Can you help me with these AFR Graphs

wcc · 03:24 PM

I finally got my LM-1 hooked up to the laptop. I usually had someone read it for me as I did a lot of runs over the summer. Well the last time I thought I'd record some sessions and see how the software works. I'm quite surprised at the actual graph. I mean it is all over the place with the engine getting very rich. The car runs great and doesn't make any funny noises etc.

I have GHL headers, K-27, .8spring, zork, with a B&B intercooler.

Here are the graphs:
Session 1:

Session 2:

Session 3:

Help me understand this data. Should I lean it up some, leave it alone? Why are the graphs so jagged?

Thanks in advance!

jbrinkley · 10-13-2008, 04:16 PM

expand the timeline and smooth it just a little.
you don't say what gear(s) you did this?
try to pick a section of the timeline with one gear, like fourth. And post a pic of that.
Get a pick up clamp to log rpm (cheap) and no more difficult to do.
It's kinda hard to look at that the way it is.
if you want to email me the file I can play with it and post it.
is from 19 sec to 28 sec fourth gear?

jerrybrinkley at hotmail

jt1 · 10-13-2008, 05:01 PM

You can smooth the curve by going to Channels/smooth channel/LM1_O2, then using the slider to smooth the graph, about halfway is normally pretty good.

It's hard to tell from just a A/F graph, but that looks pretty lean. You really need to log rpm also, then the shifts are apparent and you can tell where the AFR's are in the rpm range.

John

wcc · 10-14-2008, 01:06 PM

I just ordered the clamp and connector, but they won't be here for a few days. In the meantime here are the smoothed out graphs. This recorded data was from about a month ago so I can't really say when a shift happened. Maybe it good enough to do some tweaking? If not, I'll wait till the clamp gets here and take new fresh data with RPM info.

jbrinkley - I emailed you the file as well...

Session 1:

Session 2:

Session 3:

jbrinkley · 10-14-2008, 02:17 PM

hard to really tell without rpm and or boost on there.
Looking at it I think you can only assume/hope that the low numbers were on boost and the higher instances were off boost/part throttle. Maybe I'm stating the obvious,
but that log could be on or off boost, part or mid throttle, stoplight to stoplight, or freeway run up to boost and off again.

I aways did runs on the freeway, in fourth gear, press record off throttle at 2k rpm or close to. Press record again at redline and let off the throttle. At least then you know what gear and can assume boost pressure and when it occurred.

wcc · 02:51 PM

How did you get the graph to 1sec intervals instead of 5?

All of those sessions were from a stand still. Redlining in all gears, maybe not all of third, but not 4th at all. I think the first session 3rd wasn't run out so I don't think that one is any good. The other sessions I ran it all the way through 3rd. Lets just wait till I get that RPM kit and I'll get some new data.

So with this RPM kit will I be able to tell shift points and what gear I'm in for a full run from 1-3rd or do I need to make one session for 1st, one for 2nd, and one for 3rd?

mark '87 930 · mark '87 930's Garage

Bill, the RPM kit will add an additional line of date to your graph. So you'll see what RPM you are at in relation to the AFR reading. I bought one as well (with the RPM kit) and glad I did.. more so because it's fun to play with and check you're not running too much in either direction.

jbrinkley · 10-14-2008, 04:31 PM

you click the magnifying + thing and then hover over the time marks and click.

wcc · 10-16-2008, 02:50 PM

Ok, just messing around tonight with the equipment I still have and I recorded a couple sessions with just a second gear run and after a little tweaking for those runs I have it set now in the low 11s. It really doesn't take much of turning that screw for adjustments. So, is low 11s on boost too rich or can I just leave it as is? I'm going to re-check it all when I get the RPM kit here. Hopefully by the weekend.

Shadetree930 · 10-16-2008, 04:53 PM

Quote:

Originally Posted by wcc

Ok, just messing around tonight with the equipment I still have and I recorded a couple sessions with just a second gear run and after a little tweaking for those runs I have it set now in the low 11s. It really doesn't take much of turning that screw for adjustments. So, is low 11s on boost too rich or can I just leave it as is? I'm going to re-check it all when I get the RPM kit here. Hopefully by the weekend.

What screw are you turning on which part of the engine to set your AFRs to mid-elevens?

wcc · 10-16-2008, 05:20 PM

The allen head screw between the air box and the fuel head. You put the wrench in and it's spring loaded so you have to push it down GENTLY and you can turn it. Clockwise Richens it and Counterclockwise Leans it. I don't have a pic and I think it's a 3mm allen wrench. Next time I'm in there I'll take a photo or I'm sure there's one on here somewhere if you search. Hope that helps ya....

jwasbury · 10-16-2008, 05:36 PM

AFAIK the mixture screw is for idle adjustment and may have some impact at part throttle, but I don't think that you can adjust your full-boost WOT afr that way. You need to make those adjustments by changing control pressure with the WUR.

wcc · 10-16-2008, 05:47 PM

Quote:

Originally Posted by jwasbury

AFAIK the mixture screw is for idle adjustment and may have some impact at part throttle, but I don't think that you can adjust your full-boost WOT afr that way. You need to make those adjustments by changing control pressure with the WUR.

I'm sure many people will correct me if I'm wrong, but I think it does. I mean I've checked timing, adjusted the idle, then I set the mixture at idle. If your CI 'System' is working correctly it 'should' adjust the AFR as the RPMs increase. This OBVIOUSLY made a difference because I was just north of 12s AFR and now I'm low to mid 11s WOT.

Shadetree930 · 10-17-2008, 04:33 AM

Quote:

Originally Posted by wcc

The allen head screw between the air box and the fuel head. You put the wrench in and it's spring loaded so you have to push it down GENTLY and you can turn it. Clockwise Richens it and Counterclockwise Leans it. I don't have a pic and I think it's a 3mm allen wrench. Next time I'm in there I'll take a photo or I'm sure there's one on here somewhere if you search. Hope that helps ya....

Ah, I know the screw you are talking about. That would adjust mixture across the entire spectrum, yes? I was thinking you wanted to adjust mixture just during the early 'boost dump' when these normally go a little rich.

NathanUK · NathanUK's Garage

If adjusting that screw puts your idle CO out then you will have to reset the idle CO & then adjust the WUR.