Normal Engine Vibrations – The NVH App

Hello, my name is John Kelly and this is the WeberAuto YouTube Channel. Today I am going to show you how to use the new NVH smartphone and tablet app to diagnose vibrations on vehicles. I have a previous video where I showed you how to go on a road test and determine what type of vibration the vehicle has, and there are basically, there are three types, or groups, of vibrations that a vehicle can have: One of them is Tire speed related vibrations, which is everything that spins the same speed as the tires of which there is a lot of things that do that. Another one is drive shaft speed related vibrations, driveshaft or propeller shaft, same thing, on rear-wheel drive and four-wheel-drive vehicles. And then we also have the third group is engine speed related vibrations, and I will show you how to diagnose those also using this app, right here in your stall of your shop, but you should have first gone on a vehicle road test, and like I said, there is a separate video I have produced that shows had to road test with the new NVH app. So I’m going to start with engine speed related vibrations, I have got a 2015 Ford Explorer right here and I am going to show you what is normal on engine vibrations, and what would be abnormal, and how to tell if the normal vibrations that all engines have are being transferred into the passenger compartment to where the driver of the vehicle might be feeling it. So to do that I am going to use an optional, you do not have to have this, but it’s optional, it is a Bluetooth data link connector adapter. It is part number BT1A from GoPoint Technology, and their website is gopointtech.com thats gopointtech.com, and you can purchase the BT1A Bluetooth Data Link adapter, this one works with Apple and with Android devices, and I said we will have an Android version of this later this summer, but what this Bluetooth interface does is it allows us to just plug into the vehicle, communicate with the engine control module, and get the exact engine rpm and if you are diagnosing an engine speed related vibration, if that is what you determined you had on your vehicle road test, then I would recommend that you get one of these. Current NVH app customers, there is a discount code in the app where you can get a discount off the cost of one of these off the website so, we are going we are going to plug this in now and start the engine and just let it idle and we will take a look at a few things about normal engine vibrations Alright, with the app of course, we have to tell the app what vehicle we are diagnosing, and so I’m going to select “Pick my Vehicle” to pick your vehicle in the app this is a Ford, so I will scroll down to Ford, 2015, Explorer, and we will add more model years, we are adding more model years and more vehicles every week to this app, but this is an all-wheel drive, 3.5 liter engine, so that is the very top option here, and the app already knows this is a 6-cylinder engine, it already knows what the front axle gear ratio is, what the rear axle gear ratio is, this is a crossover all-wheel drive vehicle, the only thing it does not know is what size tires are currently on this vehicle so we have to punch in the tire size, these have a 255 50 R 20 tire, and once w ha’ve punched in that tire size all we have to do is hit “Start” and it takes us to the “Vehicle View” screen. I want you to notice that with me just sitting here holding the smartphone there are no parts glowing red on the vehicle view screen, and if you recall from the previous two videos I have done on this app whenever they app detects a vibration those parts will glow red on the screen

so obviously I am not vibrating, I am going to set this on the radiator support of the vehicle here and see if it detects any vibrations, and if it detects any vibrations, it will glow red, now there is a sensitivity level adjustment in the settings, by default we have got hurt on a medium sensitivity level and you can turn that up or turn it down Now notice, of course, it is not giving us, it is not picking up any vibrations at all nothing is glowing red, but watch what happens when I set it on the engine, by the way, I have a cord connected to the iPhone so that I can record the screen as we go here, but I want you to notice as soon as I set it on the engine, on the engine cover, the engine starts glowing red in the NVH app, and that means that it is detecting an engine speed related vibration Now there are several different types of engine speed related vibrations, and this app gives us three different ways to view which type of vibration we have, so we are looking a “Vehicle View” first, which just tells us you have an engine speed vibration, the next item is the “Live Graph” so on the bottom center of the screen, if we click the “Live Graph” icon, now it will show us a bar graph of amplitude levels for the different types of vibrations that are on this vehicle Notice the E3, Engine 3, engine third-order vibration, that means there are three shakes per revolution of the crankshaft, this is a V-6 engines, so on a V-6 engine there are three Pistons on the powerstroke per revolution of the crankshaft, and it’s absolutely normal on an engine to have, on a V-6 engine, to have three shakes per revolution, those pulses from the power stroke of the engine, but if I bring that smart phone back over here to the radiator support it is gone, now why is it gone? Well it is gone because the engine motor mounts, the transmission mounts, the exhaust mounts, the body mounts, all of the mounts are doing their job, they’re they are responding as they should to dampen the amplitude levels of those normal engine vibrations. If you ever had a vibration that did not change when you went from the engine to a fender, or radiator support, or the driver’s seat, the steering wheel, the floor, the dash, then that means that there is a transfer path issue between the engine and wherever the vibration is being detected or felt by the driver of the vehicle So, that is that’s a pretty cool way of isolating whether or not you have got bad motor mounts, transmission mounts, exhaust mounts, etc. Now there’s another view, if I set this back on the engine, we can go to the “Live Data” tab, in the “Live Data” tab will give us the vibration frequencies or rpm, right now the app in the RPM mode, rather than Hertz (Hz) or shakes per second, so this is giving a shake per minute in it, and it color codes anything, anything that, any of the numbers that are green there are engine speed related, and noticing gives us our engine speed, our vehicle speed, our tire rpm, and in the results down below, we are getting a third order tire speed, I am sorry, a third order engine speed related vibration, which is exactly what we thought we would have. Okay, now, Lora, step on the brake and put it in reverse With a vehicle under a load sometimes you’ll get additional vibrations or even more amplitude from an existing vibration, lets see if that changes anything here, nope, we still the third, occasionally you’ll see a second order engine vibration, V-6

engines also have a second order vibration that might be load sensitive or torque sensitive. Alright let us go to a “Bar Graph”, there is our engine third, a tiny bit of an engine one every once in a while, and then back to our vehicle view screen. Alright put it back in park. Now I have had some comments of wanting to know how accurate this app is as far as measuring frequencies. so I am going to switch, I am going into the settings by clicking on the gear icon and if we go down to units of measurement, click on vibration frequency, and change from rpm to Hz, and we go back, let us now look at live data. we are getting approximately 29.7 Hz 30 Hz vibration as this engines shakes three times per revolution of the crankshaft, Well I have brought along a resonant reed tachometer, this is a really old school vibration analyzer, and all it does is shows us the vibration frequencies that it is detecting, and how hard the little reed shakes up and down is the amplitude level, so I want you to notice that it is vibrating, and let me zoom in closer here, scoot everything over So I want you see the reed, right here at 30 Hz, is shaking really bad, so this old-school vibration analyzer, or resonant reed tachometer is telling us that we have a 30 Hz vibration, obviously you can see on the NVH app screen that it is picking up a 29.7 Hz vibration also, when I had it laying here but its self, without me touching it, notice we have a little bit of a 20 Hz vibration there also, that is coming and going, and you’ll notice on the app that occasionally we get a second order engine vibration coming in, and 20 Hz would match second order vibration, because look at our engine speed right now, engine speed is 10 Hz, so 20 Hz would be two shakes per revolution, 30 Hz would be three shakes the revolution, so that is a verification of the accuracy of the app and these sensors inside of the smartphone. Alright this is on a v-6 engine and the next one I want to show you is the same thing but on a four-cylinder engine, so we will pause right here and pick up on a four cylinder. Okay we’ve got a four cylinder 2007 Dodge Caliber right here a four-cylinder engine also have normal vibrations, but those vibrations are only going to be two shakes per revolution since there are only two cylinders on the powerstroke per revolution of a four cylinder. So if I set the app, the phone with the app running, on the engine, we should pick up an engine vibration, so there it is glowing red, if we switch to the Bar Graph we should have a second order engine, the E2, notice the E2 is certainly there, if we move the phone to the radiator support, notice it is either gone, or it is there, but notice the amplitude level, the height of the bar graph is much much smaller, so four-cylinder engines are a

little more shaky, some of them are, than six cylinders or eight cylinder engines. This could have a transfer path problem to where a motor mount, transmission mount, exhaust mount, etcetera, is transferring some of those normal engine vibrations into the passenger compartment. If we go to “Live Data” view, we can see the frequencies and the amplitude levels, noyice the amplitude levels are just extremely low. Our engine speed right now is around 14 Hz, we just started it so it is slowly warming up, if I switch that back to rpm, 854 rpm Notice on the “Live Vehicle” view it is just barely pick up a vibration, so this this Caliber has some normal engine vibrations that are being transferred into the radiator support, which means they can also be transferred into the passenger compartment, so if you put this app in on the dash, or the floors, or the steering wheel and you pick up this same normal engine vibration, then something is wrong, gasoline engine vehicles should not have that happening, now diesels, on the other hand, you are always gonna feel a diesel shaking, however, the amplitude level should be greatly reduced, so if we look at this amplitude level, we are at 0.03 here on the radiator support, if we put a right on the engine itself, it goes way up, 0.6, 0.7, 0.8, 0.9 1.0, a really high amplitude level, so we are getting a significant decrease in the amplitude level as we go to the radiator support, so the motor mounts, trans mounts, exhaust mounts, they are doing some of their job, but still somewhere something is allowing that those engine vibrations to be transferred, and the help file has a big list of things that can cause these normal engine vibrations to be transferred, it is not just motor mounts and so on Alright now, we are as you can see looking at the Vehicle View screen, we are using the Bluetooth adapter on this to read engine rpm, but let me show you how this can still work without the Bluetooth adapter, if I go into settings and turn off the Bluetooth Data Link adapter, and after I turn off the estimated engine RPM, if I go back to our screen here, and we go to the Live Graph or the the Live Data screen we have the ability to manually input engine RPM. There is this slider right here, so notice as I move the slider all over to the right it goes clear up to 3,000 rpm, and as low as 400, and you can change the minimum and maximum values in the in the settings, but we were at about 700 or so rpm on the tachometer, let us set that on there, notice now, telling the app that we are at 700 rpm, we are still picking up that same vibration on the bar graph, if we go to the Vehicle View screen we are still picking up the same vibration The only difference here is now we had to manually tell the app what the engine rpm is rather than read it automatically through the Bluetooth data link connector, so that’s a cool feature, I said you don’t have to have the Bluetooth connector, but it sure makes it easier for engine speed related vibrations only, will have no impact at all on driveshaft speed related vibrations, or tire speed related vibrations, so here is a normal four-cylinder engine vibration, two shakes per revolution, high amplitude level, we move it over to the radiator support or somewhere inside the

passenger compartment, and the vibration is either totally gone, or significantly reduced, that is what we are looking for Alright now, let us take a look at a V-8 engine. Okay, our next vehicle is a V-8, so we looked at a 6-cylinder, a V-6, a 4-cylinder, and now we are at a V-8 We have a 2015 GMC Sierra pickup truck with 6.2 liter engine, it is sitting here idling at about 600 rpm, as you can see with blue words for engine speed, we are using the Bluetooth datalink connection, and this is a four-wheel-drive vehicle, so has a different vehicle powertrain there, if I set this on the engine as we have done on the 4-cylinder in the 6-cylinder, now notice the engine is glowing red in the NVH app indicating that there is some sort of engine vibration The app will automatically tell us, if we tell it to record the vibrational, tell us what type of an engine vibration it is, or we can go into the bar graph, the Live Graph, and notice it says it is an E4 vibration, engine fourth order, so this is an 8-cylinder engine, so it has 4 cylinders, basically just half the numbers, four cylinders per revolution on the powerstroke, notice it is a fairly low amplitude vibration, if we go to Live Data, we can see it tells us fourth-order engine vibration at a pretty low amplitude level, alright now, as we move this out to the radiator support let us go back to our Vehicle View, notice the engine is not by glowing red indicating a vibration on the radiator support or anywhere else, if we put it on the vehicle, there is nothing on the the bar graph, and there’s nothing in live data with a three-axis inputs from the internal sensor, if we go to turn off the Bluetooth datalink and turn off the estimated engine rpm, and we set our engine speed with our slider at approximately 600 rpm, now we moved back over to the engine, it may have slowed down just a little bit, let me move the RPM down, there we go, so a fourth-order engine showing up, if we go to the bar graph, fourth order engine, and you and if we go to our Vehicle View screen, the engine is vibrating, all without a Bluetooth input, so we can use Bluetooth or the manual rpm. slider to tell the app the engine rpm, and then it does the calculations based on the type of engine, and the number of cylinders, as to what is normal, and ther i’s a whole bunch more to that, and as I said there is a help file included in the app that tells you all about engine vibrations, which ones are normal, which ones are abnormal, why they are abnormal, and what to do about diagnosing and repairing those .Okay, that is a demonstration of diagnosing engine speed related vibrations as far as do they exist on the engine? Of course they do, and do they exist outside of the engine? Which normally they should not. As I said diesels, a lot of time will, but the amplitude level should be significantly lower Alright, thank you for watching