Engine - Troubleshooting Driveability Complaints: Overview
GROUP: 24NUMBER: 94-7
DATE: Sept. 30, 1994
SUBJECT:
Driveability Complaints (Digifant I), Troubleshooting
MODEL(S):
Cabriolet, Fox w/California emissions 91-93 m.y.
Golf/Jetta w/California emissions 91-92 m.y.
When troubleshooting customer driveability complaints, use the following as a guideline.
Make copies of the checklists (first two pages of this bulletin) to make it easier to record your findings and diagnose the complaint.
Note
Always attach copies of your findings to the repair order as required by the Warranty Policies and Procedures Manual.
Digifant I - Driveability - Repair Procedure
Engine Driveability Diagnostic Work Sheet
DIGIFANT I-DRIVEABILITY-REPAIR PROCEDURE
(Golf/Jetta/Cabriolet/Fox)
Introduction
Customer complaints of poor driveability can occur with today's vehicles. This is most likely to take place during the first few minutes of the vehicle's operation for example, after first driving away in the morning. These symptoms can result from several factors.
The majority of exhaust emissions are produced in the first few minutes of operation, after the engine is first started. Federal emissions measured during this warm-up period have become more stringent In recent years. To comply with these regulations, automobile manufacturers have had to take measures to reduce these emissions.
The lean fuel mixtures that result from these efforts to reduce emissions, combined with cold engine parts, varying ambient temperature and humidity conditions, and different fuel qualities, reduce the engine's tolerance for any disturbances in the intake air/fuel mixture formation and combustion.
The following procedures will help minimize the occurrence of these driveability complaints by assuring that:
^ Any stored DTC's have been repaired
^ The vehicle meets the latest technical specifications.
After completing all the steps described here, some slight idle fluctuation may still briefly occur during engine warm-up. This is normal due to the design of the system
CARBON DEPOSITS
The driveability complaint may be caused by carbon deposits on the fuel injectors, intake ports and intake valves.
First perform a carbon check and removal of carbon, if required, as described in the "Solving Driveability Complaints" Handbook.
If the driveability complaint remains, follow the repair procedure contained in this bulletin.