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.
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HOMESERVICE MANUALSCHEVROLET1988S10/T10 BLAZER 4WD L4-151 2.5LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTIGNITION SYSTEMIGNITION TIMINGADJUSTMENTS
1988 Chevrolet S10/T10 Blazer 4WD L4-151 2.5L
Ignition Timing: Adjustments
1988 Chevrolet S10/T10 Blazer 4WD L4-151 2.5LSECTION Adjustments
NOTE: Timing specifications are listed on the Vehicle Emissions Control Information label under the hood. Always follow the Vehicle Emissions Control Information label procedures first before using the following procedure.
IGNITION TIMING ADJUSTMENT
- Set timing under the following conditions:
- Normal operating temperature.
- Air cleaner installed.
- A/C "OFF".
- Transmission in neutral.
- Put Electronic Spark Timing (EST) in by pass mode. Connect a jumper lead between terminals A and B of the ALDL connector under the dash.
- Connect timing light and adjust to specification as necessary, by loosening hold down bolt and rotating distributor. Specifications
- Tighten hold down bolt and recheck the timing.
- Stop the engine and remove jumper form ALDL connector.
- Clear ECM trouble code by disconnecting ECM power source.
Spark Plug Wire Routing:
IGNITION TIMING ADJUSTMENT
- Set timing under the following conditions:
- Normal operating temperature.
- Air cleaner installed.
- A/C "OFF".
- Transmission in neutral.
- Put Electronic Spark Timing (EST) in by pass mode. Connect a jumper lead between terminals A and B of the ALDL connector under the dash.
ALDL Connector:
TIMING MARK:
- Connect timing light and adjust to specification as necessary, by loosening hold down bolt and rotating distributor. Specifications
- Tighten hold down bolt and recheck the timing.
- Stop the engine and remove jumper form ALDL connector.
- Clear ECM trouble code by disconnecting ECM power source.
RENDER: 1.0x
NO RELATED
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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.