure for removing the hoses is as follows:
• Remove the clips from the engine coolant lines on the radiator.
• From under the engine, remove the skid plate.
• Next some bolts on the front differential will need to be removed to allow it to drop down to 3 inches. Loosen the bolt under the back yoke; remove the long bolts on the top and also the two bolts on the passenger side axle tube.
• Push the axle tube down and remove the front drive shaft.
• The differential assembly should be down a few inches and be resting against the steering shaft.
• Locate the 2 bolts on the side of the engine where the cooler line assembly is attached to the engine block. Remove these bolts and any other clips that may be in place.
• Now the hose at the front and bottom can be removed. It may take some effort to work the block past the front differential but is can be done.

Why is the P0506 GMC engine code showing on a 2006 Envoy SLT?

The P0506 is often triggered on GMC engines equipped with electronic throttle control. These vehicles do not have the normal throttle cable running from the accelerator pedal to the engine but use sensors and electronic to control engine speed. The P0506 DTC (Diagnostic Trouble Code) appears when the Powertrain Control Module detects that the engine is idling at lower than the required speed. A DTC is an informational code so if any other codes are set, these will need to be diagnosed first to see where the problem lies.

Diagnosing GMC engine problems can be a complex affair. The wrong diagnosis and repair can make a problem worse than it is and add to repair costs. It is best if vehicle owners have reliable information available to allow them to make the right repair choices. The insights and opinions of Experts is an invaluable resource in such cases.
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