Sulfur yellow 76: Megasquirted with tbi

[Toehead]

I plan on updating this as I go

The bike is a 76 sulfur yellow with 20k on it. (Shown below after megasquirt installation)

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Intake manifold is custom, with a geo metro TBI

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Airtex fuel pump.

Microsquirt controller

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[Toehead]

Fuel return is a block I machined to replace the petcock. It draws through the reserve (My gas gauge works fine ) and returns through the ON

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Air cleaner and throttle body fit nicely under the new electronics tray

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I'll take some more pics soon! I had it idling well and spent some time yesterday cruising around. I runs very well, and the intake roar is very cool

Unfortunately the microsquirt computer is acting up. After my nice ride, I returned to the garage and it woudn't communicate over serial. Tried multiple computer (including native serial ports) and nothing works. I then proceeded to try to reflash it (I thought it might be corrupted) and bricked it (partial reflash). I'm dead in the water until I get it repaired to replaced. I suspect a hardware failure on the max3221 chip, as it didn't affect the running of the bike at all. Will keep you posted.

[ericheath]

You've been busy. Interesting fuel return line. Never would have thought of that one. Look forward to more reports.

[akolleth]

Very nice indeed!

[wingrider]

Keep the pictures coming! Looking at a Megasquirt myself for my 1200 project.

[socrace]

Nice work, especially the fuel return idea, and use of throttle body injectors. Too bad about the comms issue. I guess you checked the serial cable, seems like that would be more likely to fail than the internal chips.

[Toehead]

Thanks Guys!

Yes, I tried multiple USB-serial adapters, multiple computers, and a computer with a native serial port with the same results on all.

Matt @ DIY sent me an RMA number and it is on the way back to be repaired. Ill keep everybody updated!

At least the weather isn't good


Sorace, I am really interested to see your base VE table, as well as where in the table your bike typically idles.

[socrace]

I'm sure Matt at diyautotune can get it straightened out.
Just wondering: are you using the Metro's idle air control?
Here's the ve table I ran all last year, Idles at about 60 Kpa and 1,000 rpm:

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[Toehead]

OK... This is also where I idle. It seemed like that was pretty weak vacuum, but if you are the same I guess it's fine

For idle control, no I am not. The Metro uses a coolant-temperature actuated fast idle valve (it is a wax capsule mechanical valve). I didn't want to run coolant lines to the throttle body, so I removed this valve and blocked it off. Right now, I just adjusted the throttle stop to have a good idle speed when warm. Of course this means you need to nurse the throttle when cold.

However, I have a PWM air control valve that just arrived. One I get my idle VE really dialed in so that it is stable, I will back the the throttle stop off and use PWM air control to maintain idle. This way cold start should be as simple as hitting the start button: No nursing required!

[Toehead]

Here is the type of throttle body that I used. It has a built in fuel pressure regulator, TPS, vac ports for MAP, etc..

Make sure you get the connector for the injector. They are really hard to find.

[DaveyG]

Definitely going to follow this thread!

[Toehead]

Pwm idle control!

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[Toehead]

Matt @ DIY confirmed that the microsquirt has a bad board and is shipping me a new one under warranty (the units have a 1 year warranty). I'm excited to get back on the road...

[Toehead]

Got the board back and am back in business.

I'm currently having fuel pump issues: Even though my fuel tank is clean (when viewed with a flashlight), the fuel return seems to be powerwashing the inside of the tanks of every bit of crud that has accumulated since 1976. I keep clogging my fuel filters. This was not an issue with the relatively low flowrates of the carb pump.

[wingrider]

how much pressure is that fuel pump putting out?