Converting A Porsche 944 To Run A MAF

December 2, 2022 by Lewin Day 26 Comments

Electronic fuel injection was a big leap forward for engine control. However, early implementations often left something to be desired. This was the case for [Rob] and his Porsche 944, which had relied on an old-fashioned mechanical air flow meter (AFM). He decided to replace this with a modern mass air flow (MAF) sensor instead, and documented the process online.

The output of the sensors was compared with a rig built using a vacuum cleaner to create air flow.

AFMs are often a target for replacement on old cars. They’re usually based on a flap that moves a potentiometer wiper across a carbon trace which wears out over the years. They can also present an air flow restriction in some cases, limiting performance. MAF sensors instead measure the amount of air flowing through with a hot wire. The amount of current required to maintain the temperature of the wire indicates the amount of air flowing through the sensor. They’re less restrictive and readily available as they’re used in many cars today.

To run a MAF in place of the AFM requires a circuit to emulate the AFM’s output. [Rob] used a STM32 Cortex-M0 to read the MAF, and then output the relevant voltage to the Porsche’s engine computer via PWM and a low pass filter. To figure out how to map the MAF’s output to match the AFM, [Rob] built a rig to blow air through both devices in series, and measuring their output on an oscilloscope. This data was used to program the STM32 to output the right emulated AFM voltage for the given MAF signal.

It’s a great piece of work from [Rob] that has his Porsche running happily on new parts. We’ve seen similar hacks done to other cars before, as well! Video after the break.

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The J1772 Hydra Helps You Charge Two EVs At Once

December 2, 2022 by Lewin Day 20 Comments

There are plenty of electric vehicle (EV) chargers out there that are underutilized. This is particularly common where older EVs are involved, where the cars may only be able to charge at a few kW despite the charger being capable of delivering more. [Nick Sayer] regularly found 6.6 kW chargers being used by vehicles that could only draw down 3.3 kW at his work. Thus, he built the J1772 Hydra as a nifty double-adapter to charge two cars at once.

The Hydra comes in two versions. One is a “splitter,” which is designed to be plugged into an existing J1772 AC charger. The other is a version designed for permanent installation to an AC power supply as an EV charger in its own right. Either way, both versions of the Hydra work the same way. In “shared” mode, the Hydra splits the available AC power equally between both cars connected to the charger. When one completes, the other gets full power. Alternatively, it can be set up in “sequential” mode, allowing one car to first charge, then the other. This is great when you have two cars to charge overnight and don’t want to wake up to shift the plugs around.

It’s a neat hack that could be useful if you’re running older EVs that rely on slower AC charging. We’ve seen other DIY EV chargers before, too. Expect hacking in these areas to become more commonplace as EVs grow in popularity.

EV Chargers Could Be A Serious Target For Hackers

November 28, 2022 by Lewin Day 56 Comments

Computers! They’re in everything these days. Everything from thermostats to fridges and even window blinds are now on the Internet, and that makes them all ripe for hacking.

Electric vehicle chargers are becoming a part of regular life. They too are connected devices, and thus pose a security risk if not designed and maintained properly. As with so many other devices on the Internet of Things, the truth is anything but.

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Amphibious Dragster Drives On Water

November 17, 2022 by Lewin Day No comments

Dragsters are typically about peak performance on a tarmac drag strip. [Engineering After Hours] took a different tack, though, building a radio-controlled amphibious dragster intended to cross small bodies of water.

The build is based on a Traxxas Raptor RC car. However, it’s been heavily reworked from a pickup-like design to become a dragster with a motor mounted in the rear. It’s also been fitted with a foam underbody to allow it to float when stationary. The rear tires have been replaced with 3D-printed versions with large paddles, which provide propulsion in the water.

Initial tests showed the car struggled to make progress in the water, as the paddle tires tended to drag the rear end deeper under water. The tiny dragster tires up front didn’t help it steer, in water either. Large foam discs were added to the front tires to enable them to act as better rudders.

Fitted with its water tires and foam floatation aids, the car can only drive slowly on land, but [Engineering After Hours] points out this is enough to call it amphibious. It does a better job at skittering around on water, and it was able to cross a local pond at low speed.

We’ve seen some other creative techniques for making amphibious vehicles, like these crazy star-shaped wheels. Video after the break.

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Lamp Flashing Module Is Perfect For Automotive Use

October 1, 2022 by Lewin Day 17 Comments

Modern cars tend to have quite advanced lighting systems, all integrated under the control of the car’s computer. Back in the day, though, things like brake lights and indicators were all done with analog electronics. If your classic car needs a good old-fashioned flasher module, you might find this build from [DIY Guy Chris] useful.

It’s an all-analog build, with no need for microcontrollers or other advanced modern contrivances. Instead, a little bipolar PNP transistor and a beefier NPN MOSFET as an oscillator, charging and discharging a capacitor to create the desired flashing behavior. Changing the size of the main capacitor changes the flash rate. The MOSFET is chosen as running 12 volt bulbs requires a decent amount of current. The design as drawn is intended to run up to eight typical automotive bulbs, such as you might find in indicator lamps. However, [Chris] demonstrates the circuit with just four.

Flasher circuits were in regular use well into the 1990s. The original Mazda Miata has a very similar circuit tucked up under the dashboard to run the turn signals. These circuits can be hard to find for old cars, so building your own may be a useful workaround if you’re finding parts hard to come by. Video after the break.

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Coils In The Road Could Charge EVs While Driving

August 17, 2022 by Lewin Day 131 Comments

One of the primary issues with EVs is that you need to pull over and stop to get a charge. If there isn’t a high-speed DC charger available, this can mean waiting for hours while your battery tops up.

It’s been the major bugbear of electric vehicles since they started hitting the road in real numbers. However, a new wireless charging setup could allow you to juice up on the go.

Electric Highways

Over the years, many proposals have been made to power or charge electric vehicles as they drive down the road. Many are similar to the way we commonly charge phones these days, using inductive power transfer via magnetic coils. The theory is simple. Power is delivered to coils in the roadway, and then picked up via induction by a coil on the moving vehicle.

Taking these ideas from concept into reality is difficult, though. When it comes to charging an electric vehicle, huge power levels are required, in the range of tens to hundreds of kilowatts. And, while a phone can sit neatly on top of a charging pad, EVs typically require a fair bit of ground clearance for safely navigating the road. Plus, since cars move at quite a rapid pace, an inductive charging system that could handle this dynamic condition would require huge numbers of coils buried repeatedly into the road bed. Continue reading “Coils In The Road Could Charge EVs While Driving” →

Probing CAN Bus For EV Battery Info

July 27, 2022 by Bryan Cockfield 8 Comments

The widespread adoption of the CAN bus (and OBD-II) in automobiles was largely a way of standardizing the maintenance of increasingly complicated engines and their needs to meet modern emissions standards. While that might sound a little dry on the surface, the existence and standardization of this communications bus in essentially all passenger vehicles for three decades has led to some interesting side effects, like it’s usage in this project to display some extra information about an electric car’s battery.

There’s not a ton of information about it, but it’s a great proof-of-concept of some of the things CAN opens up in vehicles. The build is based on a Citroën C-Zero (which is essentially just a re-badged Mitsubishi i-MiEV) and uses the information on the CAN bus to display specific information about the state of charge of the battery that isn’t otherwise shown on the car’s displays. It also includes a build of a new secondary display specifically for this purpose, and the build is sleek enough that it looks like a standard part of the car.

While there are certainly other (perhaps simpler) ways of interfacing with a CAN bus, this one uses off-the-shelf electronics like Arduino-compatible microcontrollers, is permanently installed, and has a custom case that we really like. If you’re just starting to sniff around your own vehicle’s CAN bus, there are some excellent tools available to check out.

Thanks to [James] for the tip!

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