3 Mechanic Secrets I Have to Tell You Before I Retire

here i've got an easy repair anyone can do themselves in this case it's a 2017 kia forte the check engine light's coming on it isn't running right we'll open the hood but thank goodness the check engine light is on so rather than guess we'll use a computer i hooked it up to cars you can see it says pl 301 cylinder one misfire detected now unfortunately these po codes are what are called generic codes lots of things can make an engine misfire could be the spark plug could be the ignition coil could be the wiring could be the computer and just don't think it's ignition system you got a bad fuel injector that can make a car misfire gasket intake gasket head gasket on number one that can make it misfire but the absolute simplest thing to do is this first we'll take the stupid beauty cover off get it out of the way and here's the ignition coils one two three four now it says number one is misfiring so we're going to take that out you just unscrew it sometimes they're hard to get out so you wiggle them and unplug them in this case it's a dual system you have to make it harder than normal so you gotta click it up then squeeze it to get it off it won't come off if you don't push that up the number two ignition coil get that out wiggle it pull it off get the screwdriver unlock the tab there we go then we flip it over and squeeze it off it comes then we'll do a simple test we'll put number two in a number one hole and number one in the number two hole put the bolts back in gotta make sure they're lined up they gotta line up with their hole and get them snug and remember to plug them in this one plugs in here snap this one plugs in there we'll leave the top off it's just a stupid beauty cover then we'll just push reset on the scan tool and that resets it so there's no coats then we'll take it for a little drive well i draw it around the light came back on so that's good now we can check it so we'll plug the working end in again here we go see what it says here we go it's going to read it well it's got one code and the code is po301 miss far cylinder number one so it's not the coil because it's still not firing right well guess what now we're back to square one but at least we didn't waste any money we swapped the cause but the misfire stayed where it was originally so it's not the ignition coil so put the coils back take the other one off so we're gonna check the spark plug and lo and behold the spark plug is loose it's not in tight enough we're gonna check it out anyway it doesn't look bad but who knows since this one's loose we're gonna check them all and i'll probably replace them anyway take them all out see if any of them are loose too stick them in spark bug holes these are a little loose too and put it all back together and see what happens make sure i put them in the right hole this is the green one that's number one and now we're missing one there it is there's number two and we'll hook all the cables up one two those we didn't unhook and then we'll bolt them all back in all four of them we'll start her up again see what happens what's running good now so we'll take it for a road test and see what happens and now i'm back it's running fine no check engine light i did put in four new spark plugs the old ones had gotten loose but got 80 000 miles so i put in new spark plugs no more misfiring and you might wonder why did it only have a misfire on one cylinder and not all of them if the spark plugs were worn out well even though it's a machine things don't necessarily wear evenly in this case the number one spark plug got looser and wore more than the other spark plugs did but you're gonna change them change them all don't go through the trouble of guessing here and there change all four of them make sure they're nice and snug so they don't get loose again and it won't have misfires in this case just to misfire on one cylinder not on the others eventually you probably would have done them all but we want to fix cars so when you fix them fix them right if one's bad change them all to show you how to fix a car that isn't idling correctly this mercedes it's okay going down the road but when you come to a stop it's shaking wiggling too much you can tell it's not running right but it hasn't yet tripped the check engine light and being a professional mechanic i hooked my giant five thousand dollar scan tool up and found 56 different codes none of which are related to the engine idling they are anti-lock brake codes communications for the airbag codes lots of weird stuff but nothing that would make it run weird so we got to start from scratch here eileen is the most crucial part of your engine when it's working correctly because everything has to be perfect it can be off a bit when you're going fast and still run okay but when it's only it's got to be perfect you got to have the right amount of air the right amount of fuel and the right amount of ignition power to the spark plugs to make the engine ride so always start with the basics first thing we're going to check is the air filter take all this plastic stuff out of the way in this case it has two air filters one on each side and of course being a mercedes-benz it has to use one of these stupid fancy sockets in this case tp20 socket so you unscrew all the stupid bolts to hold it in place they got a little carried away here and off it comes and they're filthy so we're going to change them now this baby has two spark plugs per cylinder it's a v8 so it's got 16 spark plugs so let's check the spark plugs it's often near impossible to get these off so we'll have these pliers stick them in and wiggle them then we got one off they only use a spark plug socket all right see what they look like hard to get out they probably been in here a long time babies are in there finally and as we can see there's a lot of corrosion on it these babies have been in a long time so we're going to change them out now we got to do 16 of these things what a pain in the butt mercedes-benz under design ford tried that dual spark plug years ago and i gave up with it heck they even use that stuff in world war ii they may think they're high-tech but they're still pretty low-tech when it comes to a lot of things like that old school get them nice and snug they get up and then a little tub then you snap the wire back on sometimes it's hard to find there's not much working room huh there goes now to get to the rest of the spark plugs you gotta unbolt the coil pack here so you can reach them otherwise there's no working room so you unbolt all the coil packs and get them out of the way now of course once you've done the eight on the one side we got to do the eight on the other side this baby is a pain in the behind but at least it's exactly the same i finally got all the spark plugs in all 16 of them and the coil as long as we're here let's look around for any vacuum leaks this thing is 15 years old looking for cracked plastic parts you can see there's been cracked stuff that's been jb welded back on a lot of plastic stuff break on these old ones but we're looking for vacuum lines and stuff that might have cracks or the rubber that's leaking well i don't see any of this 97 degree heat i'm just gonna put the filters on start it up and see what happens filter just goes back in screws on this side line them up and bolt the stupid things back on awful long threads on these babies and this one is even dirtier than the other one then you slip the whole thing back on back where the air goes then slip the sides on one there one on this side and stick the rest of the super beauty cover on then we unlock it and start it up and here we go we come to a stop and it's idling smooth as silk all the shaking's gone so now you know how to stop a shaking car from doing the shimmy while you're idling one of the most annoying things is your car's running okay but you got to get it inspected and it fails to test when we plug in the old scan tool on any scan tool we'll read this even a 20 one it shows it's got po100 mass volume airflow a circuit and here's how that circuit works this is a mass airflow sensor inside it little electronic part it measures how many grams of air flow into the engine per second and then tells the computer how much fuel to send to the fuel injectors so the car runs perfectly so let's open the hood and find it here it is right here bolts on here snaps on here now if we look closely we'll see there's no frayed wiring or anything sometimes the wiring gets frayed sometimes that's the problem sometimes you can even clean them with mass airflow sensor cleaner you want to use just this because it leaves no residue but i've been working on these things for years and i know when it gets that particular coat on a nissan it's a problem in the circuit it's not dirt or anything it's not running rich or lean there's a problem in the circuit from my experience in these it's always the sensor itself is just wearing out now if you feel lucky you can take it out and cleaning i got a whole video on cleaning it make your car run better with a little spray cleaner you can watch that and once you feel real lucky but with this particular coat there's a problem in the circuit and from my experience there's only three things that can do that a bad sensor bad wiring or a bad main computer now i've looked at this wiring i don't see anything frayed and where it frays is always at the end where the sensor is i see them where they get brittle where they come apart i'm gonna unsnap it just to make sure it's not corroded and green though so we'll squeeze it and pull it off ah and let's look inside as you can see it's pretty well sealed with these seals everything's shining metal there's no corrosion there when we look inside here it's kind of dark it doesn't look bad but i gotta take it off and inspect it in the sun so i'll unscrew this that's this is all one piece we'll just unbolt the air filter box and pull the whole thing off out it comes now as you can see in the sunlight this is crystal clean not dirty no problem with that we're just going to replace it easy job just take the bolts off it's a lot easier doing this once you get it off the car all kinds of working room here even that one's kind of tight because that's in the way not typical take all those off and normally you got to measure which way it goes so you don't put it backwards it's got a little marker on here and it says airflow goes this way but in this case you don't have to worry because one end bolt on the other is different so you can't put this one on backwards a lot of them both ends are the same and you could put it in backwards you wouldn't run right but this it only bolts on one way so you don't have to worry with this design and here you want to use a new one rebuilt ones you never know this is brand new it's already got a new gasket just bolts on get all four bolts on and make sure they're all tight get them nice and snug you don't want any air leaking past it just flip it over and do the other side it's important that you have an airtight seal because this is all filtered air you don't want non-filtered air with dirt in that will ruin these things these are hot mass airflow sensors when you shut the car off it burns any impurities off these wires by getting them glowing red hot if you get any dirt on that it'll make it burn itself out just like if you touched the filament of a light bulb with your greasy hands it'd ruin it so make sure it's nice and tight then we put it back on first thing slip it over the rubber the one i slipped over with the air box in its place make all the snaps click realize there's one's up here too and one you can't even see on the other side but you'll hear it click when i hit it there then we just tighten up the clamp get it nice and tight you don't want air leak in there especially and while you're at it go to the other side follow it make sure everything's solid make sure that's all bolted on tight it is okay then we go back inside and what we do is with the scan tool hooked up we will turn the ignition key on so the key is on the idiot lights are on but the car is not running then we go to the cartridge and go back and what we want to do is erase codes so we'll go to diagnostic codes up here erase codes yes so we click yes guess we got to click it twice there then we enter turn key on with engine off enter now it's erasing the code you have to erase it because if you fix it eventually it will erase itself but they could take a while and this is instantaneous you can see now it says there's no codes but we don't trust anyone so we'll go back we'll go back to read codes and let's see what it says no codes found so now it's reset and now comes the easy boring part we just start it up and let it warm up we've reset it but cars have what's called a drive cycle and in order to pass the emissions test it has to go through the drive cycle so we're going to take it on a highway going 55 miles an hour or faster then drive it in town a little and see what happens what we're going to do here is we're going to go to special functions as we do special functions it's quite interesting we want the global ob2 and what we're going to is the drive cycle monitor and as you can see here there are one two three four five incomplete monitors so restart the car and we're gonna watch these now there's only four it's already reset one most vehicles it'll pass inspection that it has to have just one monitor incomplete there's four now but this is an old car it's a 98 and back in those days you're still allowed to have two incomplete so we just have to drive it until there's only two incompletes then we can get it inspected and as i said you gotta drive on the highway a while at 55 60 miles an hour so here we go and wouldn't you know it i got a road testing going fast here i am in a massive traffic jam in houston isn't that just typical just realize that sometimes it takes a while especially these older cars drive it and watch the monitors until it's down to two well now it's getting down there and hooray now it's down to two we can go back now as i said most modern cars when they're 2000 or newer you can only have one mil not ready to pass the test but this is a 98 so with two mills not ready it will pass the test okay now there's only two mills not ready that means this particular 198 will pass the test but we got to make sure one thing we're going to go back diagnostic codes here we go and pray it hasn't set any while we were driving so here goes nothing read codes no codes found that means it's going to pass the emissions test and we succeeded hurrah sometimes it's pretty easy job if you use your noggin so if you never want to miss another one of my new car repair videos remember to ring that bell [Music] you

Channel: Scotty Kilmer

Views: 1,395,621

Rating: 4.9137592 out of 5

Keywords: 5 minute crafts, auto repair, car, car advice, car diy, car hacks, car life hacks, car maintenance, car maintenance tips, car repair, car repairs, car tips, cars, diy, diy car repair, diy life hacks, diy projects, doing this, doing this will save you thousands in car repairs, expensive car repairs, expensive repairs, how to save thousands of dollars, life hack, life hacks, repair, save, save money, save you thousands, scotty kilmer, mechanic secrets, mechanic hacks

Id: AjCB5GPj-bg

Length: 15min 23sec (923 seconds)

Published: Sat Sep 26 2020