AFR tuning

[Jeff NJ]

So I finally purchased the full version of ScanXL pro, which syncs up with my PLX sensor and ran some logs tonight.

Below is a screen shot of a 2nd, then 3rd gear pull.
Red is boost, topping out at about 14.5
Blue is vacuum, since the boost range capture option starts at zero, so I setup boost and vacuum to be opposite but equal scales, so that the boost/line simply appears to be one line that turns red on boost and blue on vacuum.
Green is AFR, and the values for AFR are on the right side. The yellow dashes are tied to the AFR, so each line is one point of AFR.

As you can see, as I get into boost, the AFR drops, and then as I hit full boost, it continues to vary.

My concern is that the AFR does not get low enough quickly enough. I'm thinking below 12 once over .5 bar is where I want to be??

Also, it seems that AFR starts dropping right as I go on boost, so I am not sure where the boost solenoid from Leask actually is kicking in, if at all. I have a 4600 rpm pill in there right now trying to delay it, but I just don't see that happening on the graph.

The gray vertical line near the center is the point where it hits full boost in 3rd gear, and per the numbers on the left, I am at about 12 AFR at that point, and if you look just left of the line, there is a little hop up, then back to trending down. I did not let off WOT for the entire 3rd gear pull.

Any thoughts from the experts on this data? Anything I should be concerned about, or anything anyone see where I'm leaving power on the table or just wasting fuel?

[smurfbus]

I think that's as good as it can be. you don't mention how high you run but if thats your normal WOT run it looks good. Most of CIS people get much leaner when rpms rise.

[Jeff NJ]

Thanks for your thoughts!

I ran it close to 6k rpm in 3rd gear on that pull, so I wouldn't go much further typically.

Any reason why the AFR is so bouncy while on WOT throttle? I thought it would be more smooth.

[smurfbus]

With CIS those small bumps are always there depending how accurate the WB logs. Some use smoothing so the bumps dont show up but your AFR is still well withing safe margins so I would not worry about those dips and bumps.

I have some issues now with my boost/fueling and yesterday it went over 14afr at 1.5bar boost and the engine took it like a champ. J&S possibly lowered timing and no pinking or detonation was heard. I need to check my wg line carefully today.

[Jeff NJ]

I had issues getting consistent max boost with my TiAl. I couldn't get the right springs in it to get 1.0 bar every time. I installed a MBC from GrimmSpeed and as you can see by the graph, it is very consistent now.

Any insight on the early onset of the AFR's dropping, despite the Leask boost enrichment solenoid set to delay boost enrichment until 4600 rpm? Does the graph look like it would without it?
Anyone have any ideas how to test it?

[Rich76_911s]

Originally Posted by Jeff NJ

I had issues getting consistent max boost with my TiAl. I couldn't get the right springs in it to get 1.0 bar every time. I installed a MBC from GrimmSpeed and as you can see by the graph, it is very consistent now.

Any insight on the early onset of the AFR's dropping, despite the Leask boost enrichment solenoid set to delay boost enrichment until 4600 rpm? Does the graph look like it would without it?
Anyone have any ideas how to test it?

When Brian sent you the enrichments solenoid there were some testing instructions. I have them and can dig them up for you tomorrow. I'd say that it has to be working though, because if it wasn't working it's standard state is closed and you'd get no boost enrichment if it didn't work. At least that is how I understood its function.

[Jeff NJ]

Originally Posted by Rich76_911s

When Brian sent you the enrichments solenoid there were some testing instructions. I have them and can dig them up for you tomorrow. I'd say that it has to be working though, because if it wasn't working it's standard state is closed and you'd get no boost enrichment if it didn't work. At least that is how I understood its function.

Hmmm. Well it turned out my WUR enrichment system wasn't working anyway, so I wonder if I have just adjusted the wur boost enrichment so that it is as if the solenoid wasn't there at all. I did have to lean out the enrichment a good bit.
I have fixed the WUR, but I am not sure the solenoid is working.
Ill look for my instructions and if I cant find them, I will let you know and would really appreciate if you send them to me if you can find them.

thanks Rich!

[Rich76_911s]

Jeff if you don't find it I'm sure I can. I'll scan a copy and email it to you. Glad to help out.

I had never heard of the scanxl program. Looks pretty awesome. Is there any way to get tach info in the graph as well?

[Jeff NJ]

Originally Posted by Rich76_911s

Jeff if you don't find it I'm sure I can. I'll scan a copy and email it to you. Glad to help out.

I had never heard of the scanxl program. Looks pretty awesome. Is there any way to get tach info in the graph as well?

I found my solenoid valve instructions and will test it out tomorrow, but appreciate the offer to send it to me!

The PLX has a usb cable that plugs right into my Surface tablet and that is what captures the data, so I would need to somehow capture rpm with the PLX, which I don't see how. Without an ODBII port, I don't think I can capture rpm. I have tried. I actually opened a ticket with PLX devices tonight asking them how.

What do you use for an AFR gauge? Maybe a different system captures RPM natively?

It was a pain in the ass to setup, but once I figured it out, it works well.

If you or anyone else buys ScanXL, I would be happy to send over the config files so that you don't have to spend a couple hours figuring it out and setting it up like I did.

[smurfbus]

I have Innovate LM-2 dual wb and it has IIRC 5 different Voltage inputs and I use one lead from my rpm wire to log RPM and one other for boost.

[s5uewf]

I don't think an AFR of 12.2 or 12.3 is bad. I think in the 11's is a bit rich. There are threads in this forum that cover AFR's in a lot of detail. I think you are OK. Of course, it depends upon what your timing is, as well.

[Jeff NJ]

Originally Posted by s5uewf

I don't think an AFR of 12.2 or 12.3 is bad. I think in the 11's is a bit rich. There are threads in this forum that cover AFR's in a lot of detail. I think you are OK. Of course, it depends upon what your timing is, as well.

Timing is stock specs. Can't remember it off the top of my head, but I have checked it recently.
So if you look at my graph, on full boost (1.0 bar), AFR starts at about 12, goes down to high 10s and then slowly climbs back up to right about 12 when I let off the gas. This was a 3rd gear pull and I never let off WOT. How would I adjust to keep it from going too rich right off the bat, and then leaning out as the rpms climb? Is that even possible with CIS? I assume the enrichment solenoid is there to reduce the early richness - I will be checking that functionality tonight. Maybe I'll change the pill to a higher rpm assuming it is working, but I don't know if I can tweak anything to keep the AFR's more consistent across the RPM range on full boost.

[smurfbus]

CIS is like that. If you want adjustability you need frankencis or aic-1 or similar gadget to control the fueling.