An engine surge is usually caused by a fuel system management or drive train operation failure. The fuel management system utilizes sensors that monitor emission output and engine performance and are communicating with the main PCM (power train control module) controlling fuel mixture, timing and emission management systems. While the engine is surging the PCM is "hunting" by adjusting the fuel mixture and timing. These adjustments are made by the PCM in an isolating manner as the PCM tries to satisfy its parameters. These parameters are not being satisfied due to a system malfunction. Below are the listed most common problems and repairs:
Car Repair Troubleshooting Guide
Step 1 - Test for DTS's (Diagnostic Trouble Codes): For this you need a trouble code scanner. The trouble code scanner is a small hand held electronic device that plugs into the vehicle's OB2 (OBD11) diagnostic connector. Locate the vehicle's computer connector (ALDL), most are on the lower driver's side. In some vehicles you might need to look around a little, on the passenger's side, and around the center console under a plastic cover. For more information, check the vehicle's owner's manual. This device gathers information that was stored in the vehicle's PCM. This information or trouble code can inform you about the system or sensor that is malfunctioning. Look up the code in our diagnostic trouble code chart. After repairs have been made use the code scanner to clear trouble codes and
recheck system. Check Engine Light Service Engine Soon Video
Step 2 - Testing Fuel Pressure: Test for proper fuel pressure with a fuel pressure
gauge. Connect the gauge to the test port on the fuel rail. Fuel pressure reading's varies depending on the system for the vehicle, most throttle body injection cars (TBI) are between 13 psi and 17 psi and most (DPI) direct port inject systems are between 40 psi and 55 psi. To find out the vehicle's system fuel pressure consult a car repair manual. If fuel pressure is not within specification the fuel pump needs to be replace.
Step 3 - Plugged Fuel Filter: A plugged fuel filter can cause an engine to surge. Proper fuel system pressure is critical to fuel injected engines, other wise there will be inconsistencies in performance. To check for this condition remove the fuel filter and inspect, replace with new unit and recheck system. Fuel Filter Removal
Step 4 - Check Engine for Vacuum Leaks: If an engine vacuum leak is present it will cause the sensor input readings to the PCM to be incorrect resulting in an
engine surge. The system is programmed to work at a predetermined value. When a vacuum leak is present these readings are incorrect causing the engine to surge under power and idle rough. Inspect the air intake boot for tears and vacuum feed lines to all accessories. Replace torn or dilapidated hose with a new hose and recheck system. Also an IAC (Idle Air Control) valve bypass hose can develop tears/holes mid way through the hose, inspect thoroughly (common problem on Ford trucks and SUV's). Sometimes a vacuum leak can be detected by opening the hood, start the engine and allow to idle, listen for an audible
whistling sound. Inspect that area of the engine compartment to locate the leak.
Step 5 Check for Plugged Exhaust System: The exhaust system in your vehicle is designed to release exhaust gases from the engine to the rear of the car. This system is designed to have about 3 pounds of exhaust backpressure under full throttle. This means the engine should not have to push more than 3 pounds of
pressure to release the exhaust at any given time. If a catalytic converter plugs or breaks apart it will plug the exhaust system causing an engine surge.
Step 6 - Test for Weak Ignition Spark or Failing System: A weak ignition system can be a sign of a failing ignition component and can cause the engine to surge. Remove spark plug wire and insert an extra spark plug into end of wire, attach spark plug to engine ground then crank engine. You should observe blue spark between spark plug gap. If a yellow spark is observed, your ignition coil is weak and needs to be replaced. Also the spark should flash in a constant rhythm, if the spark is inconsistent suspect the crank angle senor, ignition coil or ignition module.
Step 7 - Check for Automatic Transmission Clutch Slippage: When the clutches inside an automatic transmission start to wear they can malfunction. This condition will deliver a surging or a tugging sensation to the driver. Without taking the transmission apart it is impossible to check the wear of the clutch discs. But there are tests that can help you in the diagnosis. First remove transmission dip stick and inspect the condition of the fluid; if the
fluid has a burnt smell and is dark color instead of the normal red color the fluid is burnt. (The transmission fluid is a hydraulic fluid that when extreme heat is applied to the fluid it becomes dark in color and will smell burnt). The extreme heat is generated from the clutch discs slipping. Sometimes a transmission service will help the operation by removing the burnt fluid and replacing it with new
Step 8 - Check for Standard Transmission Clutch Slippage: When a clutch assembly starts to wear it can cause an engine surge sensation. This is caused by the clutch pressure plate loosing tension and allowing the clutch disc to slip against the flywheel. The clutch assembly is a normal service item and will need to be inspected between 70,000 and 120,000 miles. If the clutch pedal is at the top of its travel with no free-play this is a sign the clutch assembly is worn out and needs replacing. When servicing a clutch disc always replace the clutch disk, pressure plate, throw out and pilot bearings, also have the flywheel surfaced to ensure a good surface for disc contact (Note: some transmissions do not use a
pilot bearing). The flywheel is the component the clutch assembly bolts to, the clutch disc is in direct contact with the flywheel and clutch pressure plate.
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