VW Bus Microsquirt Project

[ger_man]

I'm about to install Microsquirt on my 72 Bus and had a few questions some of you may know the answer to. First, here are the basics:

T4 1800 stock
stock late bay FI plenum
stock TB that has a WOT switch (and no shaft for TPS)
Bosch hi-z 0280150206 injectors
GM 1-bar MAP
LC-2 O2 sensor
Ford PMW IAC
dubshop crank trigger
dubshop IGN-4VW signal level coil pack
dubshop 'coolant' temp sensor
dubshop Mex Pkg IAT
walbro gsl393 fuel pump (and pre/post filters)
bosch 0280160200 fuel reg
CB Perf Tank Tee

1. For this application do you think it is worth trying to rig a way to have TPS? I actually bought a 1990 Escort 1.9L throttle body with the PMW in it and a TPS to try but decided I'd like to try a stock TB if possible first since it would be a much cleaner install.
2. I found an ignition advance table for a T4 in a search but I'm not sure it was right for a bus. It seems to me there are 3 points to incorporate in to the table which are idle advance, WOT advance and cruising 'vacuum' advance around the 3500rpm area and light throttle. If Anyone knows good numbers for a bus for those 3 I'll blend a table to that.
3. Dwell for IGN-4VW?
4. Has anyone mounted an O2 bung in a stock bus muffler or tailpipe? If so where?

[ps2375]

I'll answer what I do know, a TPS is a bonus and not a needed option. It allows a few more features to be used but are not really needed for a nice running motor. You could incorporate the WOT switch as a TPS for Flood clear function and a couple of other features that are based off of a WOT throttle position.

Dwell for that coil(the wasted spark one?) should be the standard numbers in TS. The important setting is the "going High" or "going Low" setting for the trigger to not burn up the coil.

That's all I can help you with.

[ger_man]

Thanks for the info. I'm a newbie on EFI so I'll have to read up more on the flood clearing but I'm glad to know I may be able to use that switch for something.

[ps2375]

It's really hard to flood an efi motor. Only time I've kind a done it is on an initial start on a motor with an unknown tune. Once the tune is set, flooding is very difficult to achieve.

[ger_man]

Another question I thought of is "where do you connect the MAP sensor port?". I was thinking it would be on the vacuum port on the throttle body like where distributor advance would go but by looking at it it appears when closed the port is on the top side of the throttle plate and would be at atmospheric pressure. Since I'm trying to go without TPS it seems like this wouldn't work. Would it be better to get a true plenum vacuum for this?

[ps2375]

Yes, you want manifold vacuum, not ported vacuum. That is very important.

[Clonebug]

I think PileDriver used the stock Type IV TB I'm quite sure and has retrofitted a TPS to it.

[ger_man]

I could probably rig something off the actuation side of the TB for a TPS but the other side is actually sealed, which I like since, I've heard these TBs can be notorious for leaking. This one seems nice and tight and has no scoring on the inside from the plate hitting due to wobbled out arm movement.

[panel]

This might help.....Not sure if he has a build thread but you can look up all his posts if you're interested.

viewtopic.php?f=66&t=147737

viewtopic.php?f=66&t=144658

[ger_man]

Great info in these threads except I wish those ignition advance tables were still there. I've got to get more adept at searching around here as there's good stuff if I can find it. I did take a stab at my own table based off curves I found for a 205ZB which I believe is for a bus. Does it seem right that vacuum advance is pretty much all in at 70kPA as that is about what i calculated? If I can figure out how to post a picture of my table I'll do it. Do I have to upload the picture first and then link to it?

[ger_man]

For others who may run into this I realized that the VW wasted spark coil pack uses LS1 style connectors. I had been trying to figure out for a couple of days with no success. Then I thought of my son's LS1 conversion project going on so I pulled one of the wires to see what it had and voila it snapped right in the VW coil pack. I ordered MSD 3304 spark plug wire boots and terminals to use.