Solving Automotive Performance Issues
Vehicle performance problems can result from anything from engine performance issues to problems with the driveline. The first step with any performance problem is to try to isolate the source of the problem. With a little time and some detective work, you should be able to identify the problem and begin your repair.
Before we get too deep into this complex topic, it’s worth mentioning that you should always check the basics when you have a performance problem with your vehicle. You’d be amazed at how just doing a tune-up on an engine can cure a whole host of problems. In fact, I’d insist that you check these things prior to your diagnosis. Check your spark plugs, air filter, fuel filter (if your vehicle has one), distributor cap and rotor (if equipped), and the oil level. Keep It Simple Stupid, the rule of K.I.S.S., is something to live by when it comes to performance diagnosis.
Many of you come to me with complex assumptions that some sensor somewhere is causing all your problems. This is the way of the dark side; avoid it. Follow the evidence, and you will find the truth. Assumptions waste your time and money. Why not start by checking the oil? On more than one occasion, an engine has had a loss of power and the cause was low or no oil in the crankcase. No kidding. Remember the movie Sling Blade? The main character, who is a lawnmower mechanic, walks over to a couple of guys working on a mower who are scratching their heads trying to figure out why a mower won’t start. The main character removes the gas cap and says, “It’s got no gas in it.” Sure, laugh now, but the truth is you might be guilty of this very thing. I know I’ve been guilty of it a time or two.
Check the oil, check to see if it’s got gas in it, check the tune-up items, look for simple things. Don’t waste your time looking for complex solutions. Just because you view a computer-controlled engine as a complex machine, it doesn’t mean it is. It still needs oil, it still needs gas, it needs air to breathe and a good set of spark plugs, and it needs to be in time and mechanically sound. All those computer-controlled components are there to make sure it performs well under a variety of conditions; the engine still works the same as it did a hundred years ago. Remember, K.I.S.S. and you might just save yourself a bunch of time and money.
One of the easiest things to check for are any indicator lights that might be on the instrument cluster. If you have a check engine light (CEL/MIL) or other warning light, this is the best place to begin your search for the cause of a performance problem. In fact, even if you don’t have a check engine light on, pull the codes. You may find you have codes stored with no indicator on the dash. It wouldn’t be the first time this has happened. Sometimes the bulb burns out, or someone has disabled it for whatever reason. It’s for that reason you should check for codes first thing even if you don’t have a CEL. These lights are often associated with a particular code that could indicate a system fault. These codes are created and stored in the PCM (Powertrain Control Module) to aid in the diagnosis of a particular fault. Codes can represent problems with the engine or its management systems, the transmission and its systems, the ABS (Antilock Brake System) or TCS (Traction Control Systems); even a problem with the ABS or braking system can cause a performance problem.
Sometimes when a given fault is registered by the computer, it puts your vehicle into what is called limp-in mode. This limp-in mode is designed to preserve the engine and transmission during a particular fault. In the process of putting the vehicle into limp-in mode, it limits certain functions, such as the maximum RPM your engine will rev or the timing of the transmission shifts. This is a measure of self preservation to the drive train; it also gives you the ability to make it to the nearest service center to have things checked out before you damage something.
So for starters, pull any codes you might have. As stated, it’s not a bad idea to check for codes even if you don’t have any dash warning lights on; sometimes the lights have burned out or been disabled. If this is the case, the codes will still be stored in memory, but you won’t see the warning lights on the dash to indicate a fault has been detected. Here’s a video on pulling these codes.
On vehicles older than 1996, you might need to follow a different procedure. Every manufacturer before that time had their own way of storing and presenting fault codes. The upside is that these vehicles often don’t require that you hook up a scanner to retrieve codes. Check your service manual for the procedure for your vehicle. You might find this video on how to pull codes from a Honda or Acura without a scanner helpful. Consult the service manual for specifics on the vehicle you’re working on.
Video Title: Solving Automotive Idle Problems – EricTheCarGuy Video Description: In this Article, Solving Automotive Performance Issues, Eric looks at what can be the cause of Solving Automotive Performance Issues with your vehicle .Thumbnail: http://www.ericthecarguy.com/images/faq_buttons/Large_FAQ_Images/Performance-and-Driveability-icon-large.png