Help with building your Speeduino, installing it, getting it to run etc.
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Always post the tune used to take the log also. We load them together to see what the data does against the tune parameters. Please.

What was your engine-off MAP kPa?
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By tristessa
Whoops, forgot to attach that in my excitement earlier. Attaching it now.

Engine-off MAP is just about 100kPa on the dial in TS, maybe a hair under. There's not much elevation here, I'm barely over 200 feet above sea level.
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By tristessa
I'm thinking the easier starts and happier running a few days ago were a fluke. The very next day with nothing changed on the tune, I had to fight like hell to get it started and keep it running enough to get warm enough to drive around the corner to the gas station. It had magically gone from 3/4 tank to almost empty overnight, I think it leaked back up the filler neck through a garden hose. :roll:

I've got half a mind to use what I've learned so far to start building a new tune from scratch, re-checking everything while I do so. Because something's clearly not right, and I don't know what or where.
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By tristessa
After a seven month break where other projects needed my time and attention more than this, I'm getting back in the saddle on this car. It's been hibernating with the battery disconnected & on a maintenance charger, filled the tank with fresh fuel + stabilizer and made sure to run it through the pump and TB/injector so everything should be good to go.

I gave up trying to find a Mercedes distributor to modify. Made an extended drive dog and shaved a small amount from the upper neck of the distributor body to adapt an aftermarket Vanagon 2.1 distributor to the Mercedes engine, seats securely and locks down when the clamp is tightened. It's an extremely dumb distributor, with no advance mechanisms and a 3-wire Hall-effect sensor. I'll be using that with the late Vanagon ignition module and coil, and letting Speedunio control the ignition timing instead of trying to use a fuel-only setup.

MAP sensor is connected to a dedicated port in the adapter plate between the TBI unit and the intake manifold, IAT and CLT sensors are in appropriate places, O2 sensor is in the exhaust pipe just below the cast iron manifold. Still need to make a heat shield to isolate the TB and air cleaner ducting from the manifold heat. Fuel pump works and outputs the proper pressure for the TBI unit, TPS is still there and working correctly, and I'm saying all of this more to refresh my own memory than anything else. :D

Going to wipe the Speedunio and start fresh with a new tune next week. Between the ignition/distributor change, having to get a new laptop after mine was stolen, it's probably best not to muddy the waters with what I'd done with the tune last year anyway. Glad I was able to find the paper I wrote the injector flow/volume specs on, find those figures was a PITA....
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By tristessa
...and spent a month laid up unwell with something I must have picked up during in Europe the first couple weeks of April so I'm just now actually finally making progress.

Wired the distributor and ignition module to to the Speeduino ECM, roughly set the distributor to where the rotor points to the #1 plug wire at TDC, could be TDC, could be a few degrees before/after TDC, still need to check and get that locked down. Also need to make a heat shield to help isolate the TB from the exhaust manifold.

Started from scratch with a new tune on the new computer, got it running OK-ish. Used the tool at to generate a spark table and imported that into my tune, runs better. Finally able to start driving the car with Speeduino and the new distributor -- up and down the street a few times, then around the corner to the gas station and took a long loop around the "block" coming home from there. Also ran to the grocery store just a little bit ago. Drive as well as it did with the stupid carburetor when the stupid carburetor was more or less working correctly, but need to work on the starting. This isn't the *best* log because it's just from one of the runs up and down the street in front of my house, but the tune is where things currently sit and it hasn't been touched since the log was made. Going to let it cool overnight and see how it drives in the morning.
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