Daewoo MATIZ Service Manual page 390

1F – 292 ENGINE CONTROLS
Definition: Momentary lack of response as the accelera-
tor is pushed down. This can occur at any vehicle speed.
It is usually the most severe when first trying to make the
vehicle move, as from a stop. Hesitation, sag, or
stumble may cause the engine to stall if severe enough.
Step
Were the Important Preliminary Checks performed?
1
1. Check the fuel system pressure. If the pressure is
not within the value specified, service the fuel
system as needed.
2. Inspect the Throttle Position (TP) sensor for
2
binding or sticking. The TP sensor voltage should
increase at a steady rate as the throttle is moved
toward Wide Open Throttle (WOT).
Is the problem found?
Repair or replace any components as needed.
3
Is the repair complete?
1. Check the Manifold Absolute Pressure (MAP)
sensor response and accuracy.
2. Inspect the fuel for water contamination.
4
3. Check the Evaporative Emission (EVAP) Canister
Purge System for proper operation.
Is the problem found?
Repair or replace any components as needed.
5
Is the repair complete?
1. Disconnect all of the fuel injector harness
connectors.
2. Connect an injector test light between the
6
harness terminals of each fuel injector.
3. Note the test light while cranking the engine.
Does the test light blink on all connectors?
1. Repair or replace the faulty fuel injector drive
harness, the connector, or the connector terminal.
2. If the connections and the harnesses are good,
7
replace the Engine Control Module (ECM).
Is the repair complete?
Measure the resistance of each fuel injector.
Is the fuel injector resistance within the value
8
specified (the resistance will increase slightly at
higher temperatures)?
Replace any of the fuel injectors with a resistance
that is out of specifications.
9
Is the repair complete?
Perform an injector diagnosis.
10
Is the problem found?
Replace any restricted or leaking fuel injectors.
11
Is the repair complete?
Check the fuel system pressure after a cold start or
during moderate or full throttle acceleration.
12
Is the fuel pressure within specifications?
HESITATION, SAG, STUMBLE
Action
Important: Before diagnosing this condition, check ser-
vice bulletins for PROM updates.
Value(s)
–
Go to Step 2
380 kPa
(55 psi) Go to Step 3
–
System OK
–
Go to Step 5
–
System OK
–
Go to Step 8
–
System OK
11.6–12.4 Ω
Go to Step 10
–
System OK
–
Go to Step 11
–
System OK
380 kPa
(55 psi) Go to Step 14
Yes No
Go to
"Important
Preliminary
Checks"
Go to Step 4
–
Go to Step 6
–
Go to Step 7
–
Go to Step 9
–
Go to Step 12
–
Go to Step 13
DAEWOO M-150 BL2