Solving Automotive Performance Issues
After You Get the Codes
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.
Performance Diagnosis, No Codes
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 Test or Stall Speed Test
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.
Diagnosing Engine Problems
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
13 thoughts on “Solving Automotive Performance Issues”
Giovanni Alfonso
November 3, 2022 at 1:19 pm
Good afternoon Eric , I have a 2007 ford expedition EL Eddie Baur. I have codes P0172,P0175. I have spent a lot of money changing parts. I have changes everything that I can think of when coming to a car running rich. And the car is still running rich i don’t know what else to do. I have changes o2 sensors all of them, fuel filter, fuel pump, spark plugs, injectors, purge valve, MAF sensor ECT sensor both Catalytic converters. Can you please help me. Oh and also took my computer to get looked at and they told me is fine.
Iliya
July 18, 2022 at 6:57 am
Love your videos Eric 🙂 I have a Suzuki alto 2011, and in the last
3 years ,sometime, randomly, especially (but not only) in the first 5 -10 minutes of its operation, the viechle stalls when I press the clutch pedal during ride. I start the engine immediately back on without any problem. It might occur
1 to 4 times during those 10 minutes, and then mostly it keeps driving without any problem after that (it might not stall at all in the first place). A side note is that it happens more often during winter. The OBD scanner reveals nothing and no other obvious sign appears (a very rare ESP light might appears but I don’t think it relates to the mentioned problem), but I suspect that its about a dirty throttle body, and maybe a simple clean up will hopefully solve the problem. But before I do that (its a little complicated in my car) I would like to hear your thoughts about it… again, I really appreciate your work and hope to hear your answer or somebody’s else in the audience 🙂
ישראל נוישטט
August 3, 2022 at 4:51 pm
hi how did you rezolve the cars problem
I have it too in my suzuki car
Ralph Bowes
February 21, 2022 at 3:37 pm
Hi Eric,
I love your channel. I have a 2007 Ford F150 with a 5.4l. It will barely move. Max speed maybe 5 mph. It runs good in park and you can rev the engine but as soon as you put it in gear you have no power. The rpms do not go up past 1500. I ran codes and I got p0300, p0305, p0306, p0308, p0316 and p0420. Could you please give me an idea about what is going on or possibly where to start? Thank you have a great day!
Northshore
March 31, 2022 at 5:02 pm
Plugged cat
Eli
January 24, 2022 at 5:33 am
Hi Eric,
I own a 2003 Acura CL Type-S with a 6-speed manual(195k miles). I have a a random misfire on an assortment of cylinders for some time now. I have replaced/serviced the following: the spark plugs, coils, valve adjustment, valve cover gaskets, plenum gasket, EGR port cleaning, EGR Gasket replacement, and throttle body gasket, and checked for vacuum leaks. I was wondering where the next step would be to try to resolve this issue. There is a little electrical whine when I accelerate (maybe bad ground(?)) and I was curious if you think that could trigger that many misfires. Any direction or advice is much appreciated. Thank you and have a good day
Eddie
April 25, 2022 at 11:47 pm
Hi Eric I in need if help if u would please contact me back i have a 98 honda civic runs good motor warms uo the. It hesitates an bearly moves let it set an cool down works fine
Gabe
March 31, 2021 at 5:29 am
Hi Eric. I have a 2011 Dodge Caliber Mainstreet. I have code p0301. It seems that my misfire is turning out to be a serious issue and I need some insight. I’m currently checking all the small things that I know of before replacing parts for cylinder 1. All spark plugs and coils are good. Fuel injector is not clogged, it is working properly and ohms match the manual. I looked at the intake valves through fuel injector port, they are clean. I do have carbon build up in the combustion chamber. Compression test performed on all cylinders shows high readings of 200 to 219 psi (Are high readings due to carbon build up?). Another thing I read is that sticky valves or bent valves could be an issue and I could check doing a paper test. The exhaust is making the paper pulsate rapidly and is being sucked into the pipe. Also I took the oil cap off while the engine was running and there is a loud chopper like sound with a lot of air being forced out of the oil port. I couldn’t find anything that explained what that means. I did find articles talking about blowby gasses but all said I should see white smoke. There is no white smoke coming out. Is my issue still classified as blowby gasses or do I have a different issue?
Jessica Gregory
November 20, 2020 at 3:59 pm
Dear Eric the car guy, I have a 2004 Toyota camry 4 cylinder so my spark plug blew out of my engine it was replaced 4 months prior to these. Should I try to fix it or do you think I should get a new engine? If thats the case ill sell it can’t afford a new engine.
Roberto
March 30, 2022 at 7:57 pm
Erick i have a 2008 Honda Accord that won’t go past 3000 rpms. Sometimes when cold it will trow misfire codes p301,!p302 and p302 or p0300 i eease them and codes won’t come back.
Jared
October 18, 2020 at 11:51 am
Hello @EricTheCarGuy,I am Jared from Kenya,I changed the Engine for my Subaru Lagacy,from then I got a real big problem…whenever I step on the gas,the car strain and just goes off,but as I disconnect the MAP sensor it pick to it’s maximum power.What might be the problem?.
Kelvin Exum
June 10, 2020 at 10:14 am
I have a 98 Lexus gs400. On the most part, my car runs quiet and smooth. Other times, it will have a bad idle. So bad at times that the check light will flash but later stay steady. I have gotten it checked to find out it is misfiring on one side of the engine.
Jim srack
July 16, 2020 at 5:22 pm
Hello Eric, your the Man. Ok here’s the situation Honda Element 2003 replaced Vetec solenoid, screen was clean in old part. Thought it was resolved, however the surge came back even at a lesser rpm before the surge than previously. What I don’t get is if the screen is clean whats causing the surging. Thank you in advance for your response