Modern engine control musings and Fixing a Figaro

well if you haven't yet seen aging wheels videos on this I have in fact bought this weird little Japanese car and I have what I'm sure will be a very rambley video for you about a small problem it has which I am attempting to fix with this mass airflow sensor cleaner so I've been wanting to make some videos about the extent to which cars are computerized and have been for a very long time this is a 1991 so nearly 30 years old and it is pretty much just as computer-controlled as an engine would be today a few things are not the same for instance it has an actual cable operated throttle and stuff like that but this EC CS is actually what Nissan called the electronically controlled combustion system so this engine like pretty much all engines in the past 35 years is hard is mechanically a real engine but electronically there is controlled almost entirely electronically the ignition timing can be altered through that coil over there the distributor is basically really just well you can't see from this side but the distributor is basically just pointing the current from the coil to one of the spark plugs I might be wrong about that but I'm pretty sure that it can and advance the timing electronically via the computer and everything on here is controlled by a computer now what it the problem that it has it is that ever since I got it and Robert did not cause it so don't worry if you're watching this and that is it has a it is hard to start when it's room temperature cold if it's very cold like near freezing it seems to start okay but when it is room temperature cold which it is now it typically starts in stalls the other thing is that when it is running it under moderate throttle tends to have a bit of a surging you know the engine will be like run around and you know no big deal works fine but that obviously is a sign of a problem so one of the things that it might be is a dirty mass airflow sensor the starting issue is probably not that but the surgeon might be so what does a mass airflow sensor do what as I said the engine is computer-controlled a computer is monitoring everything that this engine is doing it is not at all like a lawn mower that just is entirely mechanical it is very much computer-controlled so the first thing oh and I should say like I said very rambley this is connect straws it's what you get why do we do this well because we need the fuel to burn exactly as precisely as we can for emissions control we're trying to knock down nitrous oxide emissions and to do that you want the fuel to be burning stoichiometrically how do you do that well you need to know exactly how much air has entered the engine and you want to monitor that after it's been burned through the use of oxygen sensors so the mass airflow sensor which I have removed is this thing let me take it out of the off the dashboard now these are extremely delicate devices those very thin wires are what it uses to determine how much air is flowing into the engine and I believe don't quote me on this because I haven't looked it up that all that all it is is there a couple of basically resistors that it can you focus on that a little better let me just trip hang on okay so there's a couple of resistors and they bake what I think it does is it just heats them up periodically and sees how quickly did it core it monitors the resistance to see how quickly it cools down essentially and it can calculate how much air is flowing past it and you'll see they're staggered a bit so I'm sure that helps it this is from what I have seen a very atypical mass airflow sensor especially because it is only partially in the in the air stream but anyway this sensor allows the computer to know exactly how much air in grams is entering the engine so that's why it's called mass airflow because it's the air in mass grams per second so where the sensor lives is in that little hole so the air filter is in there it's passed the air filter and it monitors how much air the engine is actually ingesting from there it will calculate how much fuel should be put into the engine so you've got the fuel injectors down here and it can control extremely precisely how much fuel is going into the engine on every single combustion event and then the final check is the oxygen sensors and those are in the exhaust and truthfully I do not know where they are on this car because I haven't looked it up and I think there might only be one and the exhaust the oxygen sensor serves basically as feedback to determine is the mass airflow sensor or is the math it's doing correct so the oxygen sensor will be going back and forth between rich and lean and the computer wants to see that it's feathering that just perfectly so that's surging it's getting could be a result of that feathering especially if the mass airflow sensor is incorrectly reporting something to the car they get dirty over time this car is 30 years old and while it looks pretty clean that's not all focused correctly there we go well it looks pretty clean there's really no way to know and you should by the way never touch that because it's extremely fragile I no idea where I could find a replacement but it is a hitachi part so i imagine it's not you know extraordinarily rare but who knows so what i want to do is i'm going to clean the mass airflow sensor and see if it will start without doing a start stall i don't expect this to fix that because while there it can cause starting issues on more modern cars i really don't think that's the starting issue with this car what it probably is let me get on the other side on the back of the throttle body this part is a known failure point on Figaro's and this is what they call the cold idle valve i want to say it's an idle air control valve and the computer may or may not have any control over this i honestly don't think it does but it there's a vacuum line going to it so maybe and this is essentially what allows it to control idle speed because on an old car like this this is the throttle right here so it's actually actuated by the gas pedal and the computer has no control over this so in order to control idle speed there's a little bit of a bypass in this valve and normally it would be called the idle air control valve I don't know if this operates the same way but this is a known problem which causes hard cold starts and the other thing is the idle speed of this car is really really high on a related note that's why I asked Robert to replace the engine coolant temperature sensor because I thought it might just think the engines cold all the time so let's replace that in case that's a problem but that was not the problem so nope no worries though the car is completely drivable and this is a very minor complaint but the reason why going back why I suspect the mass airflow sensor which again lives in that hole could be the problem is that the when I first picked up the car from Robert it had set the cam crank relation code when I first got the car that code was in it it was code 11 and I figured out I found a code sheet about what that meant and I was able to clear the codes now I basically had the codes cleared the entire time I've had the car and so that was my experience of normal when I picked it up from Robert it was driving better and had a lot more power than it typically does then I checked codes and saw that code 11 was in it again so I cleared the codes and then it was driving worse so my suspicion is in closed loop mode when it's actually monitoring the fuel one of the inputs of the computer is wrong because it doesn't it's not calculating the the fuel correctly and this is basically the first input it gets so this is faulty it could run like poop now on the other hand the problem could be the oxygen sensors or sensor if there's only one and I will be looking into replacing that if this doesn't solve my problem but you a spray can of mass airflow sensor cleaner his hole is cheaper and easier to find than an oxygen sensor for this car it's not hard to find it all I can get it from the Figaro shop but we're trying this first because it's easy so I really don't expect it to fix the start stall but it might fix that surging issue and we'll find out shortly so what I'm going to do now is I'm going to take the mass airflow sensor outside and use the cleaner on it and then I will reinstall it and we'll see if it starts without needing some intervention okay it is back that's where it lives I need to I forgot about this part the wire for it has a little bracket there that I got to sneak it in there and then bend it back as a really weird connector you have to remove that metal clip up to remove it and I don't know if you caught this but it was definitely removed before because there was some sort of a lubricant around the o-ring that I very much doubt was original because it's still you know soft but maybe who knows but anyway so that's reinstalled the thing I totally forgot to mention I was talking about computer controls is the last part which is the catalytic converter which is not controlled by the computer whatsoever but it does get rid of any unburnt fuel and helps clean the emissions further and part of why it needs to monitor the fuel is because you can destroy the catalytic converter if you are not careful and on this car even though it has all sorts of computer controls it does not have a check engine light the six morning lights are super dope the brake warning light seatbelts low oil pressure this is your rear window defogger switch and then low voltage this one is a very simple light and if it goes on you have a problem because this is the catalytic converter overheat light and if that comes on it will never go out until you replace the catalytic converter essentially because there's a little little thermal fuse that will basically short out when it gets too hot and that light will be on forever until you replace that fuse so this car does not have a check engine light the way you check codes on it it's really absurd over there in the kick panel on the passenger side if you can see those two little plugs you remove those and then on the bottom one there is a hole that you put in a screw driver and on the top there are two LEDs green and red and you turn the screw driver a certain way to get it to show you the codes and then they will blink green and red so two green blinks and five red blinks is code twenty five I might have that backwards it might be red first but so that's how you read the codes from it and then there's a certain way to clear it as well so that's how I read code eleven and then the other thing it's very rambley I know is that the cam sensor on this car because the other thing about these computer controls is that there are sensors which tell the computer exactly where the engine is so it can know in its rotation which piston is coming up for which part of the cycle down to very fine amounts and in this car the cam sensor for whatever reason is in the distributor so the cam sensor is in there which is really weird and if you if it goes bad you basically need a new distributor so that's annoying and when I had when I first researched code 11 which is very vague from the code sheet that I found it was basically like there could be an error between the cam and crank relationship or it could even mean that your distributor is not connected and I was like that sounds wrong so I unplugged the distributor and sure enough the car will not run without that signal so that's not what the problem is I suspect the code was set probably when Robert was doing all the work for me either taking the distributor cap off or the timing belt change but the time about change obviously is fine because it runs fine and like I said it had the code when I first got the car but I cleared it and it never came back to my knowledge so I don't know why that code appeared but this is where the cam sensor is for this car it's inside the distributor and in fact I don't know if it has a separate crank sensor I think it does but not sure but anyway that's what I mean is I would like to make some videos in the main probably not with this car because I can't connect a code scanner to it it's just a little too old but that just overview all of the various computer controls that are in a car because I think people don't they you hear a lot of people who are like oh they don't make cars like they used to and they think about oh there's so many electronics and cars these days and it's like well there have been since the 80s there's really you haven't had a truly mechanical car since probably the late 70s I would imagine even in the late 70s and she computers started to become a thing because they were getting cheap enough I don't know exactly the cutoff but definitely in the u.s. anything made from 96 or newer is gonna have an obd2 port and you can talk to it but since a this is older than 96 and B this is from Japan it has all sorts of weird standards that I have no clue what they might follow I do appreciate how you know a lot of these warning labels are in Japanese and stuff like that like that guy that's pretty neat this car is definitely a guilty pleasure nothing whatsoever that I need but it's been it's been a lot of fun and I really do enjoy having it but what I have to do right now is wait another 10 minutes before I start it because I just want to make sure all that stuff has evaporated off of the sensor and then I will bring you with me to start it but it might be about terrain so I will probably not bring you on a drive because also I won't be driving right away but I'm gonna wait another 10 minutes or so before I start it and we'll see if hopefully leave starting issue is gone I very much doubt it will be gone because like I said it's it's probably that guy that's a problem and what I will do is remove it and try to clean it before I buy a new one because a replacement is like 160 bucks and if I can clean it with brake clean or carburetor cleaner or something even if it only works for another year that'd be nice but it will also be nice to confirm that that is in fact the problem and then I also got to look through the shop manual to find out what should the idle speed be does the computer actually have control over it it should because it has air-conditioning but the other thing is a lot of cars of this vintage with an automatic and air conditioning have relatively high idle speeds anyway but like it idles at 1500 rpm which is a lot it does have a tiny little 987 cc engine but still that seems kind of high anyway I'll be back in a bit okay I've waited long enough and it is about to rain so definitely won't be going on a drive but I did want to show you because I don't think Robert showed this in the video look at the dome lights on this car I just love that next to the mirror oh hi there's my head see that's just a lovely touch I know I only I have a garage door down the back doors open but don't worry the tops down that's a joke I'm only gonna run it for briefly so let's see if it will start without complaining my guess is no nope that's still problems you got to give it some gas [Music] and the weird thing is once it clears its throat it's completely fine so now it's probably going to be okay and then raise up the RPM a bit [Music] yep I have no idea why it does that but it's running that's good alright it's not the other thing is the cars park neutral switch is a little messed up so I often have to put it in neutral to get it to start I'm wondering why the key won't come out that's why okay well bummer but like I said I really wasn't expecting that to fix it while I'm back and as you can probably hear it's hot and I have great news it fixed the surging problem it is there just a tiny little bit when you are on light throttle but in most cases there was no surging at all and it seems to be it seems to have more power there's one of the things that I've noticed that this car is it has horrible turbo lag and now it's much improved so we did it or we did something so the mass airflow sensor was indeed dirty enough to be causing somewhat of a performance issue whether or not it means anything else I don't know but certainly it was perfectly drivable is just now it's a little nicer and yeah that's about it for this video like I said I want to at some point make true main channel videos explaining all this stuff with a more modern car that I can plug in code scan or two and actually like using oscilloscope to show what the sensors are actually telling the computer with the computer scene and cool stuff like that but we'll do that in a bit for now though thanks for watching this silly video and this silly little car oh and by the way I'm aware the battery does not have a tie-down strap I'm sure some of you have just been cringing looking at that I will look into that at some point but right now it does not have a tie-down strap and also the battery terminal and the negative barely fits on there I don't know if that's because this is a weird or I don't know if that's because this is an American battery and they have bigger terminals or what but I'm aware of those things I know I'll fix it

Channel: Technology Connextras

Views: 95,166

Rating: 4.9603724 out of 5

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Id: afrWCNoJkjY

Length: 19min 32sec (1172 seconds)

Published: Sun Jul 12 2020