The Case Of The Mysterious Driveline Noise

July 14, 2021 by Lewin Day 31 Comments

Spend enough time on the automotive classifieds and you’ll end up finding a deal that’s too good to pass up. The latest of these in one’s own case was a Mercedes-Benz sedan, just past its twentieth birthday and in surprisingly tidy condition. At less than $3,000, the 1998 E240 was too good to pass up and simply had to be seen.

The car in question. Clean bodywork is too tempting to resist, even if there are mechanical issues.

The car was clean, too clean for asking price. Of course, a test drive revealed the car had one major flaw – an annoying hum from the drivetrain that seemed to vary with speed. Overall though, mechanical problems are often cheaper and easier to fix than bodywork, so a gamble was taken on the German sedan. The first order of business was to diagnose and rectify the issue.

Characterise, Research, Investigate

The first step to hunting down any noise is to characterise it as much as possible. In this case, the noise was most noticeable when the car was traveling at speeds from 40 km/h – 60 km/h, present as a vibrational humming noise. The location of the noise source was unclear. Importantly, the noise varied with the speed of the car, raising in pitch at higher speeds and dropping as speeds decreased. Engine speed had no effect on noise whatsoever, and the noise was present regardless of gear selected in the transmission, including neutral. Continue reading “The Case Of The Mysterious Driveline Noise” →

CAN Bus Wireless Hacking / Dev Board

July 11, 2021 by Chris Lott 5 Comments

[Voltlog] has been hacking away at the CAN bus console of his VW Golf for quite some time now. Presumably, for his projects, the available CAN bus interface boards are lacking in some ways, either technically and/or price. So [Voltlog] designed his own wireless CAN bus hacking and development module called the ESP32 CanLite (see the video below the break). The board was tailored to meet the needs of his project and he claims it is not a universal tool. Nevertheless we think many folks will find the features he selected for this module will be a good fit for their projects as well.

In his introduction of the design, he walks through the various design decisions he faced. As the project name suggests, he’s using the ESP32 as the main controller due to it’s wireless radios and built-in CAN controller. The board is powered from the car’s +12V power, so it uses a wide input range ( 4 to 40 V ) switching regulator. One feature he added was the ability to switch automotive accessories using the ST VN750PC, a nifty high-side driver in an SO-8 package with integrated safety provisions.

The project is published as open source and the files can be pulled from his GitHub repository. We noticed the debug connector labeled VOLTLINK on the schematic, and found his description of this custom interface interesting. Basically, he was not satisfied with the quality and performance of the various USB-to-serial adapters on the market and decided to make his own. Could this be a common theme among [Voltlog]’s projects?

A word of warning if you want to build the ESP32 CanLite yourself. While [Voltlog] had intentionally selected parts that were common and easy to purchase when the project began, several key chips have since become nearly impossible to obtain these days due to the global parts shortage issue (it’s even out of stock on his Tindie page).

If you want to dig deeper into CAN bus hacking, check out this talk that we wrote about back in 2016. Do you have any favorite CAN bus development boards and/or tools? Let us know in the comments below.

Continue reading “CAN Bus Wireless Hacking / Dev Board” →

Custom Car Horn Makes Many Sounds

July 9, 2021 by Lewin Day 29 Comments

A regular car horn is fine, but lacks finesse for more subtle communication. For example, some car horns aren’t particularly adept at short indicatory honks, and can only blare loudly regardless of the situation. For a fancier solution, [Tom Hammond] whipped up a custom car horn capable of playing a wide variety of sounds.

The system uses the Adafruit Audio FX board. This is a unique part, which is designed to enable people to build sound-based projects without the need for a microcontroller or any other similar hardware. Instead, the device can be connected to a computer over USB in mass storage mode, and its 16MB in-built memory can be loaded with sound files. It then plays these when buttons are pressed, hooked up to its 11 trigger inputs.

The Audio FX board has its output hooked up to a 120W amplifier, which then feeds into a pair of 15W PA-style horns. These are incredibly loud devices, though lack bass, so they’re really only good for throwing low-quality sound out in a noisy environment. For a car horn, that’s perfect.

The result is that [Tom] can press a number of buttons on his dash to play different sounds, from courtesy honks to animal noises and obnoxious sound effects. The great thing is that the sounds in question can be easily customized to the user’s tastes. [Tom] also deserves a tip of the hat for explaining in great detail how to actually install the project in the average car.

We don’t often see car horns around these parts, though they do make for an awfully loud alarm clock. If you’ve got your own nifty car accessories that you’re cooking up, be sure to drop us a line!

The Nuclear Powered Car From Ford

July 8, 2021 by Al Williams 42 Comments

We think of electric cars as a new invention, but even Thomas Edison had one. It isn’t so much that the idea is new, but the practical realization for normal consumer vehicles is pretty recent. Even in 1958, Ford wanted an electric car. But not just a regular electric car. The Ford Nucleon would carry a small nuclear reactor and get 5,000 miles without a fillup.

Of course, the car was never actually built. Making a reactor small and safe enough to power a passenger car is something we can’t do even today. The real problem, according to experts, is not building a reactor small enough but in dealing with all the heat produced.

Continue reading “The Nuclear Powered Car From Ford” →

Tech Hidden In Plain Sight: Cruise Control

July 8, 2021 by Al Williams 29 Comments

The advent of the microcontroller changed just about everything. Modern gadgets often have a screen-based interface that may hide dozens or hundreds of functions that would have been impractical and confusing to do with separate buttons and controls. It also colors our thinking of what is possible. Imagine if cars didn’t have cruise control and someone asked you if it were possible. Of course. Monitor the speed and control the gas using a PID algorithm. Piece of cake, right? Except cruise control has been around since at least 1948. So how did pre-microcontroller cruise control work? Sure, in your modern car it might work just like you think. But how have we had seventy-plus years of driving automation?

A Little History

A flyball governor from a US Navy training film.

Controlling the speed of an engine is actually not a very new idea. In the early 1900s, flyball governors originally designed for steam engines could maintain a set speed. The idea was that faster rotation caused the balls would spread out, closing the fuel or air valve while slower speeds would let the balls get closer together and send more fuel or air into the engine.

The inventor of the modern cruise control was Ralph Teetor, a prolific inventor who lost his sight as a child. Legend has it that he was a passenger in a car with his lawyer driving and grew annoyed that the car would slow down when the driver was talking and speed up when he was listening. That was invented in 1948 and improved upon over the next few years.

Continue reading “Tech Hidden In Plain Sight: Cruise Control” →

Electric Land Speed Racing Can Be Lightning Fast

July 8, 2021 by Lewin Day 4 Comments

Land speed racing is a pursuit of ultimate speed above all else. Most cars typically run on huge, flat salt pans, and racers run flat out for miles in a straight line, attempting to push their machines to the limit. Like most motorsports, the history of land speed racing has traditionally been centred around internal combustion, but electric racers have long been out there chasing land speed records as well.

The Need For Speed

At the most famous land speed trials, such as Bonneville’s Speed Week, speed runs take place over miles and miles of open salt, with timing traps along the way to determine competitor’s speeds. These tracks are long enough that acceleration is of little concern, which is of great benefit to electric runners. Additionally, only one or two runs is required to set a record. This means that heavy batteries aren’t always needed, as the distance a competitor must travel is short, and even if the batteries are heavy, it doesn’t excessively affect top speed.

With an eye to that, land speed competitors in electric classes are typically classified into weight classes. This is due to the fact that bigger, heavier battery packs can deliver more current, and thus potentially have a performance advantage over lighter vehicles. Thus, typical classes run by most salt flats competitions involve the E1 class, which allows for vehicles under 1100 lbs, the E2 class, for vehicles up to 2200 lbs, and the E3 class, which is for anything 2200 lbs and above. The FIA also publish their own set of classes, again separated by weight, though to a much more granular degree.

Procedures for setting records vary depending on the venue and the record in question. Local records at salt venues like El Mirage can typically be broken with a single run faster than the standing record, while Bonneville Speed Week competitors must set a higher average speed across two runs on two consecutive days. FIA records differ again, and are perhaps the most stringent, requiring competitors to set a faster average across two runs in opposite directions, set within an hour of each other, to attempt to minimise the effect of wind on the result. Things can sometimes get confusing, as many FIA records, for example, are set at the Bonneville salt flats, but not actually in Speed Week competition or by Speed Week rules. Continue reading “Electric Land Speed Racing Can Be Lightning Fast” →

Hacking Old Honda ECUs

July 3, 2021 by Chris Lott 21 Comments

Automotive security specialist by day [P1kachu] hacks his own cars as a hobby in his free time. He recently began to delve into the Engine Control Units (ECUs) of the two old Hondas that he uses to get around in Japan. Both the 1996 Integra and the 1993 Civic have similar engines but different ECU hardware. Making things more interesting; each one has a tuned EPROM, the Civic’s being of completely unknown origin.

[P1kachu] took his Civic to a shop to have some burned-out transistors replaced in the ECU, and a chance conversation with the proprietor [Tuner-san] sends him on a journey into the world of old EPROMs. [Tuner-san] pulled out an old PROM duplicator stashed away under the counter which he originally used as a kid to copy PROM chips from console games like the Famicom. These days he uses it to maintain a backup collection of old ECU chips from cars he has worked on. This tweaked [P1kachu]’s curiosity, and he wondered if he could obtain the contents of the Civic’s mysterious PROM. After a false start trying to use the serial port on the back of the PROM copier, he brute-forces it. A few minutes of Googling reveals the ASCII pinout of the 27C256 EPROM, and he whips out an Arduino Mega and wires it up to the chip and is off and running.

Advantest R4945A EPROM Duplicator c.1980s

He’s currently digging into the firmware, using IDA and a custom disassembler he wrote for the Mitsubishi M7700 family of MCUs. He started a GitHub repository for this effort, and eventually hopes to identify what has been tweaked on this mysterious ECU chip compared to factory stock. He also wants to perform a little tuning himself. We look forward to more updates as [P1kachu] posts the results of his reverse engineering efforts. We also recommend that you be like [P1kachu] and carry an Arduino, a breadboard, and some hookup wire with you at all times — you never know when they might come in handy. Be sure to checkout our articles about his old Subaru hacks from in 2018 if these kinds of projects interest you.