Toyota-Lexus-Scion Tune & Tune Checks
People have an incredibly wide range of perceptions as to what a tune-up entails.
Both among consumers and shops, this range includes everything from the most minimal possible of simply replacing the spark plugs, on out to include spark plugs and filters and a full major 60k or 90k service with all the fluids being changed and the timing belt replaced also.
The following tune description is a composite description that describes tune procedures for vehicles with several generations of developments, including:
- Carbureted and fuel injected. Those with vacuum advance and mechanical advance and those that have electronically controlled timing.
- Ignition systems with distributors and distributorless ignition systems with ignition coils directly over the spark plugs.
- Vehicles with no onboard diagnostics built in; vehicles with first-generation onboard diagnostics that are accessed through jumper wires and blinking-light codes; and vehicles with second-generation diagnostics that are accessed through full computer hook-up.
Our composite working definition is below:
- Test drive before beginning
- Scan test if OBII (onboard diagnostics 2nd generation)
- Scope check those that allow standard inductive hook-up to secondary ignition
- Replace spark plugs
- Replace air filter if dirty, and the fuel filter for carbureted models
- Full voltage test of rotor (those that allow standard inductive hook-up)
- Wet test cap & wires for voltage leaks. Check insulators for leakage where they pass through spark plug tubes.
- Manually check high-tension connections at coil and cap for corrosion
- Note whether cap, rotor & wires are factory or aftermarket
- Clean top surface of coil (coil-in-cap models)
- Check and adjust timing when applicable
- Does jumper connection cause timing to change?
- Verify that TPS contacts are engaging. If necessary, bypass to set timing. (Bottom two terminals on most) Mechanical advance free?
- Diaphragms not ruptured?
- Able to move breaker plate?
- Gets proper vacuum signal?
Check EGR system.
- Does EGR valve get vacuum signal?
- Does EGR kill engine or cause a significant rpm drop at idle
- Cycles back and forth quickly?
- Operates over full range when made lean and rich?
- Check whether throttle valve sticks in throttle body.
- Adjust idle speed when appropriate. Emphasize smooth idle & not dieseling over exact rpm specs.
- Carbureted: Clean and lubricate choke
- Some carbureted: Drill & adjust mixture (only on accessible carbs) when exhibiting lean idle condition.
- Cleaner and penetrating oil through auxiliary air regulator
- Compression check if engine running suggests problem Quick check emissions if:
Car approaching license renewal date
Symptoms suggest emission reading could give useful diagnostic information
Check fluids in engine compartment
Test drive again after work completed
Certified Independent Toyota, Lexus & Scion automotive service and repair specialists serving PDX, Portland, Fairview, Forest Grove, Gladstone, Gresham, Happy Valley, Johnson City, Beaverton, Clackamas, Oregon City, Fairview, Wood Village, Maywood Park, Milwaukie, Oak Grove, Troutdale.