Everything about CB Performance Black Box

[theDrew]

forget what I said, its back again. damnit all.

how bad is it on the engine? I'm still trying to use it during all this "testing"
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Turbo 2276 MS3X build http://www.thesamba.com/vw/forum/viewtopic.php?t=673125
1985 Vanagon Campmobile w/ 2005 EJ25

[Fred Winterburn]

[stan_tichomirov]

[Porsche60]

[Porsche60]

I'm sorry to cut in line of the cranking issue but
I should add another Pro of the Black Box (or any programmable ignition with MAP sensor)

I've already mentioned about it in an older post.
This description is based on N/A engines.


The pro

You have two cars, one has SVDA and another has the black box.
If you go higher altitude while timing properly set at sea level,
SVDA's timing would be retarded compared to the black box.
It means less performance and less fuel efficient with SVDA.
The black box advances ideally at any altitude.


Why?

Ignition timing should be advanced or retarded depending on the manifold pressure,
because the manifold pressure is directly related to burning speed of fuel mixture and the chance of knock.

The manifold pressure almost equals to the atmospheric at WOT.
When the atmospheric changes, the manifold pressure also changes.

The WOT manifold pressure at a hill top would be lower than sea level (100 kPa), let's say 90 kPa for example.
So the timing should be advanced a few degrees more than at sea level.


The black box uses MAP (Manifold ABSOLUTE Pressure) sensor
so that can compensate timing ideally, whatever the atmospheric pressure is.


On the other hand, SVDA's vacuum unit can't sense any absolute pressure.
It just compares the manifold pressure to the atmospheric.
And it advances timing if the manifold pressure is lower than the atmospheric.

The vacuum unit won't advance at WOT whatever the manifold pressure is.



Note

In reverse, higher to lower altitude could be a problem for the Black Box as well as SVDAs.

If you live in high altitude and tune your black box only in your town,
you will never see higher MAP than the atmospheric, let's say 90 kPa.
So you may not set the maximum MAP on the timing table up to 100 kPa.

Then, if you go down to the beach, your timing might be too advanced near WOT.

It is important to set timing up to 100 kPa if you go sea level.
Then, virtually you will never need to adjust timing at any altitude.

[GTV]

I gotta say, the CB Black Box really looks like the bees knees. But as long as this kickback issue remains a problem, it will keep me from buying one. I hope CB gets it sorted out.
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EMPI Power Rules!

[Steve Arndt]

Porsche60,

That is all quite true. The issue is if you have a block in your map programmed for extra advance at a lean cruise at zero elevation, when you go up in altitude (down in pressure) you will be operating in this highly advanced portion of the map when under heavier load.

That is where a second map sensor, a barometric sensor, comes in handy. My ECU has two map sensors, one for the engine and one that measure real time barometric pressure. It has supplemental maps that must be programmed to offset both the fuel and ignition timing wrt barometric pressure.

Most bare bones ECUs with a single pressure sensor only measure barometric pressure at key on and it is static until power cycling.

[Porsche60]

BTW, this is my current timing map.

It's not much changed from the map posted in page 3, in high RPM and high MAP area.

Mainly, I changed idle, cranking, low RPM driving, and decel.

I can't improve more from this point without dyno.

[j-dub]

For the sake of discussion here is my latest map, wanted to add more timing in the cruise section.

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1957 Oval rag
"POLICE STATION TOILET STOLEN ... Cops have nothing to go on."

[EVfun]

Has anyone running this without a carb system that doesn't have a choke tried to set the idle timing so it has a minimum advance at around 1000 rpm (at higher vacuum levels seen with the throttle released) and advances as the idle speed declines? Advancing the timing has the habit of increasing the engine rpm. My thought is that by advancing the timing as the idle speed went from 1000 rpm down to 500 rpm it should help keep the engine running after a cold start.
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[Porsche60]

[clonebug]

[FreeBug]

Even on vacuum advance carbs, you will notice when the choke is on, it holds the throttle plate open so as to expose he vacuum port, among other things.

[j-dub]

On my engine i was playing with the idle timing based on RPM. For example my target idle RPM is 850:

750 RPM 15 deg
850 RPM 12 deg
950 RPM 8 deg

You can adjust your numbers accordingly but the idea was when it was cold and idling lower the extra RPM would keep it from idling slow. I was pretty effective, however I abandoned it during starter kickback troubleshooting.
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1957 Oval rag
"POLICE STATION TOILET STOLEN ... Cops have nothing to go on."

[mark tucker]

so... your pulling timing out at low rpm as the rpm increases???Ilike low timing at spinning then add when it fires off& comes up to idle at about 13 degrees idle speed,no kick back smooth idle,but I dont have one of these fancy boxes. not sure I could keep all my hair with all those numbers on that chart.I only have 8 fingers.

[j-dub]

Yep, the idea is completely optional but is fun to set up.

You set your cranking timing to what ever you need, 8 degrees or so. Once it fires off the RPMs increase to the next timing bin. This second bin would add timing to keep the idle speed up when it is cold. The target idle speed would be the third bin and would be whatever you engine likes and the fourth bin bin up would be to control hot idle and would have lower timing, however I have never found it necessary.
As soon as you hit the throttle it would be on the next bin, out of the idle range, so this dip in timing would not be noticed.

Hope that makes sense.
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1957 Oval rag
"POLICE STATION TOILET STOLEN ... Cops have nothing to go on."

[Porsche60]

what number is advanced?

I run 14 degrees idle and it is advanced than stock 7.5.
But it doesn't help cold idle.
My carb is single and fuel evaporation is the problem.


For the Megasquirt, I think it advances timing along with enrichening AFR while cold.
Plus, fuel injections don't have evaporation problems.
It's different story.


Black box has no temp input so you can't change timing depending on temp.
I don't find significant RPM or MAP difference between temps.
If you set idle for cold temp, it's not good after warm up.


The stock carb and distribtor setup has similar idea that works together with choke.
It's done by ported vacuum.

Stock choke opens the throttle plate a little, which increases RPM and enables the ported vacuum.
At this time, vacuum advances timing +10-12 degrees.

Once the engine is warmed up, throttle plate closes and ported vacuum is closed.
Zero vacuum advance and back to 7.5 degrees.

I emulate that, of course with choke system.
Choke is the only temp sensor on my engine.

[Porsche60]

[kikkegek]

I am experiencing some strange stuff I wanna share with you guys.

I have a Autogauge vacuum gauge in my dashboard and it read different values as the BB.

this one:

BB Gauge
-2,2 VAC 0 inch
-12,2 VAC 15 inch
-9 VAC 12 inch
-15 VAC 18 inch
-17 VAC 22 inch

I have asked Mark from CBP about it and the manufacturer of the MAP sensor says that it is wel within the range of accuracy of the 5 BAR MAP sensor.

I was wondering if any of you guys have compared these values?



another thing is I found a bug in the timing table. During WOT runs the timing would jump from the right of the table to the left of the table, causing hesitation during acceleration. this was because the reading would go off the chart and therefor jump to the other side. it is solved by making sure you choose bounderies you will not reach during operation. I found out together with Mark, maybe there is a update by now that fixed it?


my last problem I am having is rough idle and hesitation during take off when the engine is warm. Iĺl start loosing connection to the black box and idle quality will become pretty bad. when I take of the first few feet are rough, then it smoothens out and runs fine....I have absolutely no clue what maybe causing it.

Do you guys have any tips?


What are you guys using for signal input for the Black Box?

[Porsche60]