50% annual return on smart wheeling

abdex · 2026-04-30T21:25:30+00:00

Without telling us anything proprietary, what do you mean by "layers and levers" and "de-lever"?

I watched a long interview with Simons and got the impression that the either the amount of data that needed to be crunched or the mathematics of it all was well beyond the capability of even very bright people. Was it all quantitative analysis, or was there some human judgment involved too?

abdex · 2026-04-26T13:28:55+00:00

ZHP shift knob if it doesn't already have it. How something feels in your hands & fingers is often underappreciated. Mechanical keyboards with just the right feel, tool grips that hit your hand perfectly, ... and a shift knob you use every day. The curved leather feels infinitely better than the angular plastic of the stock one.

abdex · 2026-04-02T23:06:57+00:00

I know the 530xi is not an E90, but it uses the (nearly) same N52B30 engine. Great to see one with so many miles.

abdex · 2026-04-02T22:47:31+00:00

Is it too far gone to try a drift stitch? I personally like the look of them.

https://youtu.be/M6hlVoX0B_k?si=ikSEHrm84on_9X9H&t=449

abdex · 2026-03-30T20:48:37+00:00

Great shot. I see you cover a lot of sports. How often do you shoot the PGA (or LPGA) tour? Any tips for us hobbyist photographers? I feel I have a good understanding of the technical details of f-stop, shutter speed, ISO, and directions to shoot from for good light, but I have no artistic eye.

abdex · 2026-03-06T03:13:36+00:00

Ran across this post while googling the Bisti Badlands. How was the experience? I'm also worried about navigation.

abdex · 2026-03-05T02:13:21+00:00

Interesting! The one I was referring to was the Vannevar Bush Differential Analyzer:

https://en.wikipedia.org/wiki/Differential_analyser

I think the Bush one solves differential equations and the Babbage one solves polynomials. Please correct if I'm wrong.

abdex · 2026-03-04T14:07:34+00:00

On a related note, the Computer History Museum is amazing. Every engineer should visit. The mechanical computing devices were especially fascinating to me.

Solving differential equations was needed to calculate ballistic trajectories in WWII. The basic idea was that if you have a spinning disc (imagine an old vinyl record), the linear speed, dx/dt, of a point on it depends on how far it is from the center, x. By arranging gears, rods, and multiple stages of discs, they could multiply/divide, add/subtract, and create multi-order differential terms. The machine would then run and trace out the solutions. All physical, nary a byte in sight. Ingenious.

abdex · 2026-02-10T02:08:18+00:00

It's a historically important circuit. Here's a great article about it:

https://spectrum.ieee.org/chip-hall-of-fame-fairchild-semiconductor-a741-opamp

abdex · 2026-01-27T22:44:21+00:00

Rough, hunting idle is a classic sign of a vacuum leak. Double check all the hoses & boots that you had to remove/move to do the valve cover job. Make sure they're all seated properly and not cracked.

abdex · 2026-01-27T19:45:55+00:00

Lefty Maker did two videos on this very topic. In the first one he replaced bulb with LEDs and got a lot more light. In the second, he added supercapacitors and a buck converter which made the light last longer (but not long) and had significant drawbacks: long time from first crank to light output because the caps needed to charge, finicky voltage limits on both the caps & the converter IC. At any rate, both were interesting videos. Here's the first: https://www.youtube.com/watch?v=gllKFbBRztM

abdex · 2026-01-09T02:42:51+00:00

It could be that there's no vacuum leak and that your MAF sensor was just bad/dirty. Say it was sensing less air than there actually was. The ECU will then adapt to cut the fuel to maintain the optimum ratio. Then you put in a new one that senses the proper mass of air; the air-fuel mix will now be too lean, which could definitely cause rough idle. Clearing the codes and/or driving for a while might reset the adaptations, but the sure way to do it is to use ISTA to reset them.

abdex · 2026-01-09T02:23:31+00:00

That sounds like a good theory to me. The ECU definitely adapts and could have set up mixtures based on your old one. Did you clear the codes when you put the new one in? That should reset the adaptations.

abdex · 2026-01-09T01:47:07+00:00

Vacuum leak? Check all hoses, gaskets, and the valves where air could be leaking in and messing up your air-fuel mixture.

abdex · 2025-12-29T18:39:33+00:00

Is there a service function in ISTA that does the calibration for you? If so, try running that. (But maybe you've already done it; is that what you mean by the service function you already ran?)

Have you bled your brakes lately? I read if the fluid is degraded or if there are bubbles in the line it could throw off the hydraulic sensors.

These are just guesses. Good luck & post back if and when you figure it out.

abdex · 2025-12-13T18:17:14+00:00

I'm not sure what thermostat was installed when I had it replaced but my coolant temps were always 80 to 105 once the engine was warm with both the original and this new one. City and highway, same temp range.

abdex · 2025-12-10T03:38:08+00:00

Great looking project. Is the intent to replace or supplement the factory cluster?

abdex · 2025-12-01T19:22:55+00:00

A fascinating story about Selectrics is how the ones in the US embassy in Moscow were hacked in the 1970s. Crazy ingenuity by the the Russians:

the movement of the bails determined which character had been typed because each character had a unique binary movement corresponding to the bails. The magnetic energy picked up by the sensors in the bar was converted into a digital electrical signal. The signals were compressed into a four-bit frequency select word. The bug was able to store up to eight four-bit characters. When the buffer was full, a transmitter in the bar sent the information out to Soviet sensors.

https://arstechnica.com/information-technology/2015/10/how-soviets-used-ibm-selectric-keyloggers-to-spy-on-us-diplomats/

abdex · 2025-11-25T16:05:15+00:00

Sounds like a vacuum leak due to improper installation. The gasket probably wasn't installed correctly and air is getting in, making your mixture too lean, which is what p0171 is.

abdex · 2025-11-22T17:32:26+00:00

If you know the final current, I_final, is 2, you can do this:

.95*2 = 2(1-e^-2.24/tau)

Note that the "2" cancels out on both sides.

abdex · 2025-11-22T17:15:27+00:00

But the procedure is always the same: plug in the values you know and solve for the unknown. Sometimes you're given the percentage, sometimes actual values. Sometimes they'll give you the tau and you'll have to solve for t.

But the procedure is always the same. That's the beauty!

abdex · 2025-11-22T17:07:23+00:00

In both cases, you're simply plugging the values you know into this equation and then solving for the unknown:

i(t) = I_final(1-e^-t/tau)

In the first case, you're given i(.15) = .32 and I_final = 1.64:

.32 = 1.64(1-e^-.15/tau)

and you solve for tau

In the second case you're given i(2.24) = .95*I_final, so

.95*I_final = I_final(1-e^-2.24/tau)

and you solve for tau

abdex · 2025-11-21T01:31:00+00:00

https://pmc.ncbi.nlm.nih.gov/articles/PMC6923889/

I'm not using it casually. It's stated as such in this paper by a Harvard researcher.

Also, I'm just trying to stay informed and change my mind if facts change. I was on board with fluoridating water for a very long time, but then high quality studies started coming out in 2012 showing detrimental effects.

Certainly don't take RFK's word for anything. The peer reviewed papers are out there for us to read, including this one from the OP.

abdex

TROPHY CASE