Can the Flex fuel sensor cause SUV to run badly

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As far as oil pressure, this component will not have an affect. It is an exclusive sensor specific to the recognition of fuel type being used.

The flex fuel sensor measures the ethanol-gasoline ratio of the fuel being used in a flexible fuel vehicle. Flexible fuel vehicles can be operated with a blend of ethanol and gasoline, up to 85 percent ethanol. In order to adjust the ignition timing and the fuel quantity to be injected, the engine management system requires information about the percentage of ethanol in the fuel.

All fuel passes through the fuel composition sensor before continuing on to the fuel rail. The fuel composition sensor measures two different fuel related parameters, and sends an electrical signal to the PowerPoint Control Module (PCM) to indicate ethanol percentage, and fuel temperature.

If the sensor is inaccurate, the engine running conditions will be affected because it will change ignition timing and the amount of fuel being injected into the engine. However, it should have set a diagnostic trouble code related to the sensor. (Check engine light)

I will provide the directions for replacement. All attached pictures correlate with the directions.

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2002 Chevy Truck C 1500 Suburban 2WD V8-5.3L VIN T
Procedures
Vehicle Powertrain Management Fuel Delivery and Air Induction Sensors and Switches - Fuel Delivery and Air Induction Flexible Fuel Sensor Service and Repair Procedures
PROCEDURES
FUEL COMPOSITION SENSOR REPLACEMENT

REMOVAL PROCEDURE

pic 1

1. Turn OFF the ignition.
2. Relieve the fuel pressure. Refer to Fuel Pressure Relief Procedure.
3. Raise the vehicle.
4. Remove the fuel composition sensor fuel composition sensor (FCS) attachment nuts (1).

Pic 2

5. Disconnect the FCS inlet and outlet pipes from the FCS.

Pic 3

6. Disconnect the FCS electrical connector (1).
7. Remove the FCS and bracket assembly from the frame rail.

Pic 4

8. Remove the FCS bolts and remove from the bracket.

INSTALLATION PROCEDURE

NOTE: Refer to Fastener Notice in Service Precautions.

Pic 5

1. Install the FCS to the bracket and install bolts.

Tighten
Tighten bolts to 10 N.M (89 lb in).

2. Install FCS and bracket assembly to frame.

Pic 6

3. Install FCS bracket to frame nuts.

Tighten
Tighten nuts (1) to 17 N.M (13 lb ft).

Pic 7

4. Connect the FCS inlet and outlet pipes to the FCS.

Pic 8

5. Connect the FCS electrical connector (1).
6. Lower the vehicle.
7. Start the engine and check for fuel leaks.

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Let me know if this helps or if you have other questions.

Take care,
Joe