My Supercharged Miata Is Already Broken? No Boost

hello everyone and welcome it wouldn't be a proper project car if there weren't some headaches along the way so in this video we're gonna be talking about my Miata which has a supercharger however it doesn't always have boost now if you haven't yet checked out my video on the install you should definitely check out that video and overall the supercharger install itself went great so looking at it it's an extremely clean appearance honestly the first time you just glanced at this engine bay you don't even notice that it's supercharged it's a very clean install however the unfortunate news is that it's not making any more power depending on the scenario so first off to illustrate the problem I took my V box and I did some acceleration runs before and after installing a supercharger to see how much quicker the car would get and so I did pulls in first second and third to see you know what was the acceleration beforehand and what was it afterwards not including gear shifts all just in each individual gear what was the acceleration and so for example for first gear the average of a few runs from 10 miles per hour to 30 miles per hour was 1.8 seconds in second gear naturally aspirated before the supercharger went on accelerating from 20 miles per hour to 40 miles per hour happened in 2.4 seconds on average so then I put the supercharger on and I went out and did these same tests again the first run I did in first gear 10 to 30 miles per hour was 1.9 seconds so 0.1 second slower than when it was naturally aspirated I then did a pull in second gear from 20 miles per hour to 40 miles per hour and it did that in 2.3 seconds so 0.1 second faster then naturally aspirated that didn't seem right so I ran another second gear pull from 20 to 40 and this time it took 4.1 seconds much slower than when it was naturally aspirated okay so clearly there's a problem so this video was supposed to be the story of how much power my supercharged Miata makes and how the acceleration has changed and how joyful it is to drive and yet here we are again with me shifting in my garage so in this video we're gonna be figuring out what's wrong with my Miata and fixing it now starting off with the first time I drove the car there were already a few issues that were immediately apparent first of all was low speed throttle control and I knew about this before even putting the supercharger in there's plenty of discussion in the Miata forums talking about the low speed throttle control with this kit and basically how it is is that it's very sensitive to your right foot as you're going on the throttle and letting out that clutch and so clutch engagement especially in first gear as you're taking off it's very difficult to modulate it can be done well but it's very challenging and requires very sensitive use of your right foot so I wasn't too worried about that because everyone talks about the fab 9 tune out there that fixes this issue no worries it's a tuning problem I'm not worried about it the next issue I found was from the drive home from Humble mechanics shop and so on the way back using cruise control what I notice is that if you started to go up hill and you're in sixth gear cruise control it would keep going in and out of boost and so you get this jolting of the car because it's accelerating and then saying no we don't need that much power accelerating then saying no we don't need that much power and so you could feel the jolting and it just goes on off on off and it's pretty annoying in cruise control and so if I turn cruise control off and just use my foot to modulate the throttle well then the issue didn't exist anymore and you can easily modulate the throttle stay at whatever rpm you needed to be and you wouldn't have that jolting of that bypass valve closing and opening and giving you boost no boost boost no boost so again this felt like a throttle issue so I wasn't too concerned because it seemed like a software problem not a hardware problem now we get to the bigger issue of not having any boost so I was reading through Miata forums looking for other people that were experiencing this literally not having any boost and I was having trouble finding anyone that was having a similar problem so that's when I started to think okay there's probably a mechanical issue here and so I was trying to figure out a way that I could repeat not having any boost and then certain scenarios where it would have boost and what I found is that if I floored at below 4000 rpm in third fourth gear then it would have boost all the way to redline but if I already had it up to maybe 4000 rpm or above and I floored it then I would never get boost all the way to redline and so I was able to repeat that below 4000 I'd get boost after 4000 if I floored it I wouldn't get any boost so why does it have boost sometimes and not others and I think here's where a lot of people like to rush to judgement point fingers and say you did something wrong this company did something wrong and create this pointless blame game and it's it's extremely unwise to rush to judgment when you don't know absolutely everything about a scenario and it can make you look quite silly when you're wrong so I would urge you not to play the blame game and instead just focus on what's the problem how do I fix it so what I did is I took a laptop and I plugged it into my car and I read some data from the car to figure out what was going on and what I found is at 30 650 rpm when I floored it I'd see the manifold pressure jumped to about point 8 bar and then as it built boost it would go all the way up to about 1.6 bar well when I Florida at 4800 rpm what I saw as manifold pressure peaked up 2.7 bar and then it just simply declined from there and it never built boost and in both of these scenarios flooring it at 30 650 and flooring it at 4800 accelerator pedal position was at 100% so what's happening well here's what I initially thought and I was wrong by the way so here we're looking at the supercharger the air is coming in through the throttle body it travels then through the roots tile rotors of the supercharger and then into the engine now you have a bypass valve right here and there's a vacuum line attached to that bypass valve so when it sees atmospheric pressure the bypass valve closes and it forces a seal between this side of the supercharger rotors and this side so you create boost going towards your engine now what I thought was going wrong is that right here this valve wasn't fully closing and so my accelerator pedal position was at a hundred percent so this was wide open but then this wouldn't fully close so it was acting as a restriction as the airflow passed through and tried to go into the engine and because it was restricted and I didn't get a high enough pressure here there wasn't enough pressure to then close the valve and thus I couldn't get any boost so I called Edelbrock to try and figure out what was going on and they believed it was one of two things either it was the bypass valve somehow binding up or perhaps there was a problem with the actuator for the bypass valve so they told me to look over a few things on the car but unfortunately if everything looked good sounds like I'm going to have to send in the entire unit so they can check it over and make sure it's not a faulty supercharger obviously that was pretty disappointing to hear because it meant my car was gonna be out of commission for a while as the supercharger got looked over not to mention it's not the world's easiest task to take this supercharger in and out so I looked over the car and I found two pinched hoses one of which was for the evap line the other of which was for the brake booster now my brakes worked just fine and the brake booster line wasn't actually pinched too bad so clearly that one was still working regardless I fixed that I fixed the evap line so that it wasn't pinched but none of these should really alter with the bypass valve so then I took a borescope and I followed the line for the bypass valve to make sure that hose didn't have any kinks or pinches in it and that hose was completely clear from one end to the other again this does illustrate why it's important not to play the blame game because we did actually install these two hoses wrong they should have gone down and then across rather than just straight across which is why they were pinching now I wanted to verify the bypass valve was actually working and so what I did is I lifted up the car this thing's pretty difficult to access so I duct-taped my phone to the steering column and then started the engine and what you can see is the bypass valve is completely closed it's against its stop and then as you start the car and you create a vacuum within that intake manifold well then that bypass valve opens up and then I put the car in fourth year again it's lifted up it's just sitting there stationary and I floored it in four and so you don't have a bunch of load but you've got the wheels in the air spinning and so you can see briefly as I floor it and forth that bypass valve starts to close and then once I let off then it opens back up and then as I turn the car off well you can see the bypass valve once again closes once you have atmospheric pressure enter that intake manifold now I don't know what this bypass valve actuation is supposed to look like and in certain scenarios it did seem like its actuation was pretty slow so I'm still operating under the assumption that something is wrong with this bypass valve and so what I did is I reached out to fab 9 so fab 9 is a shop that has done a lot of work with these Edelbrock supercharger Miatas and they've got a lot of experience with them so I sent some of my data logs to them to have a peek at then I learned more bad news so my air/fuel ratios were a bit wonky and this was something that I was actually wondering based on my fuel economy and before you leap at me and say Jason of course the supercharged car is gonna get bad fuel economy hold on for a second hear me out funeral economy is a function of how much power you're making and how efficiently you're making that power so this thing isn't making all that much power on a relative scale you know around 200 horsepower at the wheels so I wasn't expecting to see fuel economy numbers as low as I was and this is partially explained by the air fuel ratio so while the system was targeting under boost an air fuel ratio of about eleven point four to one what it was actually seeing was about eight to nine to one for the air fuel ratio sometimes as low as 7 to 1 for the air fuel ratio and so what does that mean well it's how much fuel you're injecting so stoichiometric the ideal air fuel ratio meaning you burn all of the fuel and all of the oxygen in that combustion chamber that's an air fuel ratio of 14 point 7 to 1 so when you're under boost you're gonna run rich for several reasons it helps prevent knock it helps you make a little bit more power and it keeps your combustion stable but you don't want to run too rich and that scenario you start to waste fuel and you start to eat up your catalytic converters so essentially what's happening when this thing is running a 7 to 1 air fuel ratio is it's like injecting one in the cylinder and burning all that fuel and then taking the same amount of fuel that bad injectors injecting and just dumping it in the exhaust and letting your catalytic converter deal with it which is not wise to do and it's obviously gonna be terrible for your catalytic converter one piece of good news as far as fuel economy is concerned on the drive down to humble mechanics shop I got 35 miles per gallon and on the drive back I got 31 miles per gallon so it actually is possible if that bypass valve remains open to get solid fuel economy even with the supercharger installed now again air/fuel ratios that's a tuning issue so I wasn't super concerned about it and this was the point where actually did those acceleration runs that I was talking about at the beginning of the video where I found that it was slower after putting the supercharger on than before and so I thought well there's no point in putting it on a dyno if I can't actually get boost I need to actually identify what the problem is before going to that step I went back and looked at the installation footage and putting this supercharger in was a challenge so you know the actuator for the bypass valve got bumped it's getting touched maybe it got bent in one of these scenarios also I hit myself in the eye with a zip tie so maybe I just wasn't seeing clearly where are i protecting and you know hold the end of a zip tie when you're cutting it so that's where I was at I was pretty much ready to give up at this point I figured there's a mechanical issue with a supercharger I'm gonna have to send it back into Edelbrock to get it fixed then it comes back the car's gonna be out of commission for a couple weeks wasn't really looking forward to that but I decided to get Bryan and fab nine one last call one of the interesting things that would happen is when I'm in fourth gear and I floor it Sam at 5,000 rpm and I floor it I don't get much acceleration and I was assuming that this was a result of the bypass valve acting as some form of a restriction and so the revs would slowly increase to maybe 6,000 rpm and then I'm flooring it accelerator pedal is a hundred percent and yet it's not accelerating it's just sitting there at about 6,000 rpm at whatever speed that is and so Bryan at fab 9 he asks me well what's your throttle position and what a beauty the obvious question which is so easy to go back and say Jason why didn't you look at that but I simply assumed that if my accelerator pedal was at a hundred percent well surely my throttle pedal was at a hundred percent and it was not I misunderstood bypass valves so I thought this could create a restriction in the system when really it cannot so these supercharger rotors right here are always trying to create boost and what happens is when your bypass valve is open you no longer have a seal between the top and the bottom so it takes that air and it just forces it back around and it recirculates and you're never able to make boost as long as both sides of this compressor are connected so when you close that bypass valve now you've sealed off the top section from the bottom section so when you force more air below you build boost and then you make more power so if you're not seeing atmospheric pressure in this entire system it has nothing to do with the bypass valve instead it is because your throttle is not fully opening so I took my computer and I plugged it back in to datalog and what did it show well when I floored it in fourth gear above 4000 rpm while the accelerator input was a hundred percent the actual throttle position was about 33 percent mind blowing moment so this explains why I couldn't get much acceleration in fourth year because that throttle pedal was acting as a restrictor and it also explains why I couldn't get any boost because the throttle pedal was preventing the bypass valve actuator to actually get enough pressure to close and without that bypass valve closing I don't get any boost now I don't know why it's doing this so I'm not going to speculate but to me accelerator pedal position at a hundred percent throttle pedal position at 33 percent that sounds like a tuning issue not a mechanical issue so in my mind we are back so fab 9 sent me a calibration file and I put it on my car and holy moly what a difference so not only is low-speed drivability greatly improved but also my throttle position now much more closely matches my accelerator pedal and so the no boost issues are gone whether I floor it at 3,000 rpm or 5,000 rpm I have boost and I can continually go through the gears and maintain boost as I shift so it is dramatically improved and I'm very happy with the tune that is now on the car the good news is it's fixed what I thought was a mechanical issue with the bypass valve ended up being a tuning issue with the throttle valve in certain scenarios now sometimes with these types of videos folks get mad and they say why are you showing us all of this nonsense get to the driving get to the dyno sessions there's two major points I kind of want to make here first of all this is not a project car channel this is intended to be an educational channel and occasionally project cars happen to be the tool in which to teach something and that was certainly the case here and so you know you you learn things when you don't understand things and you try to figure it out and I genuinely find as much joy you know diving through these data logs and trying to figure out what's going on with this car as I do actually driving it maybe that's because I'm broken but I think there's a lot of value in looking at when things go wrong and then trying to figure it out I don't think YouTube needs to be this platform where we all pretend you know we know everything and nothing's ever going wrong and so in these scenarios where something's wrong with my car and I don't understand it it's very revealing to me you know how much I still have to learn about cars and so I feel there's a lot of value in content like this it has been 13 days since this supercharger went on and only today has it actually started working properly so I am hugely appreciative to Brian at fab 9 I will include a link in the video description to his tune if you're interested in super charging a Miata and doing the similar thing or if you already have one of these supercharged metas and so next I will finally be getting into you know the dyno run before and after the acceleration pulls and a proper test drive now that the supercharger is in working order thank you all so much for watching if you have any questions or comments feel free to leave them below Oh

Channel: Engineering Explained

Views: 562,577

Rating: 4.9542923 out of 5

Keywords: mazda, mazda miata, mazda mx-5, nd miata, nd mx-5, 2020 mazda miata, 2016 mazda miata, supercharger, supercharged, supercharged mx-5, broken, car is broken, no boost, engineering explained, project car

Id: OKZSSHjLiy4

Length: 17min 44sec (1064 seconds)

Published: Wed Jul 08 2020