Vanagon SVDA Distributor Timing

[luftvagon]

I'm sharing my current "base" vanagon svda-like ignition. It follows the vacuum advance, and mechanical advance of SVDA distributor.

ignitionTbl1_2015-10-11_20.57.29.msqpart.gz

It could use a bit of advance @ 985 RPM from 30 kPA to 65 kPA, but other than that, its very close to stock.

[westypoo]

this is awesome. very helpful to others getting a start.

[Piledriver]

IIRC the factory SVDAs and DVDAs had far more vac advance, sooner.
The WBX has radically different Heron combustion chambers, 1mm deck/plenty of squish from the factory, and needs less timing.

Which model//chart is yours based on?

The easiest way to cook your heads is retarded timing at idle like the factory used.
They did it to get it to temp quicker for emissions reasons, with no way to turn it off.
You can duplicate that process, but much better by using the "cold timing" feature, as well as pull timing at higher CHT.
If you have a wild cam you will probably want to ADD a lot of timing cold.

Don't be misled by the names, cold timing and WUE can be setup to work over the entire extended temp range, and do not turn "off".

Try 12-15 BTDC as a starting place, and use idle timing, idle timing stabilization (or whatever its called) and idle VE if on MS3.
Keep idle off the main map, keep that optimized for driving.

IIRC the only MS version that requires the idle area setup in the main tables is MS1.

[luftvagon]

Pile, I have since made a few adjustments since:



I don't use "cold advance" as it is another variable to fiddle with during cold starts. My current cold starts are close to factory perfect. Hell, they are better than I could get them with L-Jet.
This is a good compromise for a daily driver I think.

[aircooledtechguy]

I'm not an MS expert like some on here, but I do have several years of refining my own cars with Mario on speed-dial.

To me, that curve looks like a "009" with added advance for cruising; very linear curve. You will be giving up a lot of acceleration, throttle response & HP from idle all the way through 3k depending on the cam you are running. A vacuum advance dizzy will pull 8-12+ degrees typically right off idle as you stab the gas in the low rpm/mid load area to allow you to power up to speed. I don't see that. I see "009 style linear advance as the rpm increases. This is precisely why the "009" has that famous dead-spot in acceleration.

Obviously you do not have the dead-spot, but you are leaving acceleration, throttle response & power on the table with this curve.

The way I have mine tuned is I first get the response off idle tuned. I watch the flying dot as I stab at the gas off idle and while driving. I add timing little by little and look for the response to increase. The motor will feel less "lazy" as you get it right. Then I find the rpm/kpa areas that I cruise in (IE - 2200-4000rpms in the 60-80kpa ranges typically with a mild cam). The kpa range really depends on the cam you have. Then I try and optimize the advance in this range. As you add advance, you can generally pull out fuel and your mileage goes up. I use my CHT and AFR as a guide in this tuning. Then once that is nice and my mileage is better and it's smooth, I blend this into the rest.

Every motor is different. That's why dizzy's suck.

[Piledriver]

I agree, that's still hyper conservative and likely retarded enough from ideal to drive the EGT and CHT up.
The top line should be ~all in by 2600 or so, with maybe 3 more degrees gradual increase to redline.
"vacuum advance" should be more of step function, and be ~45-ish BTDC at 65 KPA and 3200 RPM.
Over 50 even 60 BTDC won't hurt anything at 40 KPA, things burn reeeaaalll slow in that range if at all.

WOT is very seldom 100 KPA unless you live on the beach.
30 KPA isn't typically a useful row: Its the ~equivalent of WOT at 30,000 feet.
Fuel cut should be on far before then or you are just blowing fuel out the tailpipe.

Add an 83 or 95KPA line or something where you need higher resolution for max map enrichment or a lean/rich transition.
You should do the same for RPM bins for the same reason.
(both timing and AFR target tables, lean or rich of stoich require more timing, lean moreso)
Use the bins for areas where the tables need them, nonlinear transition areas, the firmwares interpolation will generate a smooth transition on linear areas even over a huge range.

Also use load/time enrichment if your ECU/firmware has it.
Use idle timing and idle VE as well.
The main map is for drivability, not idle.
Use the idle control features for idle. This is not an MS1.
It helps me to use the programmed idle timing and VE vs the PID triggered as you can avoid the PID delay.

"Cold advance" as mentioned does not have to be advance, it can be used as retard to greatly speed initial warm up.

I have found (very contrary to conventional aircooled wisdom) a few degrees too much timing (at 85-90 KPA and below) is far better efficiency and lower CHT/EGT wise than a few degrees too retarded, and knock isn't even a concern below ~85 KPA unless your heads are way too hot already or you have borked heads with hot spots in the chamber or exposed plug threads...
That won't cause knock anyway, that will cause preignition which is ~infinitely worse.

[luftvagon]

All good and valid points. I'm just sharing a "base" map for people just getting into tuning to get their van moving. I cant use idle control because I don't have a TPS. It's required.

[Piledriver]

Do you have the idle switch setup?
That can become a "TPS" for idle logic purposes while still a switch via a pair of resistors, or drive an actual TPS.
I almost tried the switch setup myself when my original tps flaked out a few years ago.

[luftvagon]

On (Federal) A/C Vanagon they had (WOT) enrichment switch, but no idle switch.

[Piledriver]

Oh well, at least you have the output half shaft and a place to put the TPS, so you're 90% there.

[luftvagon]

Oh well, at least you have the output half shaft and a place to put the TPS, so you're 90% there.

Yes, but it's on the wrong end I tried to experiment with attaching a sensor, but there was just no way to magically attach it to the throttle body, without modifying the tb. Old pic during mock-up:
http://i.imgur.com/wOwtk.jpg
I've been looking for spring pull type TPS, but they are not very accurate, and may be inconsistent. Eventually, it may be worth getting all new plumbing. Everything works ok now, so no rush.

[Piledriver]

The TB is not really hard to modify for a TPS.

If you don't have the output shaft, you can make up a coupler from 1/4" or 6mm rod, by cutting a slot in the throttle shaft, matching tab on the adapter with the required flat and cut to required length...and make sure you bolt the TPS on center. I run a 2008+ GSXR TPS on my Ljet TB that way for the last 80K miles.

A later TPS with the switch setup or a Djet TPS already have the shaft and mounts.
A 50mm TPS off a WBX will also bolt on...

[Mogotraining]

Can anyone point me to a guide for megasquirting my 1981 Vanagon? It’s engine is rebuilt fresh.

[panel]

Can anyone point me to a guide for megasquirting my 1981 Vanagon? It’s engine is rebuilt fresh.

PM luftvagon

[V8Nate]

Great info!