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Ignition timing is the moment the spark plug fires compared with the piston's position. Set too early, the engine pings on hills. Set too late, it feels flat and runs hot. Route 66 Auto Repair in Upland checks timing with a timing light on distributor engines and with scan data on newer ones, then explains what is off and why. The work is written on your estimate before we touch the distributor.
What are the symptoms of wrong ignition timing?
- Pinging or rattling when climbing the Cajon Pass or the 57
- Hard cranking when the engine is hot
- Sluggish acceleration and poor mileage
- Engine running hotter than usual in summer traffic
What happens when timing is too early or too late?
Advanced timing fires the spark before the ideal moment. Pressure builds while the piston is still rising, and you hear knock. Heavy knock over time can damage pistons and head gaskets, which is why we treat it seriously on older engines that climb grades with a load.
Retarded timing fires late. The burn is still going as the piston drops, so more heat goes into the exhaust and cooling system and less goes into pushing the car. The engine feels lazy and can run warm in stop-and-go traffic on Foothill Blvd.
Can timing be adjusted on a newer car?
Not by hand. Engines with coil-on-plug ignition let the computer set spark timing from sensor readings. If timing is wrong on those, the cause is usually a sensor, a knock problem, or a stretched chain or jumped belt. We read that with a scan tool, and if the mechanical timing is off, the fix is a timing chain repair or belt job, not an adjustment.
How we check and set ignition timing
Step 1: Warm up and connect
We warm the engine and attach a timing light and tachometer, or a scan tool on newer engines.
Step 2: Read base timing
Timing marks are read at the specified idle and compared with the engine's spec.
Step 3: Check advance
We rev the engine and confirm the mechanical and vacuum advance respond as they should.
Step 4: Adjust and verify
On distributor engines, the distributor is rotated to spec and locked, then we road test for knock.
What's included in a timing adjustment
Included on the work order
- 01Timing light check at specified idle
- 02Mechanical and vacuum advance test
- 03Distributor adjustment and lock-down
- 04Knock check on a road test up a grade
Need-now or need-later?
Need now: call
- Heavy pinging under load
- Engine overheating along with sluggish power
Need later: book
- Slight light ping only on a very hot day
- A small timing drift on a classic that runs well
How pricing and timing work
A timing check and adjustment on a distributor engine is usually a short visit. If the advance weights are stuck or the vacuum advance leaks, that becomes a separate quote. On newer engines, the diagnostic fee is stated at the counter before testing. AAA members get 10% off parts and labor, up to $75.
Aftercare
Use the fuel grade your engine was designed for. If a distributor was replaced or moved, bring it in for the full timing adjustment service. If pinging returns, carbon inside the cylinders may be the cause, and our engine performance inspection can check.
Frequently asked questions
Is ignition timing the same as a timing belt?
They are related but different. The timing belt or chain keeps the camshaft and crankshaft in step. Ignition timing is when the spark fires. A jumped belt throws off both, which is why we check mechanical timing when spark timing looks wrong. See timing belt replacement.
Can I set my own timing with a timing light?
On many older engines, yes, if you follow the service procedure, including any connector or vacuum line that must be disconnected. Missing that step is the most common reason home settings end up wrong.
Why does my engine ping only on hot days?
Hot intake air and a hot engine both make knock more likely, so slightly advanced timing can be fine in the morning and ping in August.