What all VW Enthusiast should know...
CIS and CIS-E Diagnostics
CIS-E Jetronic & Motronic table located below!
CIS TROUBLESHOOTING
SYMPTON Probable
Cause CORRECTIVE
ACTION
1. Cold start-Engine starts hard or fails to start. a.Cold start valve or thermo-time switch faulty
bFuel pump not running
c,Air flow sensor plate position incorrect
d.Fuel pump pressure incorrect a. Test cold start valve and thermo-time switch
b.Check fuel pump fuse & relay
c. Inspect/adjust
d.Test system and cold-control pressures
2.Hot start-Engine starts hard or fails to start a. Hot start pulse relay faulty
b.Cold start valve leaking or operating continually
c.Fuel pressure incorrect
d.Air low sensor plate rest position incorrect
a. Test/replace hot start pulse relay
b. Test valve and thermo-time switch
c. Test warm control pressure
d. Inspect/adjust
e.Insufficient residual fuel pressure
f.Fuel leak(s) e.Test residual pressure.Check fuel pump check valve and accumulator.
f. Inspect all lines and fittings.
3.Engine misses and hesitates under load a. Fuel injector(s) clogged
b.Fuel pressure incorrect
c.Fuel leak(s) a. Test injectors $ lines. Clean/replace.
b.Test system pressure and warm control pressure. Replace pressure regulator if faulty
c.Inspect all lines and fittings.
4. Engine starts but stalls at idle a.Incorrect fuel pressure
b.Cold start valve leaking
c.Auxiliary air regulator faulty
d.Vacumn leak a.Test system/control pressures
b. Test/replace
c.Test/replace
d. Check for leaking hoses, cracks in air intake components,leaking valve cover.
5. Engine idles too fast a. Accelerator cable,pedal,Tbody binding
b. Auxiliary air valve faulty
c.Air leaking past Tbody a.Inspect for worn or broken parts.
b.Test/replace
c.Inspect/adjust/replace Tbody
6. Hesitation during acceleration a.Vacumn leak
b. Fuel injector(s) clogged
c.Cold start valve leaking
d. Control plunger binding or fuel distributor faulty a. See 4d
b. See 3a
c,See 4b
d. Check sensor plate movement/clean control pluger/replace fuel distributor
e. Airflow sensor plate misaligned
f. Fuel pressure incorrect
g.Idle mixture(%CO2)incorrect e.Inspect/adjust
f.Check system/control pressure. Replace control pressur regulator
g. Check/adjust
7. Poor fuel economy a.Idle speed/timing/%CO out of adjustment
b.Cold start valve leaking
c.Fuel pressure incorrect a. Check/adjust
b.Test/replace
c.See 6f
8.Engine runs after shutoff (diesels) a. Incorrect timing or faulty ignitiion
bEngine overheated a. Adjust timing/See IGNITION section
b. Check cooling system
CIS-E and CIS-E MOTRONIC TROUBLESHOOTING
SYMPTOM PROBABLE
CAUSE CORRECTIVE
ACTION
1. Cold Start-Engine fails to start or starts hard. a Cold start valve or thermo-time switch faulty
B.Fuel pump not running
c. Airflow sensor plate rest position wrong Test cold start valve and thermo-time switch.
b.Check fuse and relay.
c. Inspect/adjust
d. Fuel pressure incorrect
e. Coolant temp sensor faulty or wire broken
f. Poor ignition system ground d.Check for leaks. Check differential press. regulator, system and control pressure.
e. Test coolant temp. sensor. Test wiring for continuity.
f. SEE ignition
2.Hot Start-Engine starts hard or fails to start a. Cold start valve leaking or operating continuously.
b. Fuel pressure incorrect.
c. Insufficient residual fuel pressure.
d. Oxygen sensor system faulty a. Test cold start valve and thermo-time switch.
b. See 1d
c. Test/replace accumulator and fuel pump check valve.
See EXHAUST/EMISSIONS
e. Air flow sensor plate position incorrect.
f. Fuel injector(s) faulty.
g. Inadequate fuel delivery
h. Evaporative emission control system faulty on Motronic system. e. Inspect and adjust.
f. Test/clean/replace.
g.Test/replace pump.
h. Check both evaporative control valves/replace.
3. Engine stalls or idles rough a. Fuel pressure incorrect
b. Cold start valve faulty.
c. Fuel injector(s) faulty.
d. Coolant temperature sensor faulty or wiring to sensor broken.
e.Vacumn(intake air) leak. a.See 1d
b.Test/replace valve.
c.Test/clean/replace.
d. Test sensor resistance. test continuity of wiring to sensor.
e.Check valve cover, hoses, plenum, etc.
f. Control plunger binding or fuel distributor faulty.
g.Auxiliary air regulator faulty.
h. Idle air stabilizer valve not operating.
i. Airflow sensor plate position wrong.
j. Incorrect enrichment. f. Test/clean control plunger. replace fuel distributor as necessary.
g. Test/replace.
h. Check wiring/idle switch. Clean ISV.
i. Inspect and adjust.
j. Check wiring/control current to DPR.
4. Engine misses or hesitates under load. a. Fuel injector(s) clogged.
b. Fuel pressure incorrect.
c. Oxygen sensor system faulty.
d. Fuel leaks.
e. Coolant temperature sensor faulty or wiring to sensor broken. a. Clean/test/replace.
b. See 1d
c. See EXHAUST/EMISSIONS
d. Inspect lines/fittings. Correct leaks.
e. See 3d
5. Engine idles too fast a. Accel. cable, pedal, throttle valve binding.
b. Auxiliary air valve faulty.
c. Idle boost valve(s) faulty.
d. Idle air stabilizer valve faulty.
e. Air bypassing throttle body.
f. Evap. emission control faulty (Motronic) a. Check/repair/replace components.
b. Test/replace.
c. Test/replace.
d. See 3h
e. Check hoses/fittings/tbody.
f. Check both control valves/hoses.
6. Hesitation on acceleration a. Vacumn (intake air) leak
b. Fuel injector(s) clogged.
c. Cold start valve leaking.
d. Control plunger binding/fuel distr. faulty.
e. Airflow sensor plate misadjusted.
f. Fuel pressure incorrect.
g.Airflow sensor potentiometer faulty
h. Inadequate fuel enrichment a. See 3e
b. Clean/test/replace.
c.Test/replace.
d. See 3f
e. Inspect/adjust
f. See 1d.
g. Test/adjust/repace.
h. Check wiring/control current to DPR
7. Low power a. Coolant temperature sensor faulty or wiring broken.
b. Fuel pressure incorrect.
c. Throttle plate not opening fully. a. Test coolant sensor resistance values. Check for broken wiring to sensor.
b. Check differential and system pressures. Check DPR.
c. Check adjustment of throttle cable.
d. Full throttle switch faulty or incorrectly adjusted.
e. Airflow sensor screen damaged, clogged, or incorrectly installed.
f. Air filter clogged. d. Check and adjust position of full throttle switch. Replace if faulty.
e. Check installation. Clean/replace screen as necessary.
f. Replace.
8. Poor fuel economy a. Idle speed,timing,CO mixture incorrect.
b. Cold start valve leaking.
c. Fuel pressure incorrect. a. Check/adjust all.
b.Test/replace.
c. See 7b.
9. Engine continues to run after shutoff (diesels) a. Incorrect timing/faulty ignition.
b. Cold start valve leaking.
c. Leaking fuel injector(s)
d. Airflow plate/plunger misadjusted.
e.Evaporative control valve faulty.
f. Engine overheated.
a. See IGNITION
b. Test/replace
c. Clean/test/replace.
d. Inspect/adjust.
e. Check/replace vavle.
f. See COOLING SYSTEM
Technical Information
