Engine - Rough Idle/MIL ON/DTC's P0171/P0301-P0304
01-014/031999-2000 PROTEGE
ROUGH IDLE, HESITATION
APPLICABLE MODEL(S)/VINS
All 1999 - 2000 Protege 1.8L with VINs lower than JM1BJ221**Y* 283505 or JM1BJ223**Y* 283505.
DESCRIPTION
Some customers may notice a rough idle or hesitation on acceleration. Also, the MIL may illuminate with DTCs P0171 or P0301-P0304 stored in memory. These conditions may be caused by a vacuum leak at the intake manifold gasket.
Customers having this concern should have their vehicle repaired using the following procedure.
REPAIR PROCEDURE
1. Verify customer concern.
2. Use NGS Tester to retrieve any DTCs stored and record Freeze Frame Data.
3. Start engine and select Short Fuel Trim PID (SHRTFT1) and Long Fuel Trim PID (LONGFT1).
NOTE:
High positive values (e.g., +12% or greater) for SHRTFT1 or LONGFT1 stored in Freeze Frame Data, or seen in PID data, may indicate that unmetered air is entering the engine through a vacuum leak at the intake manifold gasket.
4. Spray aerosol carburetor cleaner around intake manifold gasket while watching for changes in idle speed or SHRTFT1 values.
NOTE:
Be sure to spray gasket area under intake runners # )1 and # )4 cylinders.
^ If changes in idle speed or SHRTFT1 indicate a potential vacuum leak, replace the intake manifold gasket according to Workshop Manual (section 01-13B) INTAKE-AIR SYSTEM REMOVAL/INSTALLATION [FP].
^ If NO changes in idle speed or SHRTFT1 are observed, continue to diagnose according to Workshop Manual (section 01-02B) DTC TABLE [FP]
5. Verify repair.
PARTS INFORMATION
WARRANTY INFORMATION
NOTE:
This information applies to verified customer complaints on vehicles covered under normal warranty. Refer to the SRT microfiche for warranty term information.