If you have ever dyno-tested or tuned your used car (PLEASE INTERLINK THE TUNING ARTICLE ONCE IT IS PUBLISHED), you probably noticed that the initial dyno run results differ from what the manufacturer claims. In most cases the manufacturer did not lie, but your car actually lost some of its proclaimed power.
Usually drivers will not notice slight drops in power ratings. The drops are usually very gradual and they rarely reach the levels that seriously hamper movement. However, depending on how much you mistreat your car and how far apart your maintenance periods are, there can be some serious power drops.
In this article we will explain why power loss occurs, what you can do to prevent it and why this is important. A better understanding of this phenomenon can do you (and your car) lots of good.
There are loads of reasons and many of them can be solved by simple DIY maintenance procedures. Engine rebuilds are rarely required, but not nonexistent.
In fact, this article is a nice little checklist of how you should treat your engine if you want it to serve you properly.
When engines work as they are supposed to, each and every part of the combustion process is perfect. However, if there is a power loss, at least one of the aspects is not as it should be.
In general, the easiest fixes are the ones regarding air intake systems. Most of this you can do yourself. The easiest and probably the most common fix is replacement of the air filter. Replacing the air filter should be a part of regular maintenance, but in some cases they get clogged before they are supposed to. This is most common in sandy or dusty areas. When this happens, your engine does not get enough air and it can’t produce enough power.
If you want to replace your air filter, make sure you buy the right one, since not all of them are the same. Find the air filter housing under the hood, open it and read the part number on the filter. Or ask a car chop employee — most will know which air filters are used in the most common cars. When you buy the right one, simply put it in the housing and close it properly. The housing usually has simple latches.
Speaking of airflow, as the gases leave the engine, their flow also has to be flawless. A clogged catalytic converter can hamper free flow of exhaust gases and reduce power. The same particulates can clog the muffler. You should have an expert deal with these two. They are nothing serious, but there are things to know when dealing with them, so make sure you visit a mechanic if you need to deal with your catalytic converter or muffler and you have no experience with them.
Another thing that can clog is fuel injectors. This usually happens due to bad fuel quality, although there can be other causes. When they don’t operate properly, bad injectors can cause misfiring and even violent jitters when you try to accelerate hard. Simply put, your engine does not get enough fuel and it can’t work properly. Replacing fuel injectors is not very difficult in most cases, but for many cars you need specific tools, including suitable torque wrenches that ensure the injectors are tightened to an exact level. If you’re not experienced and don’t have dedicated tools, make sure you visit a mechanic for this fix.
Speaking of fuel delivery, fuel pumps can fail. They fail gradually and in most cases you will notice that they are failing when you begin lacking power in high revs. They still have enough strength to provide fuel in low load conditions, but they start struggling in more demanding conditions. Bear in mind that the same symptoms can come from malfunctioning of other simpler and cheaper parts, so try replacing things like your air filter before you opt for changing the fuel pump.
If your car has a mechanical throttle cable, it can loosen over time, which means it doesn’t open the throttle valve all the way. In such cases, simply tighten it using the two nuts that you can find somewhere along the cable, usually near the top part of your engine. If you’re not sure which cable that is, open the hood and have someone apply throttle while the gearbox is in neutral. The throttle cable will move as the pedal is pressed. Just make sure you don’t make it too tight, or your throttle valve will be open more than it should all the time. This is probably the easiest fix.
Getting more serious, we reach engine internals. Worn piston rings can reduce compression and result in power loss. They wear over time as they rub against the cylinder wall. Aside from the power loss, you can also often see light smoke coming out the exhaust. To prevent this, or at least postpone it as much as possible, make sure you perform oil changes in time and use proper oil.
If piston rings are the problem, you will need a mechanic, because the engine needs to be opened.
Intake valve deposits can also cause power loss. They can limit the valves’ ability to close properly, which can reduce compression and also cause backfiring. The same problem can also limit air delivery which, just like in the case of a clogged air filter, reduces power. Replacing valves is a job for a mechanic.
Bad spark plugs can cause misfires. They are also a quick and easy fix, but should be done using proper tools.
Faulty filters and sensors can also send wrong information to the ECU and make it adjust air and fuel deliveries, as well as ignition timing, in a bad way. Depending on the car you have, these parts can be DPF, EGR, O2 sensors and similar. Bad information processing can also happen due to faulty wiring. If this happens, your engine will often have uneven idling and not just loss of power.
Lastly, if you had your car tuned for more power, but it was done badly, it can cause power loss. There are several reasons why this can happen and they can cause everything from bad air-fuel ratio to engine knock and serious damage. We have an article explaining the basics of proper engine tuning in layman terms, so make sure you read it before you have your car tuned (PLEASE LINK IT AGAIN).
All in all, if you experience power loss, there are a few things you can try before visiting your mechanic. Checking the throttle cable and air filter would be the easiest and least expensive options, so make sure you check them before anything else.
And always, always perform regular maintenance in its due time.