Fuel Injection - Cleaning/Intake Valve Decarbonization: Overview
89vw05GROUP
24
NUMBER
89-04 April 24, 1989
MODEL(S):
Vanagon, 1986-present
SUBJECT:
Digifant I: Fuel injection system cleaning and intake valve decarbonization (Supercedes 89-02, dated March 31, 1989)
Vehicles equipped with a Digifant fuel/ignition Management system sometimes experience driveability problems such as rough idle, stalling, bucking, or poor acceleration, primarily during warm-up. Driveability problems are frequently related to the use of gasoline with insufficient cleaning additives which will lead to the following conditions:
^ Fuel injector gum-up, fuel injector tips clogged by varnish and carbon deposits
^ Carbon build-up on intake valves and/or intake ports
This Technical Information Bulletin (broken into 4 steps) provides repair information to eliminate the driveability problems described above.
Step 1. Preliminary Checks, page 2 Step 2. Carbon Build-up Diagnosis, page 2 Step 3. Fuel Injection System Cleaning, page 3 Step 4. Carbon Build-up Removing, page 6
Required Tools
^ VW 1367 Engine Tester VW 1473 Voltage Splitter
^ SUN 105 Exhaust Analyzer (or EPA equivalent) SUN 120.239 Adapter Hose
^ US G16 Kit for Cleaning CIS Injection Systems and Adapter Fitting for Digifant
^ VW 1318 Fuel Pressure Gauge and VW 1318/17 Adapter Hose for Digifant
^ flex light (high intensity)
^ inspection mirror
Note If any hose clamps require replacement; use P/N: N 900 213 01 or N 024 12 22.