hey everybody it's about the mechanic again hey i'm here i'm around a little bit i got a bunch of stuff going on as usual in my life but a customer just dropped off last night and awesome is suzu trooper i'm trying to read while i'm talking it's a suzu trooper this uh ferrari i put head gaskets on it like about six months ago or eight months ago and it's back he said that it's uh it's missing out and uh so i told him drop it off last night man he dropped it off and so first thing this morning i got here and in the dog and of course fired up and it is missing well i wanted to show you guys kind of how you figure out what's missing and try and diagnose the problem when you don't have a computer and you don't have a scanner you don't have any of that i've talked about this in other little videos on how to diagnose some misfire but this is a good example you know like i haven't done anything to it yet you know i mean you can see i got some tools out but i really hadn't done so what we're going to do is i'm going to turn it on and we're going to listen and we're going to try and figure out what where that where the mist is coming from so here we go well maybe not maybe it won't start well we'll jump it off then we'll start okay so here we are man you're awesome susie trooper i don't even know what year it is what's it down let's see 96 90 second season they all sound like this i don't know why they all knock they all sound like every size i've almost ever seen from these gear models these 3.2 3.5 i think it's got something to do with the rods or something they just always take a lifter anyway as you can see right now we're just sitting here i just turned it on i jumped off of a damn battery the battery must be dead and they didn't charge it or something as you can kind of see the engine is kind of rocking it's doing this number right here which is your first clue that something's wrong it's not firing on all six cylinders because if it was it'd be balanced i don't know if you guys can see how much it's rocking it's not really you know that noticeable but i mean if you're sitting here watching it i can definitely tell so what i'm going to do is i'm going to start right off the bat this car's got coils coil packs okay it doesn't have spark plug wires but it would work the same way it did these are coil packs one two three there's three on this side and three on that side and if it was spark plug wires to do the same thing there'd be three spark plug wires going back to the center back here with a wire just like on any other car what you want to do is just start unplugging them see what happens let's try that when you're trying to plug one one of the coils see what happens now when i unplug when i unplug this coil what i want to hear is the engine change in rpm i want to hear it die down okay and that lets me know that i took the cylinder offline and it's no longer getting spark and gas exploding okay let's try it and see all right here we go you ready you can see where i'm at right here watch and listen you see that that was a huge change now i'll put it back a big change in rpm so we know that this cylinder is working 100 it's getting sparked and it's also giving fuel so we don't have to worry about this now we move on to the next cylinder which is right here and basically what we're gonna do is we're gonna go through all six i'm gonna go through i know this one's good i'm gonna go to this one and i'm gonna check it and see if it's good i'm gonna do this one and if all three work then i'm gonna jump to the other side because i know that all three of these cylinders have spark and fuel because it's changing the rpm and if it wasn't getting fuel or if it wasn't getting spark you'd have what's called a dead cylinder and that cylinder won't do anything it won't change the rpm at all you can unplug it all day long and it won't do anything so i'm going to try this really quick and then we'll come back hey i'm still here check it out okay so we're here on this isuzu i already checked all those three cylinders they were working fine all three of those cylinders on that bank on the passenger side they work great getting spark getting fuel now we're on the driver's side i already figured it out i don't know for sure what's going on but i know which cylinder it is that's you're definitely getting your way there okay watch this i just did the same thing that i told you guys it's hard to see but there's a coil i did it to that one and here's the coil i did it to that one and this back cylinder i did it to this one now watch what happens when i unplug it no change no change in noise at all so basically what this tells me is that this back cylinder something's going on with it that back cylinder is either not getting fuel or it's not getting sparked okay or somehow maybe the compression is completely off and it can't do anything but that's highly irregular cars will usually run any gasoline engine will run at about 100 psi if it's got 100 psi compression or above you're ready it'll work okay and that's why it's important you know you don't really need the scanner what you need is a brain and a lot of mechanics don't have a brain the compression gauge is a cheap thing you can go about harbor freight or any of these tool companies it might cost you ten dollars but the compression gauge will tell you how high your compression is on each cylinder and if you know if you've got over 100 psi you know it's going to fire off it might not run great but it's going to run like i said i mean that's a different note i'm pretty positive this thing's got good compression because i just put head gaskets on it not even you know a year ago so i'm sure that's not what it is so now the reason i tell you all this is now we're gonna have to figure out a does it not have fuel or b does it not have spark it's one of the two most likely 99 likely so what do i do you say man like oh do you just go buy a new coil buy a new spark plug buy a new injector you could do that you could just throw all those parts at it and see if it fixes it and probably one of them will but what i'm gonna do is because i'm a cheap bastard is i'm gonna take this spark the spark plug coil this whole coil i'm gonna take it off and i'm gonna put it on a known good cylinder such as one of these maybe i'll put it on this one okay i know that that cylinder was good and i know that this one isn't i don't know what's wrong with it something's wrong with it yeah so when i take this coil off and i put it on the good one and it still works what i've verified is that the coil is still working if the coil works here and i put it over there and it doesn't work something's going on either you're not getting a signal there or it's got an injector that's broken or something so we're trying to use deductive logic they call it in science class to try and figure out what's going on okay so that's what i'm going to do now i'm going to yank that coil off i'm going to put it on the other one and i'm going to come back and we'll see what happens right hola hey so uh here uh i checked it like i told you guys i was i swapped those two coils around right and no change okay so what that tells me is that i moved one coil that was not working to a known good spot that has a good signal and it changes and it works great on the other cylinder but it's not working in that same spot so i put a good coil in there and it still doesn't work so it leaves me with a couple options okay obviously the coil is still good because it's working the other side so either a it's not getting fuel from the fuel injector the fuel injector is not dumping fuel into the combustion chamber b it's not getting spark okay so it would be getting sparked that coil is good so i'm not getting a signal for spark okay and this is where it gets kind of shitty and people get really scared okay and i understand why so this is like a little bit more advanced than most people can handle okay but where i'm gonna go you know like i said i could take everything apart and switch the fuel injector and that's one option but i don't want to do that because it's hard and it's kind of like buried here in this engine underneath the intake plenum and that sucks so i don't want to do that right now another thing is i use my eyes you know like i use those eyes that your girlfriend that you don't use and i noticed right there there's a wire right here that somebody's with in the past okay and this wire is going down to that other side as you can see lookie there see that blue r it's going to here and this is like a transistor or whatever they're called module okay and so somebody in the past has wired directly into this damn thing and so what that tells me is there's probably a break in the wire somewhere to that injector well just so happens that's like number six or whatever and it just so happens number three on the other side's not working so you know just with deductive reasoning i'm thinking maybe i should just get an led light and check and see if i've got spark over there on that wire and if i don't i might have to wire one of these wires straight to that injector maybe somehow on the wiring harness is broken or a connector is broken or it's rusted out this truck's old you know this is one of those things where you got to kind of use your eyes and i'm not saying that's what it is but i'm just saying it could be what it is and that's just looking at this one's is already up so that one might be up so you know that's where i go from here i think that's what i'm going to try you might ask how am i going to do that well i don't have any fancy tools you know i do but i'm not going to use them here's what i got this is an led light that i stole out of some piece of machinery i don't even remember what it was it's probably like a stereo or something i don't even remember it's just straight up led light okay it's really simplistic if you connect it positive and negative it'll light up let's see well it's an led so it's not going to work that way because i have it backwards i wish i was that smart you can kind of see there it works so now this led doesn't use very much wattage so i'm going to turn the car on and i'm going to you know stick one of these in the negative obviously i guess this white's negative so i'll have to ground this out somewhere in the chassis and then i'm gonna stick this red line into that wiring harness and that coil wherever it is right there i'm gonna there's three wires in there so i'm gonna just start checking while the car is running i'm gonna check and see if i've got a blinking light usually what happens on these cars is that uh they're supplied voltage all the time that means they always have they've always got voltage and they're all they're looking for ground a ground signal and so that's usually how they switch these things and i think the injectors are the same way i think but i'm so i'm kind of gonna just play play with it and see i'm gonna see if i get any signal coming out i should have some type of blinking light in between a combination of those three wires and so if i don't get that which is kind of what i'm expecting that means i'm gonna have to you know check up here again on that thing this transistor thing module and if i do have it there then i'll have to run a wire but you know the purpose of this video like i said wasn't necessarily to show you guys how complicated all the stupid wiring is but what the purpose of the video is is to show you how you can diagnose this yourself it doesn't matter if you got a chevy pickup or an audi or a maserati or a lamborghini it doesn't matter dude okay all that matters is that like you observe you look at the car it's shaking it doesn't sound right it's missing it feels like it's missing when you drive it then you come out here and you start yanking spark plugs you can either yank the spark plug wires you know if you have an old chevy 350 you just got to be careful because it'll shock the crap out of you so you better use some pliers like this and some insulated gloves like that maybe or bigger gloves because an old chevy pickup will shock you so you just unplug one at a time and if you hear that cylinder die out then you know it was running good then you go to the next one and the next one and you try every single one until you figure out where the problem was and it might be this cylinder it might be the other cylinder who knows you know that's what you're using and then like i said the next thing you're going to do is kind of go down the logic path okay like all my spark plugs are working and it's firing well then you know it's not a spark you know maybe the carburetor's messed up or maybe whatever's up this is just how you do it you know this is the the mentality you need to have to try and figure out what's going on so let me do this now we'll check it out see if i can fix it