Posts in Year 2019

Understanding the Torque and Horsepower Curves

How does one plot the torque and horsepower curves for a 1999 Miata ? In this blog post, we explain how to do that using some dynamometer or dyno data from someone else’s 99 Miata. I have not taken my Miata to a dyno yet but this should be enough for an example for your car or for any other car, as long as you have the data.

The rest of the data specific to a factory 1999 MX-5 Miata (base trim and 10th Anniversary Edition) can be taken from here, which I provide as miata99_data_power.csv for download and also shown in the table below.

Jump-starting the Porsche Boxster S

First I added 2 gallons of gasoline in the Boxster. Then I tried to start it with the key in the ignition.

The Boxster was completely dead. So probably the battery was dead and needed a jump-start.

The battery is in the front trunk and the trunk does not have a manual lever to open it, in the event that the battery is dead. The Boxster fuse box (Figure 1) has a special red terminal (Figure 3) for a spare battery to turn on just enough electronics in the car to pop the front trunk. Once the front trunk is popped, you can access the battery and jump-start the full car.

A Copart Experience - 2001 Porsche Boxster S

Randomly in July while getting bored at work I was surfing Copart, a salvage auction site, that I saw a Subaru BRZ that had some hail damage but looked fine otherwise. Getting excited, I registered on Copart and placed a bid on it for about $600, but I lost. Over time I kept losing bids on similar BRZ/FR-S cars and decided to expand my horizons. So I started bidding on Porsche Boxsters with minimal damage, raising my maximum bid limit to $1500. I ended up winning a 2001 Porsche Boxster S (Figures 1-5), with 142,000 miles, for $1400 which had a dent on the rear driver side (Figure 3a and 3b), a broken tail light and was in driving condition. Despite having a Miata that needed work, I took on another project — classic project car mistake 😊 !

First Autocross in the Miata

With great trepidation I took the Miata to my local SCCA club autocross event today. I was number 919 in the E-Street class (Figure 1) and ended up chatting with other E-Street racers and their Miata configurations. One of them had upgraded his Base trim 1999 NB Miata to the Performance Package trim by adding all the required Mazda components that would form that trim including a Limited Slip Differential. It is something I might consider in the future.

Car passed inspection!

The Miata successfully passed inspection today. It took me nearly a year (364 days) since the purchase date to get the inspection done. Changing the O2 sensors was technically easy but I did not have the confidence to do it a year ago. Now I do ! Cannot explain how happy I am today that whatever hard work I have put in to make the car inspection-worthy has worked out well without any serious hiccups.

Fixing the Parking Brake

The Miata’s hand brake (or e-brake or parking brake) did not keep the car still. The car would move anyway, so I used to keep it in gear when I parked it. It was time to fix the parking brake before I took the car to the DMV for getting the emissions inspection sticker later this week. Fixing the parking brake is quite easy, but it requires removal of the rear wheels.

Replacing Oxygen Sensors

Since I purchased the Miata it has had a check engine light (CEL) code P0140. One of the solutions among many is to replace the rear Oxygen (O2) sensor in this case. Having experienced bad O2 sensors in my truck in the past and looking at opinions on the web, I decided to replace both the sensors to be safe. My car is a California emissions car and the location of the O2 sensors are different from the rest of the USA (Federal) emissions versions of the same car.

Mounting the Painted Wheels

The wheels that I had painted almost two months ago finally had the Dunlop Direzza III tires mounted on them. I had gotten it done at a local Mavis Discount Tire store for about $70.

However, I did not get them to mount the wheels on the Miata so that I could learn to do it myself. The reason I waited this long to get the wheels on was that I wanted to replace the brake pads and also buy a portable 20V DeWalt high torque impact wrench for about $250. But today I decided that it was time to mount the wheels and drive the car in those performance tires. Good weather makes you do that !

Without an impact wrench, you can use a 21mm deep socket, a socket extension, a breaker bar, a ratchet and a torque wrench to do the work. You also need a jack and jack stands, but since I have a mid-rise lift I used that. It took me about 2 hours to do this as it was the first time.

Spark Plugs and Plug Wire Replacement

One of the relatively easy improvements to your engine’s performance besides an oil change is to replace the spark plugs and the plug wires which is what I did today.

The recommended spark plugs for the NB Miata are the NGK Iridium IX plugs as seen in Figure 1. I also decided to replace the plug wires with NGK blue plug wires, both of which I purchased from Rockauto.com.

For the 1999 NB Miata, which has a 4-cylinder engine we need 4 spark plugs (Figure 2).

Cleaning the Headlights

The Miata’s headlights were not as clear as I liked, so I decided to try to clean them with Meguiar’s headlight restoration kit (Figure 1), which I purchased at my local auto parts store.

Chris Fix has a video (and another) on how to clean up the headlights but I did not follow his method, and instead bought a restoration kit to see if it did the job. I think it did a decent job.

Oil Change in the Briggs And Stratton Engine

Before I fix the ignition problem on the Briggs and Stratton engine that I bought on a whim the other day, I needed to complete an oil change.

I looked at the Operating and Maintenance manual and it said I needed to use 590 mL of SAE 30 weight oil which I bought at my local auto parts store for about $7.

ECU Reverse Engineering Step 1 - Another ECU

As I mentioned in the previous post, I had been sent the 1995 ECU BPL9-18-881B by an online seller, so I ended up buying an ECU from a 1999 NB Miata with the model number BP5R-18-881. This ECU came in today, so I quickly opened it up to take some pictures and find datasheets.

ECU Reverse Engineering Step 1

Going down the rabbit hole towards understanding the ECU, that I had had bought a few days ago, led me to realize based on ECU model numbers that BPL9-18-881B is the ECU for a 1995 Miata rather than a 1999 (Miata.net forum reference). I was disappointed and reached out to the seller on Facebook who did say they will send me the 1999 version and it was an error on their part, but so far they have not fixed their error. I consider this a loss of $60. I decided to move on, however. I bought a 1999 ECU on eBay and it should arrive in a week or so. Meanwhile, I will continue with this 1995 ECU since it will be cool to build two test benches to understand the difference between the cars.

Miata ECU and Car Hacking

A few years ago I had purchased the Car Hacker’s Handbook (Figure 1) from No Starch Press as I was interested to see what that book taught. I work in software and did some reverse engineering for a few years, so with the current Miata project it made sense to learn some tricks of hacking the car software (or firmware).

First oil change

I purchased the Miata almost a year ago, and it was time to change the oil. Since I had never done it before, I expected it to take longer than normal as I would need to familiarize myself with the process. It was quite easy to drain the oil, but removing the installed oil filter took a long time and I struggled with it, but eventually got it off. This post describes step-by-step how to do it.

Antique Briggs And Stratton Engine

On a whim, I started looking at Briggs and Stratton engines on Craigslist this week, and ended up getting a great deal on an antique horizontal shaft 3HP engine made in around 1989 or 1990 for just $20. It was owned by a retiree before this and she was just getting rid of junk in the garage. The engine did not start at the time, and that plays well into my plan of disassembling and learning how the engine works and fixing it.

Painting the Wheels Red

The wheels I bought earlier were from different cars, and I wanted to paint them bright red to get a unique look on my silver Miata. It took about 12 hours of work spread across 3 days to get it done. In this post, I describe how to paint wheels at home for cheap.

Samurai Sword Shifter Knob installation

I saw a Samurai sword handle shifter on a friend’s JDM import and decided to get one for myself through eBay a few weeks ago. It arrived today from China and I installed it in 5 minutes.

Replacing the Air Filter

Changing an air filter in the Miata is really easy. Below in figures 1 and 2 you can see the two latches around the intake that need to be opened with a simple flip as see in Figure 3.

New Floormats

In keeping with our post on installing new pedals on the Miata, I had ordered new Better than Factory floor mats from Moss Miata which turned out to be quite nice looking and similar in design to the original Miata mats from Mazda, as seen in Figure 1 below.

Tires for E-Street

In keeping with our post on wheels for E-street class for Autocross, I ordered Dunlop Direzza ZIII tires from TireRack.com with 200 treadwear and size 190/50R15 for my 15”x6” OEM wheels.

A mid-rise lift in my garage !

It is winter here, so I have not done any work on the Miata in January and February of 2019, but I did continue doing research and looking for the right tools. And lo and behold, I found a car enthusiast, who had 11 cars , who was selling his mid-rise lift on Craigslist for under a $1000 with delivery – a great deal !!! I cannot say I have been more excited to purchase a tool this useful.

Wheels for E-Street

The racing season is starting soon and since I want to stick to the stock E-street SCCA class for Autocross with this Miata, I decided to start with the least amount of changes I need to do to make the car competitive enough, but also let me focus on becoming a better driver.