Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET1990S10/T10 BLAZER 2WD V6-173 2.8LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSDESCRIPTION AND OPERATIONOPERATING MODESRUN MODE
1990 Chevrolet S10/T10 Blazer 2WD V6-173 2.8L
Run Mode
1990 Chevrolet S10/T10 Blazer 2WD V6-173 2.8LSECTION Run Mode
The Run Mode consists of two separate operating conditions; open loop and closed loop. The engine operates in open loop when it is first started and RPM is above 400 RPM. During open loop operation, the ECM disregards the oxygen sensor signal and determines air/fuel mixture primarily from the coolant and MAP sensors. The engine will continue to operate in open loop until the following conditions are met:
1. The Oxygen sensor has varying voltage output, indicating it is hot enough to operate properly.
2. The Coolant sensor is above a specified temperature.
3. A specific amount of time has elapsed since the engine was started. The specified values for conditions mentioned above vary from model to model, and are stored in the ECM PROM.
When the above conditions are met, the engine goes into closed loop operation. When operating in closed loop, the ECM determines the air/fuel ratio (injector pulse rate) based on signals from the oxygen sensor. This allows the air/fuel mixture to remain close to the optimum 14.7:1 ratio. During idling conditions, the V6-173 and V8-454 engines automatically goes into open loop operation.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.