Diagnose and Fix Rough Car Idle - Main Causes For Shaking / Vibrating While at a Stop

Hi, I'm Josh, with a cheap mechanic. If you're watching this video, you're probably experiencing some car vibration issues, so you'd be at the traffic light, the steering wheel vibrates, the car shakes and hums and the rest. most of the time it works fine, there are many reasons why this can happen but I will show you the most common ones and also address some of the more obscure ones. Now if your check engine light is on you will want to start with that because it is I will tell you more specifically what your problem is either you have a code reader or you go to your local auto parts store that will read your check engine light. free form.

Start there if you don't have a check engine light it means you will need to

diagnose

. yourself, well, your most common problems will be your engine mounts, your spark plugs, your air system, and your fuel system. Now I understand that the air and fuel systems will have many elements within that, but we will address some solutions to fix all the custom solutions. In addition to chasing down the common culprits, the first thing is that the engine mounts are held in place by three or four points. They are supposed to be made of rubber that isolate vibration from the car engine and when they wear out they don't.

It doesn't work as well, so every car will be a little different, but generally you'll have engine mounts on both sides and the front and back of the engine and you'll be able to check them out individually, which I'll show you in a second, but if you want to have a general idea of ​​how your engine mounts are working and if they are working, you get an assistant and you put it in gear, you put it in gear with the brake on and when you put it in gear, you look at the engine with the hood open and see if It leans back and forth, it shouldn't move much and if there is a lot of movement with the motor in general you will know your mounts are getting old so the movement on this motor seems pretty normal but I'm going to move on. and checking individual brackets for signs of wear so frequently that one of the easiest ends to see is the passenger side.

What you are looking for is the rubber area. This is solid rubber and will start to crack. Big chunks can fall off and essentially just break off and then metal starts hitting metal so you want to check to see if there are areas that are between the engine and the car that they are hitting but this one looks pretty good here's the which is at the front of the engine. On this car again, this center section is all rubber and what will happen is it will fall off and the engine mount will fall off and the metal will start rubbing on metal.

It looks good, so again depending on your car mounts they will be in slightly different places. but on four cylinders there is often one under the air box and then you will have one behind the engine. Many times the transmission will have its own extra amount so keep an eye on that, plus if an engine mount is bad it creates a lot of stress. on the other brackets so they're probably about to go too if you're going to work on them, usually the bolts are pretty big and pretty tight, it's probably best to have a breaker bar and some big sockets, the second thing It's spark plugs for the spark Spark plugs burn the fuel create the energy and if they are worn or contaminated they will surely make the engine run so you need to remove the spark plugs to check it and when you take it out you will be checking. for things like cylinder oil leaks that would contaminate a spark plug when you pull it out, you're looking for the burnt electrode, too big a gap, too small a gap, just if the thing looks corroded and old, cars too.

They are meant to change your spark plugs at a set mileage so if you don't know when we are done with yours or it's time to change them they are really cheap and it really helps to just put a new set in and eliminate that problem because a flare actually can't be failing or breaking down without any physical science. Third, your air system, so your air system is what brings in the air and mixes it with the fuel in the correct ratio to make your engine run smoothly and efficiently if the system. starts to leak or get dirty or contaminated, it can cause your car to start running

rough

, so when you look at your air system, you know that air comes in th

rough

the air filter, but then it's basically distributed throughout everything. place of your engine, so The reason a vacuum leak would cause your engine to run poorly is because air enters where the system doesn't expect it to, so this is all controlled by sensors and if the air enters through a strange place, it will waste the fuel mixture. usually through rubber hoses you can physically see them which is the most common way to find them or sometimes if they are really bad you can hear a hissing noise

while

the engine is running you can hear a hissing noise and that might help you to track it. down, this is a big problem area, a lot of times you're going to have cracks around these flexible joints, any air hose, which is going to be these guys hear a lot of things coming into your manifold, you check the joints where they connect and you're just looking for hoses collapsed, obviously a crack divides your evaporation system usually is back here by the inlet, which can cause

shaking

and vibration if a hole is made there, depending on your engine;

You may have a lot of vacuum lines running behind your intake, so you just want to remember to check things behind the engine, so obviously there will be a lot of things that are not vacuum lines or air lines, like the intake hoses. refrigerant, big and small, but if you don't know the differences, just write. to double check everything, so that in addition to having vacuum leaks or air leaks in the hoses, you may also have them anywhere in the system, such as the gasket surfaces in the throttle body or in the intake manifold, and you can't necessarily see them.

One trick is to get a carburetor cleaner and

while

the car is running, spray it on and it will actually change the engine

idle

when there is a leak and suck up that carburetor cleaner so you can locate leaks there. period, so if I'm spraying this and suddenly get a drop or spike in my

idle

I know I might have a vacuum leak area, it just doesn't work for really small leaks but can be a good general start. Keep in mind that in addition to leaks, your air system can also become contaminated and basically dirt from water and oil can get in and ruin the different components of the system and cause the engine to run poorly.

We will do a kind of general cleaning of everything. air system using a throttle body cleaner or a carb cleaner, so what you want to do is come in here and remove this

main

hose from the air box. Some cars may not let you run with this completely disconnected because the sensors are going crazy, so you may have to put the hose almost all the way back and leave a small slit for your cleaner straw to enter, also read the can you are using carefully, there are many different products that do this and they may have sprays directly onto the throttle body so you take the hose off at this end and the car will probably try to die when you spray it so have someone there to press the accelerator and keep the car alive during the The spray will also be important, just be aware that the check engine light may come on because you disrupted the system and are ruining relationships, but don't worry, always You can reset it later and the car will run.

Well, we're going to run the engine and spray this continuously for about 10 minutes or half a can, something like that, and have the engine burn that stuff off and hopefully clean out all the gunk that's going to be on our airlines. be on our throttle body, etc., so a couple more air system items that I haven't talked about yet: your air filter in this air box and your mass air flow sensor which is usually in the air box or right at the head of this inlet. tube and those you don't want to run that throttle cleaner through, so we spray it on the hose after this, there's a special cleaner for that mass air flow sensor.

First you must open the air box and remove the filter. That's not terrible, if it's really dirty it can affect the idle, but that would be pretty unlikely, so since you already disconnected the hose here, you want to disconnect the mass air flow sensor so you can see that sensor through. There are different styles of mass air flow sensors, but essentially all you need to know is don't stick anything in there, don't touch it, and don't spray anything in there except mass air flow sensor cleaner because there are really fragile wires. and the electronics sometimes and essentially you're just going to spray this on and let it dry, put it back together, so if that didn't help, another big problem area is the throttle body, you want to make sure it's cleaned well, so I've We took the throttle body apart, you can see it's actually still pretty stuck together even after we applied the spray, so the

main

thing when working with throttle bodies is that you don't want to push the throttle head with your fingers, you don't want to move it . that on newer cars that are electronically controlled by the throttle, you will mess up the computer if you move it by hand, so ideally on these electronically controlled throttle bodies you want someone inside the cabin to turn the key and sometimes Press the accelerator to open it. throttle body up so you can get a carb cleaner all the way through and clean that area right where the throttle body touches is often the trouble spot and you want to make sure it's really clean so if cleaning the throttle body didn't make a difference There are other air system items that can be cleaned and their gaskets replaced, such as the intake manifold and idle air control valve, but those can be deep repairs and aren't that common, so before we get into that, Let's move on to the next most common cause of rough idling.

Fourth, your fuel system, like the air system, fuel is mixed with air in the correct ratio to get your car running properly again if it becomes contaminated or if something goes where it shouldn't. is going to work properly, so what happens to your fuel system? Over time, bad gasoline or ethanol and gasoline will gum up the entire system and as I mentioned before, that air fuel mixture gets thrown away and the wrong amount of fuel gets into your engine and that will cause rough running, lack of fuel economy, etc., so what you want to do is get a bottle of fuel system cleaner.

There are many brands, many of them work very well. You just want to follow the directions very closely, but you're essentially putting this in your gas. tank and goes through the entire system and burns off all that dirt and buildup that's in the valves and injectors and fuel lines and hopefully that fixes the idling problem so let's try the fuel system cleaners. . It will take a tank or two of gas before you start to feel the results and you just have to follow the instructions on this meerschaum very well. It says to add two ounces for every gallon of gas.

I know I have about eight gallons in this. auto, so I'm going to put in sixteen ounces, that's a full can, so the most common

causes

of rough idling in your fuel system are going to be your injectors and maybe even your valves. You can go in and remove the injectors. Clean them very well. You can use a more aggressive valve cleaner that you would spray into the intake just like we did with the air system, but they are a little more complicated so you should definitely start with that fuel additive first because it doesn't require any disassembly.

If you have addressed all of these issues and are still experiencing the same symptoms, there are other

causes

, some of them are easy to

diagnose

, some not so much, another way to get vibrations at low rpm is with belts. So your timing belt, your accessory belts, if they become loose or damaged, they can start moving if the tensioner

stop

s maintaining a constant pressure and starts moving, the engine will jerk that way. You can see what this idler wheel looks like here. not jumping up and down like in a stable, another possibility is on the harmonic balancer or on the crankshaft pulley, at the bottom there is a rubber or bushing integrated into the pulley and it is designed to eliminate vibrations so you can go down there. and you can inspect the crankshaft pulley and if it has that rubber ring on the inside, you can look for cracks, look for pitting, look to see if it's breaking and that may be one of the reasons why the last things I want to mention are possible, but they are quite rare. and are not something you can probably handle on your own without specialized equipment, such as things like your torque converter and valvesblown transmission or even a computer problem with your car, those will be the things you want to take care of. to a mechanic, so if nothing we've done so far has helped, it's probably time to suck it up.

I hope this video was helpful, thanks for watching and if you haven't already, please subscribe.