Microsquirt my 1776 Bus

[blue72beetle]

Finally finally finally making the move to megaquirt for my 1971 Bus. I bought a 1776 longblock with an engle 100 cam earlier this year, I put a 205Q distributor and correct 34p3 carb on it, with bigger jets for the bigger engine. I got it running, but I still want to go to fuel injection for all the usual reasons.

After lots of research I already ordered a Microsquirt, and LM2 wideband w/ gauge from DIYautotune.
I already have a complete mexican EFI setup. I also have a sweet Vintage Speed muffler, but it arrived without an O2 port. I thought they all had that. So I'll have to find someone that can weld stainless for the O2 bung.
I plan on going with the following,

Trigger wheel and pulley setup from Mario
IAT, CLT, and MAP sensor for mexican manifold from Mario
IGN-4 from Mario
Walbro fuel pump from Mario
FPR from Mario

I've been doing a ton of reading of the MSextra manuals, website, youtube videos, etc. I do have a few questions I haven't been able to find the answer to.
Mario sells a T-fitting so you don't have to run a return line into your tank. Does this work well in practice? I know with the stock mexican fuel pump, the return is run to the fuel pump, not the tank as well. But from what I read, the stock fuel pump pretty much maxes out at around 45 psi, so I probably don't want to use that, right?

Are the stock mexican fuel injectors low or high impedance? If those won't work well for my 1776 I plan on buying a set from Mario, he has the following:
(4) 19# upto 100 crank HP (Stock)
(4) 24# upto 150 crank HP
(4) 32# upto 200 crank HP
(4) 44# upto 300 crank HP
His 19# are out of stock (or unavailable) so would the 24# be too much for a 1776?

The stock mexican idle valve is a VDO, but it looks just like the 2-wire Bosch. Do you think it will work just the same with PWM control?



Thanks for any help and advice

[Schweg]

I have the tank T running to a walbro external pump and it works fine. No issues that I’ve seen.

You won’t notice any issues between the smaller and larger injectors that your looking at. I have 44# injectors on a 1600 and it’s perfectly fine.

Your setup sounds like it’ll make for a good runner.

[whaczup]

Would love an update on your progress.

[blue72beetle]

I just got my last order from Mario the other day, so I now have all the parts I need. Except for misc stuff like fuel hose and clamps.

I found a local welding shop to weld an O2 bung on my stainless muffler, so that's good to go.

It's getting cold here in northern Indiana so I'm less motivated to go out in the cold garage and work on the bus. But next I need to pull the engine and drain the fuel tank. I suppose I can clean up the mexican manifold parts in the mean time.

Just thinking through things I might have to modify.... I want to use the original oil bath air cleaner, but I realize it doesn't have a port to supply the idle valve with filtered air. So I'll have to figure out something there...

[Chip Birks]

I am preparing to do a very similar conversion to my 65 bus. I just picked up a complete 2004 Mexican 1600, along with all of the fuel system and electronics (previous owner was converting to electric).
I had hoped to use the stock ECU, but I've decided to go the microsquirt route instead. Bought it for a different mexican setup I had for the bus. But couldn't refuse this complete engine when it popped up locally.

I look forward to watching your conversion!

[blue72beetle]

I knew this was gonna be a long process, but I'm hoping to have this running this summer.

I realized I needed a port on the Mexi manifold for the brake booster hose. Dug around in my junk drawer and found a tube the right size. Drilled and tapped the manifold and it fits great. Even cut it so it's flush on the inside. I'll slap some JB weld on the threads after I clean the manifold.

Also installed the temp sensor. Mario's sensor is made to bolt on the tin screw, but I didn't want it to sit on top, and putting it under the tin would make the tin fit wrong. so I drilled a small hole through a fin and bolted it right on the fin. I had originally drilled the hole in the tin thinking that the sensor was the size of the original mexican sensor, but Mario's is much smaller. It worked out though, as the plug fits right through the hole.

[blue72beetle]

I discovered today that the EV1 injectors are taller than the mexican injectors and the fuel rail bolt hole doesn't line up anymore. Maybe I'll try to modify the mexi fuel rail bolt hole down a little.

[blue72beetle]

Almost exactly one year after my bus last ran with a carb, my Microsquirt 1776 project started for the first time today. Now comes the 'fun' part... tuning....

[blue72beetle]

After another year I've got my bus running 'decently' and put a couple hundred miles on it. The idle is pretty high, 1200-1300 rpm. I investigated, used test mode, and discovered the vdo idle valve isn't moving at all. So it was just sitting partially open the whole time. Figuring that the vdo valve may be different from a Bosch (they look the same), I ordered a new Bosch valve from Mario. Waiting on it to come in the mail.

If that doesn't work, I'm tempted to forget the pwm idle and hook up a simple on/off high idle valve, and adjust idle using the butterfly. I'm assuming I'll have to re-tune the whole fuel map if I do this?

[Big Ratfink]

Aside from the high idle, what did you think of it?

How did the tuning process go for you?

[blue72beetle]

The Bosch valve I ordered worked. I got the idle mostly working as much as I could using Warmup/Idle, then turned on Closed Loop Idle and it's pretty decent. Sometimes it's a little high, sometimes it settles down to a nice 1000 rpm idle. Not bad for not being a tuner.
I'd say overall it's 95% of the way there. The frustrating thing is I don't know any Megasquirt tuners around here that are familiar with ACVWs. And Mario never responded to my many pleas for remote tuning.

HOWEVER.....
I'm currently saving my pennies and shopping for a Subaru. Not because of Megasquirt (well maybe a little), but just because of the aircooled VW engine in general. Slow, crap chinesium parts, tired of all the fiddling. If this wasn't a bus, then yes, Megasquirted Air Cooled all the way. But being a bus, I'm just going to do Subaru and be done with it. So I'll probably put the whole MS engine up for sale this spring/summer.

[woodsbuggy1]

Hope you decide to keep your bus aircooled, a turbo or larger motor would fix your power issues. Where in Indiana are you? I am about 30 minutes south of Ft Wayne. Good Luck and let me know if I can be of any assistance.
Kenric