How to Fix a Engine RPM Up and Down?

Model: Hyundai Grandeur

Year Model: 2001

Displacement: 3000cc

Fuel : Gasoline

T/A : Auto

Subject: RPM Up and Down on Stop Light When the Engine is in Hot Condition.

1) Condition

1. RPM Up and Down on Stop Light When The Engine is in Hot Condition.
2. Cut on Engine Idling.

2) Cause

1. Due to the EGR hose leaking.
2. Failure sensor malfunctioning.

3) Diagnosis

1. Check Scan tool
   =Trouble Code (P1191 & P1193 = Related on Throttle Body)
   In relation to the trouble code.
   1) Ignition system.
   2) Fuel System.
   3) Air leaking.
   4) Poor contact of socket pin and terminals.
2. Check by road testing to confirm the problem = Confirmed
3. Check the Spark plug and High tension wire = OK
4. Check for fuel pressure with Gauge = OK
5. Check and repair vacuum hose from EGR = OK
6. Clean all wiring terminal from engine = Ok
   = Test again but the problem still occurs.
7. Check for current data
   = Engine RPM very low reading.
   = Air and Fuel mixture out of Specification.
8. Check for wiring diagram of MFI.
   = failure sensor is connected to the tachometer.
   Check the terminal wiring = current OK
9. Check with good failure sensor and Adjust the RPM to the TPS and Acceleration position sensor. then road test = the problem disappear.

4) Repair Guides

Replace Failure sensor.

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