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Fuel Injection - System Cleaning And Decarbonization: Overview

88vw12

GROUP

25

NUMBER

88-06 December 23, 1988


MODEL(S):

All VW's equipped

w/ CIS or CIS-E w/ air shrouded injectors
SUBJECT:

Fuel injection system cleaning and intake valve decarbonization

(Supercedes Tech. Info. 88-02, dated July 21, 1988)
Vehicles equipped with CIS or CIS-E fuel injection sometimes experience driveability problems such as rough idle, 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 injectors and/or fuel distributor gummed 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 4 Step 4. Carbon Build-up Removing, page 8



Required Tools

- VW 1367 Engine Tester
- SUN 105 Exhaust Analyzer
- flex light (high intensity)
- inspection mirror
- fuel injector insert removal tool US 1123
- fuel injection system cleaning adapter kit US G16