Megasquirt success

[joel.truher]

Hey everybody,

I thought you'd get a kick out of my injection project, finally done after many years of pecking away at it.

Engine, showing CB crank and cam sensors from years ago, LS coils, Dub Shop fuel rails, CSP linkage and Jenvey throttles, IAC valve on the extreme right with a Uni filter. The IAC doesn't have as much authority as I thought it would, still working on that.

Dashboard, showing Raspberry Pi running Tuner Studio, etc. It works surprisingly well for being the cheapest thing on the car.

Wiring under the left rear seat, showing main cutoff, relays, fuses, alarm buzzers, and the PWM solid state relay (Hella) for the fuel pump is bolted near the fuses. The blobs with heatshrink around them are thermocouple controllers. Those little orange things are Wago splices, they're awesome. The db37 breakouts are from Winford.

Fuel pump and filters under the gas tank. The fuel goes around the front of the beam and through hard lines in the tunnel.

Anyway, it goes pretty well, happy to answer questions about it.

[Busstom]

Excellent! So you went full sequential. Did you build your own main board too?

Very curious about your IAC...is it plumbed to the base of the throttle bodies? Or...? Please explain the operation of it.

I'm sitting on an MS2 wasted spark setup, and debating whether to put it on my '75 Bus or the '64 Bus (I have CB manifolds to go either way).

[joel.truher]

Yeah, I started with MS2 and the 3.0 board, so i spent quite a while hunched over a soldering iron one january years ago when the kids were much smaller than they are now. Now I have the ms3/ms3x setup, still with the same main board though.

The Jenvey TBs have little air ports that work as manually adjustable needles, or they can be converted into 1/4 barb IAC ports. I made a little manifold to make all the hoses the same length, but you can't see it in the pic, it's hiding behind the shroud. The IAC itself is the kit that diyautotune makes, which works with the GM/jeep stepper thing. I didn't think I'd like the stepper valve but it works great.

There's actually a second identical setup, but with smaller hoses, for MAP, using really tiny hose barbs threaded into the manifolds. I think you could do the same thing with 1/4 IAC ports if you put the ports near the upper flange, where the casting is plenty thick.

Having struggled a bit with transient throttle response, I think I've concluded that the CB manifolds are set up for a lot of wall wetting, so I'm not sure a sequential setup makes much difference. Batch/wasted, like d-jet, would probably work just as well.

[ps2375]

Depending upon dia of throttles and cam, there might not be much of a MAP signal to work with for S/D tuning. You may need to go Alpha-N with a TPS to tune it. I hope the S/D works for you.

[joel.truher]

You're right about that, MAP isn't very useful except when the throttles are almost closed. There's a TPS hiding in the back on the left, and I run the ITB mode, which seems to work fine.

The main tuning issues I'm having are transient response (a blip is always lean then rich), and a tendency to get richer as the engine becomes fully heat soaked, e.g. idling for a long time. I think that might be due to MAT reading lower than actual, since it's just near the intake rather than being in the manifold itself. There's a correction for that, but fiddling with it gave really high MAT numbers, so I stopped. Maybe I'll get back to it.

[andy198712]

Any details on your Pi? Which code you use and what’s the screen?
_________________

[buguy]

Very nice! I almost used the Wago splices in my build.

[raygreenwood]

[joel.truher]

The Pi screen is just the 7 inch one the Pi people make:

https://www.raspberrypi.org/products/raspberry-pi-touch-display/

It has VESA mount holes on the back, and there's a Ram mount that fits it. It's just the right size to fit between the glove box and the steering wheel.

It's running Raspbian and Tuner Studio using a USB cable to the Megasquirt. I've made the dashboard more complicated over time, so I can see things like IAC position, or closed loop AFR correction, etc. One surprise is how low the oil pressure gets, it's like 7 psi when fully hot.

I thought the touch screen would be useful but it hasn't turned out to be, I have a keyboard and mouse hooked up to it. Note some keyboards will melt in a hot car.

The power supply is just a USB charger in the cigarette lighter, kinda surprised it works but it does.

[theDrew]

nice!

might look into the ITB calculation, it blends MAP with Alpha-N, worked nice for me when I had my NA setup. Read over the manual a few times on it and it will become clear how it works and recommended setup for it.

i used to use the same IAC setup, and eventually ditched it because it was just a source of vacuum leaks and didn't have much authority to be useful.
_________________
Turbo 2276 MS3X build http://www.thesamba.com/vw/forum/viewtopic.php?t=673125
1985 Vanagon Campmobile w/ 2005 EJ25

[TinCanFab]

My ITB setup works better on regular MAP settings. How is your vacuum hooked up? I have a hose from each runner going into a log behind the shroud on my firewall. Then, the log connects to a GM external MAP (Microsquirt) with a restriction fitting in that hose. The MAP signal I get is smooth and I basically tricked the computer to think the engine has one intake manifold.

My "restriction" is a broken 55 Weber IDF idle jet
_________________
Check out my truck brought back from the dead... http://www.thesamba.com/vw/forum/viewtopic.php?t=420762&highlight=sprayed+blood

They're never really ever finished 58 rag build...
http://www.thesamba.com/vw/forum/viewtopic.php?t=658092

[joel.truher]

that looks nice. i have a hose from each port leading to a little 6-way manifold that goes to the onboard map sensor on the 3.0 board (the remaining tube goes to the fuel regulator). the difference is that yours has a lot of volume to smooth things out; mine has essentially zero volume. as i understand it, newer ms code takes the minimum of the signal for each cycle, so physical smoothing is less of an issue than it used to be. also i was concerned with responsiveness: as it is, my log says that map lags tps by about 50ms, which is already a lot (i.e. i think it's one of the reasons for a little one-event misfire blipping the throttle), so more volume would make it slower.

[theDrew]

i just use a MIG welding tip as my map restriction.
_________________
Turbo 2276 MS3X build http://www.thesamba.com/vw/forum/viewtopic.php?t=673125
1985 Vanagon Campmobile w/ 2005 EJ25

[Busstom]

[theDrew]

sorry, it looked like you had an external GM sensor....disregard
_________________
Turbo 2276 MS3X build http://www.thesamba.com/vw/forum/viewtopic.php?t=673125
1985 Vanagon Campmobile w/ 2005 EJ25