Acura 2.5L (152 cu in) firing order — diagram & guide

If you own an older version of the Acura TL, chances are that the 2.5-liter engine lies under the hood. It’s a good engine regardless of the exact variant of it, but things can get messy if you need the Acura 2.5L (152 cu in) firing order.

The thing is – there are two 2.5-liter engines used in Acura models, and they feature a completely different cylinder layout. Naturally, the firing order for each is different and that’s why you’ll need clear guidance brought to you by our automotive experts to solve this puzzle.

Acura 2.5L V6 firing order

The first engine we’ll discuss in this guide is the Acura J25A engine used in some Honda vehicles as well. It made its appearance in the Acura TL back in the early 2000s and the Acura 2.5L V6 firing order is 1-4-2-5-3-6.

This is very important since it’s the firing order suitable only for Honda’s V6 engines, unlike the next engine we’ll discuss. The other 2.5-liter engine used in Acura models is a straight-five engine. This means it has five cylinders and is pretty different from the V6 both in terms of cylinder configuration and the firing order.

Acura 2.5L five-cylinder firing order

Let’s make things clear right away – the Acura 2.5L five-cylinder firing order is 1-2-4-5-3. As you can see, not only is the sequence different but there’s one figure less here since this engine has five cylinders instead of six cylinders like the J25 engine.

This also means that you’ll have a different approach when servicing a car powered by this engine. Now let’s compare the cylinder layouts of both these engines to give you a clear picture of those differences.

Acura 2.5L cylinder diagram

The cylinder arrangement of the Acura 2.5-liter V6 is the same as for the majority of Honda’s V6 engines. You have two cylinder banks housing three cylinders each, and the first cylinder is at the left side bank along with cylinders 2 and 3.

Cylinders 4, 5, and 6 are positioned on the opposite side, and it’s important to note that the first cylinder is at the front end of the engine. On the other hand, the G25 is a straight-five engine which means the cylinders are arranged differently.

This time you’ll have the first cylinder at the front of the engine near the radiator housing, and all the other cylinders spread in sequence from 1 to 5 towards the rear end. This makes the inline-five a much easier engine to work with at least in terms of inspecting the cylinders.

Acura 2.5L vehicle applications

To wrap up this guide, we’ll also give you a list of all the models equipped with both of these engines to make sure you’ll use an adequate firing order for yours. The straight-five engine has been used in the Acura Vigor and the first-generation Acura TL.

On the other hand, these are the vehicles that used the 2.5-liter V6 engine:

• Acura TL (second-generation)
• Honda Inspire
• Honda Saber

As you can see, both these engines were used in Honda and Acura vehicles, since the straight-five has been used in the Honda Inspire as well.

Our take

Well, we hope that this guide helps you understand the firing orders for Acura’s 2.5-liter engines a bit better, as well as to differentiate between those two. It should be easy now that you know how different in terms of cylinder arrangement these two engines are, so you can rely on this article for guidelines.