For the 4-cylinder turbo engines (mainly represented now with the 1.5 TSI), Volkswagen introduced its Active Cylinder Technology (ACT) about a decade ago. This is the technology that turns off or on two of the cylinders depending on the engine load at a certain moment.
The ACT system does have problems and makes the engine vibrate and jerk, sometimes very significantly. But deactivating it is not a good option, in most cases.
In this article, I will tell you more about the ACT system and share my opinion on what you may try doing with it to get fewer problems. Also, I will share the opinion of mechanics on whether this system is going to harm your engine.
Does ACT really have problems in Volkswagen cars?
In different generations, the settings for this system are various. While in some years, the ACT only activated after the car reached 50 MPH (80 km/h), in many modern models it will work at any speed.
Usually, when the system activates, you see the light on your dash telling you about that. And if you are attentive enough, you may feel some jerking, vibrations, and resonation from your engine that may actually be disturbing.
I should say that some engines are better and some are worse, but an experienced driver will always feel this change when the cylinders are activated or deactivated.
Here are the potential problems that this system may eventually lead to:
- Engine jerking and vibration may lead to several issues like engine mount problems, wiring clamps falling off, etc.
- High mileage engines may eventually fail to activate the cylinders and you will have the power of the lawn mower whatever you do.
- Two cylinders that are often deactivated will obviously be in better condition, while the other two will get more load and die much sooner.
- The technology itself is pretty complicated and applies actuators that may not be as reliable as you want them to be.
- Potential internal oil leaks – the ACT actuators are obviously lubricated by engine oil and may eventually cause some leaks.
- The technology will affect high-mileage engines and reduce the overall durability of the machine reportedly by 15-20%.
Also, the system uses modified camshafts. The actuators move the part of this shaft to prevent the intake valves from opening and letting air and fuel inside the combustion chamber. This modified camshaft proves to be problematic at high mileage, too.
But I wouldn’t say that the system is super-problematic and will cause a lot of failures. If compared to other cylinder management systems out on the market, I should say that the ACT in Volkswagen’s 1.5 TSI engine works more or less well.
Why do VW owners still want to deactivate ACT?
First of all, they mostly know about the high-mileage problems. While the 1.5 TSI is not the worst VW engine, it may fail earlier and require replacement or very expensive repairs if used with the ACT all the time.
If the ACT is deactivated, Volkswagen owners get two serious benefits: they don’t kill their engines earlier and they get rid of vibrations and jerking.
But before you run to unplug those ACT actuators, I should warn you that deactivating this system is not that easy. If you just unplug the actuators, the engine may not work well and the warning message will hang on the dash.
How can you properly deactivate the ACT system?
Well, I should say that I don’t recommend deactivating the ACT system and there are several reasons I will outline later.
But for those curious readers, I will say what I know. Deactivating this system is possible with several unofficial software and firmware updates. You will need to find a good VW tune guy who knows what to do.
The easiest way is to raise the lower speed limit to 120 km/h. The system is set by VW to work up until the vehicle reaches 130 km/h. So, you will rarely see the system activate and this will solve your problems.
But a good tune professional can completely deactivate the system.
Why isn’t deactivating ACT a good solution?
Well, first of all, you need to understand the guidelines of your insurance. I know about a case in France when the insurance company refused to pay a VW owner because he had made several upgrades to the engine. French insurance companies are pretty severe, but I believe many European countries may have this rule.
Also, any upgrades like this may void the warranty. While your Volkswagen may not already have the bumper-to-bumper warranty, it may still have the powertrain warranty. And voiding it with your own hands for the sake of not having the minor vibration in your car is not the best solution.
When it comes to fuel consumption, I don’t see any serious effect that the ACT can propose to you. All Volkswagen owners that I’ve spoken to told me that the difference maybe something like 1-3% and only on highways.
My personal concerns about technology
While some other manufacturers use software solutions to cut the fuel supply to the cylinders, Volkswagen uses firmware technology. It has two actuators that are placed on top of cylinders 2 and 3.
These two actuators are the first reason for concern. They may fail or cause an inner oil leak that you will not even know about. If one actuator fails, it may eventually turn your 4-cylinder engine into the shaking 3-cylinder freak.
Also, other technologies may deactivate different cylinders while the ACT in 1.5 TSI (and 1.4 TSI also) can only deactivate cylinders 2 and 3. This means that the inner cylinders in your engine will most likely be in much better condition. While the outer cylinders (1 and 4) will see some life.
Of course, this will inevitably reduce the lifespan of the engine. In my opinion, the 1.5 TSI may run over 250,000 kilometers but it will drive up to 200,000 kilometers with the ACT activated.
By the way, lots of people ask if the 1.5 eTSI (mild-hybrid) has this ACT system. Yes, according to Volkswagen, it comes with the ACT.
Why did Volkswagen at all introduce this system?
After you’ve read the article, you may still have one question that wasn’t answered. Let’s address it right now.
So, Volkswagen introduced the Active Cylinder Technology in 2013-2014 to try and squeeze the 1.4 TSI engine through new emission rules. Actually, the entire cylinder-management madness is now happening as a way to try and prolong the life of the petrol-driven engines on the market with changing emission rules.
No, there isn’t much benefit in terms of fuel consumption and comfort of driving. It’s only about the emissions. By the way, I doubt that emissions are greatly reduced. Emissions on modern engines depend highly on fuel consumption. And I see no serious difference in fuel consumption with or without ACT.
Added: Oh, and the last question – is the ACT somehow connected to the kangaroo effect in the VW 1.5 TSI engines? No, it isn’t connected. The kangaroo is obviously the software problem that Volkswagen hasn’t yet fully understood itself. The ACT has nothing to do with it.
