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Ryobi 7kW EFI generator

Posted: Mon Oct 07, 2019 8:35 am
by kevm14
https://www.homedepot.com/p/RYOBI-7-000 ... /303035840

This is cool. I immediately needed to find out how the EFI system worked because Ryobi advertised "automotive grade" EFI. I'm thinking....well then you must have an O2 sensor and I am not sure I can foresee this thing running in closed loop. Happily, I was wrong. Check this out:

https://manuals.ttigroupna.com/system/f ... 1.pdf?2017
The RYOBI™ EFI system is designed for optimal engine performance with improved fuel efficiency and lower emissions than a comparable carbureted machine. Fuel and spark functions are electronically controlled and engine operation continuously monitored during operation to maintain an ideal air/fuel ratio and best power. Electronic control is achieved through the use of a throttle body assembly, which combines electronics, sensors, and throttle body functionality into a single unit. The EFI system components connect to the throttle body assembly through the wire harness or high pressure line.

Fuel is routed from the tank to the fuel pump module. A directional fuel filter is positioned between the tank and the pump module to prevent damage or failure of the EFI components. The fuel pump module takes in fuel from the tank via gravity feeding and generates approximately 39 psi of fuel pressure to the high pressure line. This high pressure line then terminates at the fuel injector located on the throttle body assembly where it is electronically controlled.

Spark is generated by the inductive ignition coil. Charging and discharging is electronically controlled using energy from the battery to produce the spark. The ignition timing is dynamic during the operation of the engine and will vary based on operating conditions.

To allow electronic control of various functions, a crankshaft position sensor is used to monitor a pattern of teeth machined into the engine flywheel. These teeth are detected by the crankshaft position sensor and processed such that control based on angular engine events can be achieved. The pattern of teeth are all equally spaced with a single tooth removed to provide a reference point in the rotation.

Sensor data is essential to controlling the air/fuel mixture. Engine temperature is used for warm up and prevention of overheating. Precise control comes from the feedback of the oxygen sensor. This component provides rich or lean data used for managing the fuel injector. An integrated heater is used for fast transition from open loop to closed loop operation.

The central component of the system is the throttle body assembly, which is composed of an electronic control unit (ECU), fuel injector, temperature and pressure sensors, and mechanical throttle body. With connections to all other components of the system, the throttle body assembly enables precise control of the engine through software algorithms running on the ECU. Using a dual core micro-controller, these algorithms monitor the various sensors in the system and then control the fuel pump module, oxygen sensor heater, fuel injector, and ignition coil.

Integral to the throttle body assembly are multiple temperature and pressure sensors. These devices provide data necessary for consistent engine operation regardless of temperature and altitude. External sensors include engine temperature, crankshaft position, and oxygen sensors.

Operation of the engine begins with turning on the power switch. When turned on, a red MIL located on the throttle body ECU will turn on and off indicating power is on and the light is functional. A constant on of the light indicates a fault code is present and diagnostics are to be performed. With no active MIL, the engine can be started with the pull starter or the electric start. For electric start, the push button commands the engine to start through control by the EFI system. With electronic control of the starter relay, a controlled start is performed where the user is not required to hold the button during the cranking of the engine. A simple switch press creates a command to the EFI system that allows a consistent start of the engine. Start cycle will time out after 5 seconds if engine start is not detected. Once the engine is rotating, the EFI system will begin to control fuel and spark and result in the starting of the engine. A warming phase will occur once started. This warming of the engine is transparent to the operation and requires no special considerations such as a choke or other fuel enrichment controls found on a carbureted unit. After the warm up is completed, the EFI system will begin closed loop control of the air/fuel mixture using the oxygen sensor feedback. Closed loop operation may be briefly canceled during large engine transients such as when a large load is applied.

If any system faults are detected, the MIL will turn on indicating there is an issue with the system. These faults are stored in the ECU and can be retrieved using the EFI Diagnostic Kit. Depending on the fault, the engine may continue to run but have reduced performance and non-compliant emissions. Diagnostics and troubleshooting should be performed if the MIL is on. A qualified technician can access stored fault codes using a cable that plugs into the unit harness and a Windows-based computer. Contact RYOBI Customer Service for more detailed information.
Well I'd have to agree. Heated O2 sensor for closed loop fuel control, and it even describes going open loop upon transients, which is exactly how traditional EFI works (learning feedback is disabled until a steady load is resumed). I think I'd look hard at this if I was in the market for a 7kW unit in the future, at the $1,000 price point. Then again, I don't know how robust all of the components really are. It does appear that they went to GM TBI school and kept the system as simple as possible. But a couple cheap Chinese sensors/components and this thing could be a real pain down the road. Going further, you could certainly argue that the 25% fuel savings and easy operation is not really worth the additional risk of issues with the system. I don't know if that alone would sway me, at least until a very clear indication of reliability issues was available online. So far, I see nothing like that aside from typical DOA type situations which will always happen.

Re: Ryobi 7kW EFI generator

Posted: Mon Oct 07, 2019 12:43 pm
by kevm14
Oh man. There is a section about the laptop software including screenshots. This is too much. I can barely contain myself at all the parameters.
Ryobi 7kW EFI generator software screenshot.PNG
Normal people don't want to think about power outages. Other people think about power outages but don't want to think about their generator. I love thinking about my generator. Haha

Re: Ryobi 7kW EFI generator

Posted: Mon Oct 07, 2019 1:40 pm
by kevm14
Slowly reading through the manual reveals more excitement. We already learned it has a MIL with fault codes. But it actually uses OBD-II standard P-codes, 20 of them to be precise. This is hilarious.

I do like the computer spark control and all that stuff. It can go 9.3 hours on 6 gallons at 50% load (3500W). That seems pretty long to me but maybe it's fairly normal. I am pretty sure my steady state load is less than 3500W based on my various data points with my 4000W unit. During a long outage I could conceivably go from morning to evening on a single tank depending on load. Not sure if it would stretch that long at lower loads. Maybe not.

Re: Ryobi 7kW EFI generator

Posted: Mon Oct 07, 2019 6:43 pm
by bill25
Interesting. Saving 25% fuel is great considering that equates to how long you can go with fuel on hand before needing to go find a gas station.

I agree with not wanting to deal with a million problems with something that needs to just work in an emergency though.

Re: Ryobi 7kW EFI generator

Posted: Tue Oct 08, 2019 6:13 am
by kevm14
EFI is starting to be COTS even on small engines now. I don't think I have any inherent distrust in it and generally EFI has proven more reliable than carbs on automotive engines. That said, I really don't have any major heartburn for carbs on small engines. I find them simple, reliable and easy to repair if there are any issues.

But it's not as simple as carb vs fuel injection. On cars, what happened (more accurately) was, EFI vs a carb in an era of emissions compliance and controls, the EFI was the better overall solution. A single barrel carb from 1950 is a pretty simple device...probably about as complex as a typical small engine carb.