Poor Engine Acceleration and Hesitation

Model: Hyundai Grandeur (XG)

Displacement: 3000cc

Model Year: 2004

mileage: 120430 km

Fuel: Gasoline

T/A : All

1) Condition:

1. Poor engine acceleration and hesitation.

2) Cause:

1. Surge tank is misassembled after the spark plug are replaced which cause air leaking.

3) Diagnosis:

1. Scan tool check
   = Diagnosis Trouble Code(P0100 – Airflow sensor malfunction.
2. Current data shows the injection time from injector which is longer than spec. at idling(4ms).
3. AFS output signal is 1567 mV at ignition on. This data is higher than specification.
4. After changing the AFS, poor acceleration is disappeared, but there are still unstable engine and air leaking noise at idling.
5. Cleaning spray(WD 40) is sprayed toward surge tank for leaking test, Engine RPM is charged when spraying , which indicates air leakage.

4) Repair Guide

• Reinstall the surge tank and replace the AFS.

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