A Few of My Favorites

Alison, Newton, Mia. These are a few of my favorite things.

Singnificantly Less Contrast Than Usual

I've previously posted photographs illustrating the contrast between Mia and the much larger vehicles next to which she is occasionally parked. When I arrived at work today, I found much less contrast than is usually the case:

That's a 2005 Mazdaspeed Miata. Mechanically, the main difference between these cars---aside from the aftermarket parts that I've installed---are the somewhat heavier wheels on the '05. This car is clearly the Lava Orange color, which makes it very unusual; only about 500 of them were made.

Enjoy the Contrast, Yet Again

Usually Alison and I take Rex on our many, many trips to Home Despot. Sure, the CRX is the smallest of our 3 cars by most measures,* but it also has the most usable internal volume. Besides, since Rex is old and beaten, we aren't too worried about minor cosmetic abuse he might incur.

Recently, I stopped at the Despot on the way to work, which meant that I was driving Mia. This is the sight that awaited me when I exited the store:

I suppose I should expect that kind of contrast when I drive my wee little sports car on a weekday to the hardware store favored by contractors. What I didn't suspect, was my parking situation when I arrived at my workplace:

Have I mentioned that I work at a laboratory, not a construction site?

* Length, width, and mass, but probably not height.

The More I Learn

The more I learn about Mia, my Mazdaspeed Miata,* the more I regret buying her, rather than a third-generation (NC) MX-5. Of course, I long ago personified her and assigned her a gender, so I guess we're stuck with each other for a while.

* Not just Mia. All the MSMs.

P0097, A Miata Success Story

I must say my ScanGauge II OBD-code reader has paid for itself;  I've used it---in conjunction with the internet, of course---to solve another ECU-related issue with Mia, my Mazdaspeed Miata.

Over the last few days, the check-engine light began illuminating intermittantly, principally when acccelerating and turning simultaneously, as when pulliing away when you get the green turn arrow you've been waiting for.  The CEL has usually been accompanied by mild hesitation of the engine.  Today, Mia threw the code repeatedly.  Each time, the code was the same:  P0097.  After I got home, I went straight to Mazda-Speed.com, the forum dedicated to my exact car.  It turns out that P0098 means, to paraphrase, "intake-temperature-sensor voltage too low," and this code is frequently reported on the MSM.  It seems that the wiring to the intake-temp sensor rubs against the edge of the sensor housing anytime the engine moves, which can cut through the wiring's insulation, shorting of the signal.   That sounds like it could be what's going on, I thougt, and headed out to check under the hood.

Sure enough, the intake-temp sensor's housing is hexagonal, and its edge has a clean, 90-degree angle.  The sensors leads are insulated, but not physically protected from the housing against which they rest.  The signal line---I believe it was the signal, rather than the ground---was worn down to the conductor.  I wrapped each line in electrical tape, then wrapped the two lines together.  A quick spin in the car verified that I had indeed fixed the problem.  

It makes me happy to repair a twentysomthing-thousand-dollar* car with 10 cents worth of electrical tape.

* MSRP, not what I paid.

Return of the King

Alison's mother, Sharon, came to visit last weekend. She's here to attend Alison's graduation---this Wednesday, seriously Wednesday---and to help us renovate and redecorate the Gronddulbarn. Sharon arrived in Rex, who has been living with her in Naperville for a year and a half. I am, once again, in possession of two cars with a total seating capacity of 4. I can also once more refer to a Miata as my big car.

P2187, A Miata Success Story

Recently, Mia's check-engine light has been coming on intermittently. Thanks to my ScanGauge II, I've been able to read the code, P2187, and clear it to see under what circumstances it recurs. P2187, as the internet will tell you, is the OBD-II, code for "too lean at idle," or something to that effect. I poked around on Miata.net* and Mazda-Speed.com** and found that this code could result from a number of sources, including a bad manifold-air-pressure (MAP) sensor, a leak in the intake track, a bad oxygen sensor, and so on. We are still clearing out the garage in the Grondulbarn, so, as of this morning, I hadn't taken a close look in the engine bay to further diagnose the problem. In the last two days, I've also noticed, thanks to my boost/vacuum gauge,*** that the vacuum level at idle was about 10 inches of mercury, higher than the usual 20-ish. Finally, today, I observed that the car's maximum boost seemed to be around 6 pounds per square inch, instead of the normal 8.5. It was then, on the road, that I realized that there must be a leak in the intake, somewhere in or near the manifold. That would explain all three symptoms: Air leaking in at low load, when the gauge pressure was negative, would yield a lean condition and a too-low (in terms of absolute value) vacuum, while air leaking out at high load, when the turbo was spun up, would give too little net boost.

Unfortunately, I didn't---and still don't---know much about the vacuum systems of the car. At my first opportunity, I put the hood up and went right to the only vacuum line I knew of, the small-diameter line leading off the back of the intake manifold and going to the...something, where I had T'ed off a line to the sensor for my boost gauge. As luck would have it, the 3-inch line between the manifold and the T had several cracks! So, I drove to the nearest auto-parts store, bought a few feet of the right-sized vacuum line for a few bucks, and cut and installed the line using the leatherman that lives in my trunk. Et voila, everything returned to normal! I'm Brian with the overhead projector about my parking-lot repair, as I'm sure you can tell.

Anybody need some small-diameter vacuum line? I have plenty to spare.

* The largest online community dedicated to the Miata, which has great resources in the Garage section and also has one of the best-run automotive fora I've visited.

** A forum dedicated to the 5428 Mazdaspeed Miatas produced.

*** This gauge measures the pressure in the intake manifold, so it performs, I think, essentially the same function as the built-in MAP sensor, but instead of being wired to the car's computer, it has an analog display for the driver. Interestingly, the gauge's negative range (called vacuum) is marked mm Hg, and positive range (labeled boost) is marked in PSI. I guess those are the conventional units for these two measurements---at least in the hegemony of the Imperial System---but I think it's strange to use two different units to measure opposite signs of the same physical parameter.

AutoX Photos

On the off chance that you care, I've updated my recent post about autocross school with a few photos.

AutoX

Yesterday, I attended another SCCA autocross school. This one was the Level 2 school, which I've taken twice before.

I haven't autocrossed since last Autumn, so I was quite rusty. In fact, I was very frustrated with the lack of progress over the last time I took the class. I had trouble with the figure-8 drill, which is designed to teach the student to steer with the throttle, to direct the car with over- andundersteer. I felt OK with my performance on the slalom drill. The sample autocross course, which is about half the length of one you might find at a competition, gave me the most trouble. I had trouble equalling my previous best time of 36.4 seconds.  

I did reach an important conclusion, however. I tried shifting into third gear for the fastest part of the course, where I have previously been bouncing off the he rev limiter in second. You might think it's a no-brainer to upshift under circumstances like that, but downshifting in an autocross course can be time-consuming. I managed to fit the downshift into the next braking zone without too much loss of time. In fact, since I was shifting anyway, I went all the way down to first, to pull away from what was the slowest point on the course. The ensuing upshift to second wasn't too time-consuming and was probably compensated for by the superior acceleration in first. With this approach, I was able to post a few funs below 36 seconds. My best time was about 35.4, which is a substantial improvement for such a small course. Sadly, I can't say that my reduced time was due to improved skill---I was still struggling with car control---rather than tactics.

Here are some assorted notes about the cars and drivers in attendance at the school:

• The cars were fairly typical of autocross schools and autocrosses in general---at least based on my experience---except for the number of Miatas; there were 5 first- and second-generation MX-5s among the 16 student cars.
• The fastest car there was an Apex Blue S2000 CR, just like the one I reviewed recently. Its owner was not very skilled, but, in the hands of an instructor, I saw it post a time of 29.9 seconds. And that was on the stock tires.
• The second fastest car was a previous-generation STI. I saw its owner consistently post times of 32 seconds and change.
• I spent most of my course-working time---when I wasn't chasing cones, anyway---talking with the owner of a current-gen Mini Cooper S---that's the one with a turbocharger, front-mounted intercooler, and a nonfunctional hood scoop, not the one with the supercharger, top-mounted IC, and functional hood scoop. He had a lot of experience in his Boxter but was new to autocrossing with front-wheel-drive. He had R-compound on his Cooper andconsistently turned in times of 33.2 and 33.3 seconds. I think that's a pretty impressive performance for that vehicle.

I'm sure that's more than you wanted to read on this subject, I'm sure. Please return to whatever you where doing.

Update: I've added some photos taken by Danny Kao.

Car Specs

I'm sure no one cares about these specifications, but a recent discovery inspired me to collect the following specifications about the vehicles I've owned. Keep in mind that these numbers are quoted by the factory, so they may not be entirely accurate at the time of manufacture, and they probably were less accurate during my ownership of the car. (All power and torque values are measured at the crankshaft, not the wheels.)

Specifications of the Automobiles I've Owned

Year, Make, and Model	Curb Weight* (lb)	Power (BHP)	Torque (ft-lbs)	Power-Weight Ratio (BHP/ton)	Torque-Weight Ratio (ft-lb/ton)
1977 Datsun 280Z	2875	149	163	104	113
1980 Honda Prelude	2020	72	94	71	93
1991 Honda CRX	2103	92	89	87	85
2004 Mazda Mazdaspeed MX-5 Miata	2530	178	166	141	131

I should point out that the Miata is now about 40 pounds heavier (when wearing the stock wheels), because I added a 50-ish-pound rollbar and removed about 10 pounds of material from the car. Additionally the Miata probably puts out something like** 182 horsepower and 170 ft-lb now, since I'm getting about half a PSI more boost due to the larger intercooler.

Anyway, the discovery that prompted this post was the true weight of my old Z. I think, when I went looking for it before, I read the value for the 240Z: 2355 lb. (The 280 is 500 pounds heavier because of the larger engine, beefier bumpers, stronger structure to support the bumpers, thicker carpet, a heavier dashboard, and other, more minor changes.) This means that Mia is not the heaviest car I've ever had, as I previously claimed. That makes me feel better. However, I'll miss the looks people give me when I tell them my Miata is the largest car I've owned.

* Curb weight includes all necessary consumables, such as lubricant, coolant, and fuel.

** To make this calculation, I assumed power to be proportional to oxygen consumed, which should be proportional to intake-air pressure. The total pressure is the boost (about 8 PSI, stock) plus atmospheric pressure (about 14.7 PSI). That's all very rough, as is my assumption of a 0.5-PSI increase in boost.

Enjoy the Contrast, Again

Regular readers may remember when I posted a pair of photographs contrasting Mia with a neighbor's  F-150-based Ford Excursion.  Now I'd like to post another brace of pics, this time featuring a different neighbor's F-150.

Enjoy the contrast.

A Positive Experience

I've owned my Mazdaspeed Miata for 9 months now, and I still look forward to driving it everytime I get in the car.  I guess that's as positive a review of the vehicle as I can give.

I Need to Think BIG

Instead of mucking tweaking Mia with a larger intercooler and better brake pads, perhaps I should go whole-hog with a Flyin' Miata FM II conversion.  I mean, how can I argue with this dynamometer trace?

Intercoolah and Baby Teeth

While I was taking photos of Mia for my recent post on her new winter footwear, I took the opportunity to snap a picture of the new, larger intercooler I installed a couple of weeks ago.

Below is a photo of the new charge cooler in place.  You may note that it is offset to the starbord (passenger) side.

 

Below is a photo of a stock Mazdaspeed Miata for comparison.  This is not my Mia, but she looked exacly the same.  The stock unit is quite a bit smaller, and would be almost completely blocked from view by my front license plate, even with the plate folded at the top and bottom as it is.*

Incidentally, these photographs show that I've replaced the 2 stock "tow hooks"---really tie-down loops  or tie-down eyes**---with larger ones designed for Spec Miatas.  These hooks are the black hoops visible on either side of the car's "grill" in each photo.  The new parts have much larger holes and project a bit further forward, which should make them easier to see and reach in the event that I need to be towed off the side of the road or or---more likely--out of the gravel at a race track.

* I should point out that I remove the plate for track days and autocrossing, both to get better charge cooling from the intercooler and to get better engine cooling from the radiator.  Oh, and, for what it's worth, I folded the top and bottom of the plate to a 90 degrees using a sheet metal brake in the machine shop at work.  It's amazing how much stiffer the plate is now.

** The "tow hooks" are intended for tying the car down during transportation from the Hiroshima plant to the dealer.  They aren't really intended for towing, though they work reasonably well for that, being secured to the chassis with 3 large bolts, though my new ones should work better.  Some Miata enthusiats find them to be unattractive and remove them.  These same folks call these parts "baby teeth" because of their location in the Miata's "mouth" port and their eventual absence.

Beware Summer Tires

My Miata, Mia, has worn "summer" tires since I bought her. These tires provide good grip in warm weather, but when the air and road temperatures get down to 40 degrees Fahrenheit or less, the compound gets hard, and the grip fades. A lot. And if there is snow or ice on the road, these tires would likely lead me on some unplanned off-road excursions. Mia's so-called summer tires are, in truth, good for 3 seasons here in Maryland, not just the summer. Winter is another story. So, today I bolted on the winter wheels and tires I recently purchased.*

The tires are Dunlop SP Winter Sport M3 models in the 205/50R15 size. They are 10 mm narrower than the 215s summer tires, but it should be just about perfect for snow use. The tires are mounted on the famous** 949Racing 6UL wheels in the nickel finish and the 15x7.5+34 size. These wheels are the maximum width that Dunlop recommends for these tires; I bought wider-than-necessary wheels so that I would have the option of mounting wide---probably 225---R-compound tires on them later, if I wanted to make this car into a dedicated track toy.

You may have noticed that these wheels are much smaller in diameter---2 inches smaller---than the stock Mazdaspeed wheels. This change saves significant unsprung weight, which should improve the function of the suspension, but with the possible cost of increased transverse sidewall flex when turning. With the slightly narrower tires, I've cut the weight of each corner from 39.1 pounds down to 31.1. That's a huge weight savings.

Below is a photo of Mia with her new shoes. You can see that the outside diameter of the tires is a bit smaller, 8 mm in fact. That reduction sadly exacerbates theMia's unsightly wheel-well gap, and it should also affect the effective gearing slightly.

Below is a photo of the front left of the car, showing the pleasant nickel finish on the 6ULs. Also visible in this image are the decals I've added to the vehicle. They are, from front to back, a traffic cone (signifying autocross), Summit Point's Main Circuit, Thunderbolt Circuit at New Jersey Motorsports Park, and a "Christmas Tree" (representing drag racing). I purchased these decals from Levant Goken at TrackDecal.com, and I'd recommend that site to anyone looking for something like these.

This third photo shows one minor cosmetic benefit of the smaller wheels. With them mounted, my brake rotors don't seem comically undersized anymore.

* You might be wondering why I didn't simply put all-season tires on my wheels when I bought new rubber this spring. Well, all-season tires are, by nature, a compromise between warm- and cold-whether performance. By having separate 3-season and winter tires, I can have more-or-less maximum possible traction in any weather ranging from excruciatingly hot to light-ish snow. If we somehow get heavy snow here, I'm unlikely to be interested in hitting the roads, anyway. The downside to having separate setups is the additional cost associated with 2 sets of wheels and tires as well as the additional storage requirement.

** In Miata circles, at least. These wheels are designed specifically for small import cars with the 4x100 lug pattern, and they offer low weight and high strength at very modest prices. One of the guys in my club says it's foolish to buy anything else. They are also available in widths up to 9 inches, so they are quite popular with drivers of heavily modified Miatae.

That's not an Intercooler. THAT's an Intercooler.

I installed a new intercooler into Mia today, with help from the Chesapeake Area Roadsters club.  The new intercooler has a volume about 1.8 times that of the puny stock unit, so I hope to see substantially less heat soak and more consistent boost when driving the car hard.

Spheres are Good

OK, just one more post about the car, and I'll shut up.

After a few months of daily driving, some autocrossing, and a couple of track days, I decided I didn't like the shape of the stainless-steel shift knob I put on Mia in March. It was comfortable for a pistol grip, but I've found I prefer an overhand grip. So, I replaced the knob with a spherical one two inches in diameter. The new knob is stainless steel like the previous one, because I enjoy the texture and the way the knob acts as a haptic, analog transmission-temperature gauge.


After a few weeks of normal use and a couple more track days, I've decided I'm quite happy with the way the knob feels. I think it's fairly attractive, too.

Electronics Review: ScanGauge II

Several months ago, I installed a ScanGauge II in Mia. The ScanGauge interfaces with a vehicle's electronic control unit through the on-baord diagnostics port. It works with any vehicle with OBD II diagnostics, which includes most made since the late 1990s.

Because the ScanGauge has access to everything the ECU knows, it can display a large number of digital gauges, 4 at a time. These gauges can give the driver very valuable information. I normally have mine set to display water temperature,* intake-air temp, battery voltage, and instantaneous fuel economy, but the device will also display numerous other parameters.

The ScanGauge also offers the ability to read errors, or "codes," thrown by the computer. These codes are responsible for illuminating the mysterious check-engine light. The SGII also lets you clear these codes. I've used this feature precisely twice, both times to clear the same code resulting from transient overheating due to pushing the car hard on the autocross course or track on hot day. Given the moderate price of this device---160 dollars, shipped, from Amazon---I think it paid for itself with just those 2 uses.

Overall, I give the ScanGauge II 8.0 out of 10. I highly recommend it to any car enthusiast or any information junkie.

* The OEM water-temp gauge is only approximate on the late NA Miatas and all the NBs.

An Ten Uh

I've long been a critic of powered accessories in vehicles. Power windows, door locks, mirrors and such increase cost, add weight, consume power, and decrease reliability compared to their manual counterparts. Unfortunately, my Miata, Mia, came with "power everything," and it has caught up with me after only half a year of ownership. A few weeks ago, my power reacting antenna failed, and in the lowered position. This failure meant that I could only listen to CDs in the car. Fortunately, my desire to listen to new music and the NPR withdrawal I've been experiencing has motivated me to address the issue.


I could have tried to repair the motor, but I elected to replace the antenna with a fixed one, and I was glad I made that decision when I pulled out the trunk liner and saw how enormous the OEM antenna/motor assembly was. The photo above illustrates the size of this assembly, most of which is due to the motor.


The new antenna is one of the stubby kind that are so common today. It's not the tiny shark-fin style, but it still looks fairly sleek. It has an amplifier built in, to compensate for its short length, which means it must be tied into the car's 12-volt system. Fortunately, since the original antenna was powered, that operation wasn't difficult. Even with the amplifier, the new antenna only extends down into the car about as far as the red marks on the OEM model.


After the installation, I confirmed that the radio works again. It sounds fine, so I'm quite pleased with this minor modification.

When I set out to take these photos, I realized that I haven't documented a couple of other small changes I've made to the car. More on that soon.

Thunderbolt Part 2: Revenge of the Thunder

I added a few more photos to my recent post on high-speed driving at New Jersey Motorsports Park. So, if you are interested, please check out that post.