# Diesel Engine Timing Adjustment in Upland > Hard starts, knock or smoke on an older diesel? Route 66 Auto Repair in Upland checks injection timing and resets it to factory spec after a written estimate. Source: https://route66autorepairshop.com/diesel-engine-services/diesel-engine-timing-adjustment Updated: 2026-09-17 Business: Route 66 Auto Repair, 1775 W Foothill Blvd, Upland, CA 91786, (909) 608-7699 Hours: Monday to Friday 8 AM–5 PM, Saturday 8 AM–2 PM, Sunday closed **TLDR:** Wrong injection timing causes **hard starts, knock and smoke**. We check it, and we reset it to **factory specification** only. Diesel engine timing adjustment sets when fuel enters the cylinder so combustion happens at the right moment. Route 66 Auto Repair in Upland checks and resets injection timing to factory specification on diesel pickups and vans, most often older engines with mechanical injection pumps. On newer common-rail engines the computer controls timing, so we diagnose the sensors and data that feed it. We return timing to spec only; we do not change it for power. ## What are the signs diesel timing is off? - Long cranking on cool mornings, even with good glow plugs - White smoke at startup that lingers longer than it used to - Louder knock than normal, especially under load - Black smoke and lazy power climbing a grade - Symptoms that began after a pump or timing gear job ## Mechanical pump or computer control? On an older diesel with a mechanical injection pump, timing is set by the pump's position on the engine. It can drift if the pump mounting moves, or change after a timing gear or belt job. Resetting it is a measured, physical adjustment. On a common-rail engine, the engine computer decides timing from crank and cam sensors. There is nothing to rotate. If those sensors read wrong, or the cam and crank are out of phase, the computer times fuel poorly. Our [diesel engine diagnostics](https://route66autorepairshop.com/diesel-engine-services/diesel-engine-diagnostics) process sorts out which case you have. ## Our diesel timing adjustment process 1. **Identify the system:** We confirm the injection system type and look up the factory timing specification. 2. **Measure:** Timing is checked with the tool that fits the engine: a dial indicator, timing marks or live sensor data. 3. **Adjust or diagnose:** A mechanical pump is rotated to spec and locked; an electronic system gets a sensor and phase check instead. 4. **Confirm on the road:** We road test for smoke, knock and cold start behavior, then record the final reading. ## What's included in a diesel timing adjustment - Injection system identification and spec lookup - Static or dynamic timing measurement - Pump adjustment and mount torque, where applicable - Crank and cam sensor data review on electronic engines - Before and after readings on the repair order - Road test for smoke and knock ## Is it a need-now or need-later repair? **Need now:** - Timing moved after a recent repair and the engine knocks hard - A no-start tied to a cam and crank correlation code **Need later:** - Slightly longer cold starts with no other symptoms - Light smoke at startup that clears quickly ## How pricing and timing work On many older engines a timing check is a modest job. Pumps buried under intake parts, or engines that need special locking tools, take longer. If the pump itself is worn, adjusting it will not help, and we explain the options on the [diesel injection pump repair](https://route66autorepairshop.com/diesel-engine-services/diesel-injection-pump-repair) page. You approve a written estimate first. ## Aftercare Starts should be quicker and the idle smoother. If knock or smoke returns, we recheck the reading. Pumps that will not hold spec may need [diesel injector pump calibration](https://route66autorepairshop.com/diesel-engine-services/diesel-injector-pump-calibration). ## Frequently asked questions ### Will advancing the timing give me more power? We do not change timing for power. Timing outside factory spec raises cylinder pressure and heat, and it can affect emissions. We set it where the manufacturer specifies. ### Does my newer diesel ever need a timing adjustment? Not in the old sense. The computer controls it. When a newer truck acts like its timing is off, the cause is usually a sensor, an injector or a timing component, which we diagnose. ### Can timing change on its own? On a mechanical pump, loose mounting bolts or a worn drive can let it creep. It is more common after other repairs moved the pump or timing parts. --- Call (909) 608-7699 or visit https://route66autorepairshop.com/contact for a written estimate.