Integrator Voltage; Lean Mixture; Rich Mixture - Winnebago 1987-1989 LeSharo Service Manual

ENGINE FUEL SYSTEM
INTEGRATOR VOLTAGE
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Integrator Voltage is the "language" used
between the oxygen
(02)
sensor and the ECU
(Electronic Control Unit). Integrator voltage is an
extremely helpful tool in diagnosing engine
problems. This voltage may be monitored
between pins 2 and 7 of diagnostic plug 02.
When the engine is at operating temperature, the
oxygen sensor tells the ECU whether the exhaust
gases going past it are high or low in oxygen
content, which normally indicates either a rich or
lean condition. The ECU receives this information
and adjusts the incoming air/fuel mixture
accordingly.
NOTE: The
O2
sensor is designed to detect only
the oxygen content of the exhaust gases -
it cannot detect unburned fuel.
At normal operating temperature, integrator
voltage fluctuates rapidly. When the engine is
below operating temperature, however, a steady
voltage is indicated. This steady voltage is known
as baseline voltage.
Baseline voltage is usually indicated at a value
between 6 and 7 volts under the following
conditions:
• all lights and electrical devices turned off
• battery fully charged
• battery mode switch in neutral
• radiator cooling fans off
•
O2
sensor disconnected
If baseline voltage is significantly above or below
the normal 6-7 volt range; it may indicate one or
more of the following conditions:
• electrical load drawing from the battery
• dead battery
• charging system malfunction
Three very important things to remember about
Integrator Voltage are:
• Normal integrator voltage should be within 1
volt above baseline voltage.
• High voltage normally indicates a lean airlfuel
mixture
• Low voltage normally indicates a rich airlfuel
mixture.
NOTE: The integrator voltage reading is a very
important tool when diagnosing engine
problems.
C5-1
A sampling of problems and causesare as follows:
LEAN MIXTURE:
1. Vacuum hose(s) leaking or disconnected.
A. Vacuum hose(s) leaking or disconnected.
B. Intake manifold gaskets, leaking or
manifold cracked.
C. EGR valve not seated or open.
D. Idle adjustment screw leaking
E Auxiliary air device leaking
F. Crankcase vent hose leaking or
disconnected
G. Vacuum capsule at automatic
transmission leaking
H. Vacuum advance module on ignition
module leaking or disconnected.
I. Leaking connections at air flow meter
J.
Hoses to thermovalves (all three)
disconnected or thermovalve broken)
K. Defective brake booster, booster valve or
hose.
L. Leaking cruise control servo, dump valve,
vacuum reservoir or leaking hose.
2. Defective or misadjusted air flow meter.
3. Wiring to air flow meter disconnected or bad.
4. Defective oxygen sensor.
5. Defective fuel pressure regulator causing low
fuel pressure
6. Defective electric fuel pump
7. Insufficient fuel volume
8. Valve lash adj ustment
RICH MIXTURE:
1. Defective fuel pressure regulator causing
high fuel pressure.
2. Defective or leaking fuel injector or injectors
3. Leaking cold start injector
4. Electrical malfunction causing cold start
injector to be on all the time.
5. Defective air flow meter
6. Defective oxygen sensor
7. Saturated evaporative emission charcoal
canister.
8. Restricted exhaust system
9. Cam timing adjustment
10. Valve lash adj ustment
11. EGR valve stuck shut
12. Misfiring spark plug(s)
13. Weak or defective ignition system (eg., coil,
ignition module, TDC indicator, exciter ring
on flywheel, distributor, spark plugs, spark
plug wire, etc.)