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S2 931 EFI Conversion DIY
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924RACR  



Joined: 29 Jul 2001
Posts: 8357
Location: Royal Oak, MI, USA

PostPosted: Fri Jul 03, 2020 10:08 pm    Post subject: Reply with quote

Fasteddie313 wrote:

Turned EGO control off to tune.. Turned the step size way down and the % cor way down when I turned it back on..
It's good


Just realized I need more details on this, I think... what did you end up with for settings when complete?

Turning mine off now, didn't realize it'd be in there screwing with things while trying to tune... thanks for mentioning it...
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2104
Location: MI

PostPosted: Sat Jul 04, 2020 4:45 am    Post subject: Reply with quote

924RACR wrote:
Fasteddie313 wrote:

Turned EGO control off to tune.. Turned the step size way down and the % cor way down when I turned it back on..
It's good


Just realized I need more details on this, I think... what did you end up with for settings when complete?

Turning mine off now, didn't realize it'd be in there screwing with things while trying to tune... thanks for mentioning it...


I don't have autotune.. I do it all manually so I don't have any experience with what that does really..
I have used the VE analize in megalogviewer a lot and it gets it close, but sometimes throws some things off when it picks up throttle stabs/drops or other unique things..



That is what I'm running for EGO right now and seems to work good but I don't really know what I'm doing so its whatever..


At cruising speeds/loads I don't get any misfires between like 10.0 and 16.5 AFR.. It'll eat about anything in that range and feel like it runs fine..
It was cruising a bit lean bouncing into the high 16s and I could feel it miss a little when it did that, but I've got my cruise back to about 15 now I think..

Took a bit of a trip to go get Ford parts first thing yesterday and it wanted to bounce into the 16s while cruising and that was a bit scary, so I did an on/off throttle thing there and back so it wouldn't sit too lean..

What do you figure the chances of engine damage would be from cruising super lean? Think it could burn anything like pistons/valves or is that only going to happen at higher loads?
Cause it'll cruise like a boss at 16.0 if it's safe, bet it'd get amazing gas mileage like that, lol.. But I don't want to burn anything up..

The last time I was tuning it was like 40F outside, and now it's like 85F, so maybe that's what made me a little lean in cruise from then till now..
Might be an adjustment needed to MAT compensation.. Not sure..

When I step on it it goes rock steady into the 12s at stock boost so I'm pretty happy with that, and down into the 11s for higher than stock boost.. Aiming for like 13.5 @ 100kpa..
Works..

Cruise the AFR is less steady for some reason.. It'll bounce around about .5-.7 AFR cruising..
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2104
Location: MI

PostPosted: Sun Jul 05, 2020 1:16 am    Post subject: Reply with quote

924RACR wrote:
I noticed I was going FULL lean (22.4 on the gauge/out of range) on higher RPM coastdown.


I cheated and just use full fuel cut on overrun to solve most of the coastdown tuning..



Might up the KPA threshold to like 33-35 though so it works a little more in like 5th gear cruising..
The higher it is the more it works, but the more it is noticeable between on/off throttle..

Really depends on engine temp too.. I don't get as much vacuum until it's fully warmed up.. So it doesn't work as well while it's still cold.. I notice..

My TPS doesn't always return to 0% but always under 1% so I consider anything under 1% basically a closed throttle..


I don't have a decel valve or idle valve or anything like that.. Just a ball valve where the idle valve thing used to be that I use to set my idle, because my new VW TB doesn't have an idle adjustment on it..
Gotta hold a touch of throttle on really cold starts for a few seconds to keep the RPMs up, but it works plenty well enough for me.. Well enough to make me not want to mess with an electronic idle valve, and I can save those available outputs for something more fun than idle control..
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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Sun Jul 05, 2020 9:54 pm    Post subject: Reply with quote

Cool, thanks for sharing that.

Yeah, I'm sure the AAV isn't needed now, but I don't mind the idea of driving my car until the snow flies, so starts in 40-deg weather would be nice... so I'll keep that plumbed in.

Though I will have to re-route a bunch of those things - probably going to end up sketching it all out before I make the tubes, just to figure out the most efficient way to do it.

Hope to have more parts starting to arrive again today, get those main tubes finished off and get back to running soon...
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924RACR  



Joined: 29 Jul 2001
Posts: 8357
Location: Royal Oak, MI, USA

PostPosted: Sat Jul 11, 2020 4:41 am    Post subject: Reply with quote

Got it all plumbed in. Whew. Well, actually, still have to mount and plumb the MBC, but that can wait until I get it decently running with stock boost. Still have the crazy lean situations on coast-down, along with odd irregularities when boosting.

Some misfiring, some more just an issue of the AFR bouncing all over the place, not sure why - PW seems smooth, but RPMs on a steady WOT pull to 4000 rpm seem to get pretty jagged. Not clear at this point if this is a symptom or cause; get some minor jiggling of timing, but less than a degree. The RPM sawtooth trace is mirrored in the VE, again not sure cause vs. effect.

Gonna keep hammering away at it...
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Sun Jul 12, 2020 3:16 am    Post subject: Reply with quote

How does your RPM look on your logs?

Maybe your sensor isn't close enough to the teeth?
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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Mon Jul 13, 2020 5:32 am    Post subject: Reply with quote

RPM is smooth except when it isn't.

Sensor air gap is about 0.8mm, should be very happy at that. Unless it's wiggling around. Probably should recheck it, could even move it closer I suppose. Did reinforce the bracket with triangulation, so hopefully it isn't changing/moving around.

Would there be a way to take a tooth/trigger log while running into the problem? I thought that was just a while-cranking thing...

Things are improving with a heap more advance. Still working it. That seems to be one of the biggest single things, I think, to improve it; above 20 degrees it starts to get good, trying not to overshoot and hurt things.

The overrun fuel cutoff was a big improvement, very very happy with the results on that.
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Mon Jul 13, 2020 5:56 am    Post subject: Reply with quote

924RACR wrote:

Would there be a way to take a tooth/trigger log while running into the problem? I thought that was just a while-cranking thing...


IDK.. Try it..

Since you have a 36/1 wheel (or whatever it is), it might be a common question with the MS community..
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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Sun Jul 19, 2020 10:50 pm    Post subject: Reply with quote

Re-checked my sensor gap, it's still a solid 0.7mm. Haven't tried a log, but did run on the highway the other day, it's not half-bad.

I think my misfire is a cyl#3 issue, not electronic. It recurred the other day, with a good plug I'd previously swapped in. I removed the plug (after switching plug wires around to ensure they weren't the source of the issue) and cleaned/heated it with a propane torch, then reinstalled hot.

Fired right up (well, it always does, these days!!) and the cylinder was happy.

I had a bad rebuild with problems properly seating the rings; I suspect that #3 is still somewhat fouled rings. Needs a lot of Italian tune-up time to clear, seems like. Having an engine that runs properly all the time thanks to the MS seems to help a lot - the old CIS was IMO a major contributor to the fouling of the rings.

Still lots more to finalize and tidy up on the install, but I'd say it's about at the point where I'd be game to start dailying it, or will be soon.

But I read up some more, and I think I'm going to migrate to the VW 032 905 106F ignition unit. This will replace coil, distributor, and igniter, while reusing my stock spark plug wires, and is able to be plugged directly into the MS. It's also only $50 on FCP Euro for a new Bosch unit! While reusing the stock coil and distributor are the easiest, cheapest way to get up and running on our cars, for sure, this should end up being more reliable.

Got a few races coming up in the next month I need to focus on, then I'll work on getting that swapped in...
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Fasteddie313  



Joined: 29 Sep 2013
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Location: MI

PostPosted: Mon Jul 20, 2020 4:13 am    Post subject: Reply with quote

924RACR wrote:

But I read up some more, and I think I'm going to migrate to the VW 032 905 106F ignition unit. This will replace coil, distributor, and igniter, while reusing my stock spark plug wires, and is able to be plugged directly into the MS. It's also only $50 on FCP Euro for a new Bosch unit! While reusing the stock coil and distributor are the easiest, cheapest way to get up and running on our cars, for sure, this should end up being more reliable.


Still need a trigger wheel with that I imagine?

I will do ignition eventually..
Either I will figure out how to control an ignition box off the MS without adding a trigger wheel, or if I have to add a trigger wheel I'll probably just fire 4 LS coils directly off the MS..

I hate to remove the originality of the distributor and coil, but LS coils having built in igniters and all, seem the easiest/best to me..

I think I have my boost and fuel down pretty good now, but I bet their is a bunch of power left to be had in ignition timing over the extremely conservative S1 timing I'm still running..


This is what I get for plotting the original 931 S1 ignition timing...


This is what the 931 S1 should do with the boost retard can vac line removed..


Which is pretty close to what raceboy recommends/tunes to (on boost).. But still not quite as aggressive as his..



So I think sometimes about trying to run without the boost retard on my original ignition and see what happens..
But you know.. Could be dangerous..
Might now though that I am pretty confident in my fuel AFR reliability..

But, other than more power, I really want ignition control just so I can set up anti-lag, just because it would be loud and cool, not that it would actually be useful, unless I about double my rear tires..

On another note my car has turned into a GAS HOG!!
It's kinda ridiculous actually.. I'm filling it up like every other 2 or 3 days and it's getting expensive..

I have turned it down to like 16-17 psi running in the low 11s, because it's just about as fast as 20 in the mid/high 10s, which is probably just burning more fuel for no reason..

Feels like it runs the best on boost at about 12.0, but not sure how dangerous that is, so I don't..
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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Mon Jul 20, 2020 8:17 am    Post subject: Reply with quote

Yeah, my timing map is a lot closer to raceboy's - will have to shoot it over. Though I top out IIRC at 38 degrees to be safe.

Yeah, I needed a trigger wheel anyway because S2, so this coil setup would make sense to me for cost-effectiveness...

Interesting points you make about 16-17 vs. 20psi. Maybe it needs more discrete data to really hone in the tune precisely enough to benefit from any more boost... time for that knock sensor etc...
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2104
Location: MI

PostPosted: Mon Jul 20, 2020 11:39 am    Post subject: Reply with quote

924RACR wrote:
time for that knock sensor etc...


Time for another thousand or 2 bucks right?
Knock, EGT, backpressure, pre-ic MAT, oil press/temp, EBC, coils, trigger wheel, trans, wheels/tires, etc..
Ok maybe more..

I think it's the turbo reaching its limits.. Doesn't even hold flat boost that high..
Could have to do with the 4.10 housing and that one intake restriction I have yet to remedy in the original lower charge tube..
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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Mon Jul 20, 2020 9:39 pm    Post subject: Reply with quote

LOL yeah... well, at least 16-17psi can't be all that boring, eh?
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Vaughan Scott
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'82 931 Plat. Silver
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Fasteddie313  



Joined: 29 Sep 2013
Posts: 2104
Location: MI

PostPosted: Tue Jul 21, 2020 2:48 am    Post subject: Reply with quote

924RACR wrote:
LOL yeah... well, at least 16-17psi can't be all that boring, eh?


Nay...
It's respectably quick and real healthy feeling around there..
Enough passing power to drive at my preferred cruising speed mostly unimpeded..
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924RACR  



Joined: 29 Jul 2001
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Location: Royal Oak, MI, USA

PostPosted: Mon Jul 27, 2020 9:51 pm    Post subject: Going for ignition upgrade Reply with quote

Well, it was nice to prove out that the stock ignition could be re-used, but I've had enough of somewhat cobbled-together old parts, and I'm going to take the next step and upgrade the coil side.

Will be ditching the stock coil, igniter, and distributor and replacing with the VW part 032 905 106B

This is a direct-fire coil pack, about $50 from ECS right now, and will power directly from the MS. I'll use the distributor replacement mount for the EDIS coil. This also has the advantage that it's not only cheap and easy to install, it also even uses the same plug wire connector as the stock wires, no need to replace those (have the nice Kingsborn wires).

Connector is 1J0 973 724 and that seems to be available cheap on Amazon with a pigtail...
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'82 931 Plat. Silver
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