A Guide to Injection Timing: What It Is, and How to Adjust It

September 23, 2021 Published by Leave your thoughts

If there’s one thing car enthusiasts love to do, it’s tweaking their vehicles, specifically their engines. With the number of moving parts and components in a car’s engine, there’s a seemingly infinite number of things you can do to improve performance, efficiency or emissions.

One tweak that’s specifically relevant to diesel engines is fuel injection timing. Fuel injection timing is a process that involves the fuel injection pump that you can tinker with to improve your engine’s functioning.

This article will cover the basics of fuel injection timing and how to adjust it to your liking.

What is fuel injection timing?

An internal combustion engine is made up of cylinders that rotate and fire, but for combustion to take place, fuel needs to be injected into the cylinders by the fuel injection pump. The fuel can be injected at a few different points during the firing process of the cylinder, giving a few different results.

Usually, the manufacturer sets the fuel injection timing to produce the most power while remaining inside acceptable emissions limits, but you’re able to change this if you wish. There are a few reasons why you might want to do that.

Why you might want to change the fuel injection timing

If your engine is old, or if you’ve replaced certain parts on it like the timing belt or the fuel injection pump, you might want to tweak the fuel injection system to ensure it’s working correctly. Adjusting the fuel injection timing could also help with your engine’s starting difficulties, overheating problems or fuel inefficiencies. It could even help if smoke is coming out during starting and acceleration.

How to adjust your fuel injection timing

When adjusting your fuel injection timing, you can either advance or retard the injection. Advancing the timing means you’re causing the injection to happen earlier than it normally would, and retarding the timing is when you make ignition occur after the manufacturer originally intended it to. Most people adjusting the fuel injection timing want to advance it due to the accompanying performance benefits.

Here are a few ways to adjust your fuel injection timing:

  • Programming the ECM: You’ll probably need a mechanic’s help with this, but you can alter the fuel injection timing by simply reprogramming the engine control module (ECM), which is a computer that serves as the brain of the engine. You won’t have to do any mechanical work, but you will need a Flash tool to do the reprogramming.
  • Adjust the fuel injection pump: You’ll need to be very careful if you elect to do this yourself, as small modifications can result in large changes to the fuel injection timing, which can have adverse effects on your engine. This requires a screwdriver, socket wrench, timing meter and considerable research to find step-by-step instructions.
  • Change out the camshaft: Replacing the existing camshaft with a new one with different sized holes and lobes would change the fuel injection timing. Working with an expert is recommended, though, because of the mathematical complexities involved in the process.
  • Swap out the cam followers and gaskets: This is a similar but cheaper option than replacing the camshaft, as the thickness of the new gaskets would affect fuel injection timing one way or the other.

Call to adjust your fuel injection timing today

When adjusting your fuel injection timing, it’s best to have the input of experts. That’s where we come in. Give us a call at Coastal Diesel Injection, and our technicians will have your engine running powerfully and efficiently in no time.

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