Solving Automotive Performance Issues
Once you pull the code(s), follow the diagnostic procedure for that particular code on your vehicle. That information can be found in the service manual for your vehicle. Don’t assume that just because you have a code for something it means that the part you have a code for is bad. This is particularly true for O2 sensor codes. There are several O2 sensor codes, and they don’t all mean that the O2 sensor is bad. In fact, it would be bad practice to replace a part that you had a code for without verifying it was bad first. You can waste your time and money doing this. The problem could just as easily be bad wiring or some other fault that set the code. The computer doesn’t know that a given part is actually bad; all it knows are voltage readings. If the voltage readings are off, then it sets a code. It doesn’t ask why the readings are off; it just sets a code and leaves you to figure out what the issue truly is.
Another thing to note here is that you can often get your local auto parts store to pull codes for you. Keep in mind this is all they can really do. These people are not trained technicians, so any information they give you outside of what the code is should be taken with a grain of salt. It is true that some of them are former technicians or that they might have some mechanical experience, but you should only take their advice as just that, advice. Don’t assume what they tell you is a diagnosis; think of it as more of a jumping-off point. I strongly recommend you get your hands on a service manual for your vehicle and perform the troubleshooting associated with your code(s) before purchasing any parts. This video might help you find a service manual if you need one.
What if you don’t have any codes stored and you still have a performance issue with your vehicle? This is where things can get a bit tricky. One of the first things I do is try to nail down the system where the problem is originating. It could be an engine or transmission problem, or something else, such as an issue with the final drive. It could also be a problem with the brakes, the tires, the engine mounts, or any number of things. One of the first things you can do is determine if it’s an engine problem or an automatic transmission problem. If you have a manual transmission, this test won’t work for you.
Power braking can be dangerous, so use caution when doing this test. Do it in an open area away from things you can run into. You can only do this test with an automatic transmission; you really can’t do this with a manual transmission. The test is simple enough and only takes a few seconds.
- First, start the engine and activate the parking brake.
- Next, put the transmission in drive or reverse, it really doesn’t matter. I often put it into reverse if I’m facing a wall; that way, if the brakes fail or some other issue happens, I can recover before I hit something. I’ve never had to deal with that situation when doing the test, but I’d rather be safe than sorry.
- Next, put your foot on the brake and floor the gas pedal. You only need to do this for a few seconds. Don’t continue to do it for long periods of time, as you can overheat the engine.
- Keep an eye on the tachometer if you have one, as this information can be helpful. Note when the RPMs no longer go up and at what RPM that happens.
This test will tell you two things. The first is the stall speed of the torque converter. The RPM reading you took when the engine peaked is the stall speed of the converter. This information is really secondary to what you’re looking for. You want the problem you’re having to manifest. If it does manifest while you do the test, then the problem is likely with the engine. If the problem does not occur when you do this test, your problem might be with some other system, such as the transmission or another drive line component. Like I said, this is a quick test to determine if your performance issue is the result of an engine problem or something else. The test puts your engine under full load, so if there is an issue with engine performance, it will often show up during the test. Because you’re running the engine under full load, it can overheat it. As I said, you don’t want to do the test for too long; just do it long enough to put the engine under full load and check for a problem.
To begin your diagnosis, you’re going to have to determine the type of problem you’re having. One of the most common problems is a misfire. A misfire can cause an engine to run rough or shake while it runs. Your engine has a given number of cylinders. If one or more of those cylinders isn’t putting up full power, it creates a misfire at that particular cylinder(s). This puts the engine out of balance and causes it to run rough. Misfires can be caused by anything from fuel delivery to a mechanical problem. For me, the first step in diagnosing the source of a misfire is to determine if the misfire is specific to one cylinder or several. An easy way to do this is with a power balance test.
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