Single channel O2

[Ed Wright]

Frank, when you play your log back, if you will pull up your fuel map, put it at the top, make it about half the screen size, then the log at the bottom, when you click the left arrow to scroll through it, there will be a "bubble" appear on the cell the ECU is looking at as you scroll through it. I don’t use load indexed speed density, that always goes to the top row, just like AlphaN. I mean regular speed density, Baro changes your manifold vacuum and MAP values. Load indexed will not. May as well use AlphaN as that, imho. On the dyno all you can do is tune for the weather that day. The Great Bend Kansas points race recently is the first time mine has used the 3rd row down in the map. Start out with 2% difference per row, dropping as you go down, in the top 3 or 4 rows of the fuel map for a starting place. Won't be all that far off. When you tune in different air, just tune the row at which it's looking. Your numbers will be bigger around the torque peak. That is normal. Leave the already tuned cells alone. Then log driving down the return road, with it warmed up. Shoot for about 14-1 to 14.5-1 there. Mine likes to leave in the mid-12s. Yours may be different. The return road tuning should also apply to AlphaN. That part can be done on a variable load dyno. A couple of feet of collector extension will make idle and low speed tuning accurate. Open collector will causes bogus lean numbers. Might look right, but hardly ever are.

[Signman]

Thanks Ed

Am using the data log as you say. One mistake have been making is tuning top 4 rows together. Same number stacked in each RPM cell. Not giving it a chance to tune itself.

The initial load at launch as tried to describe above has to be affecting my 300 #s as it is going very lean - very fat - very lean and then to target AF ratio. The only time it sees this RPM range (2500 - 5000) is at launch. With this converter never below 5050 in the worst air in any other gear.

[Ed Wright]

Frank, leave from a very low RPM to get a better look and more launch data. Footbraking, you can leave from an idle, if the initial rich spot moves or leaves you were seeing A.E. (like accelerator pump) fuel, so ignore that. Starting lower than you will ever leave racing will allow you to clean it up better.
In AlphaN mode the top three or four rows would be the same.

Good luck, Ed

[Signman]

Thanks Ed!!

[Adger Smith]

I was talking to one of my buddies at Comp about this thread and got this e-mail from him. Since it is Comp's policy that employees don't get involved with internet forums I hope I don't get him in trouble by posting it for all to see. I thought it was good info.

Quote:
You might want to suggest to Michael that if he is running in Alpha-N, he needs to try his program in open loop. Alpha-N ties the ECU to the TPS and tunes more like a carburetor that way without influence by the O2. Then use the O2 to track the results and make changes to his fuel map. Most of the Super Stockers I know of do not hesitate to go into the 13:1+ range with no damage. The Comp cars are forced into the 12.5-12.8 range because of the compression, but where there is very little………….

Also, there is a FAST option right in the catalog that is Digital Air/Fuel Meter RPM Module (part number 170536) that allows engine RPM to overlay the A/F ratio readings with an existing or new single or dual A/F meter during playback. "End Quote"

I hope this can help.....

[Ed Wright]

I hope Michael is not trying to run his in Closed Loop. If he is I missed that part. Might sound like a cool idea, but I have yet seen one run as quick or consistent as in open loop. I tried that also. It was constantly chasing it's tail. I don't think the ECU can make corrections fast enough for a decently quick race car. Everytime I've put someone's car in open loop it has picked up. Some guys just can't accept that, and insist it has to be better "because it always corrects it's self". About like drive by wire is better. LOL

[Michael Beard]

I just have it in closed loop in these early stages while I try to get the fuel map in the ballpark. At least if I get it too lean, it tries to richen it back up toward the Target A/F so I'm less likely to hurt something. I actually got things pretty close to where I wanted them at Maryland last week. Once I'm comfy with my general setup, I'll go back to open loop.

My biggest question marks currently are around the driveability/staging/launch area. Right now it's reading lean driving around the pits, real rich around launch in order to cover up any launch stumble (I know this really needs to be done rather with the acceleration enrichment deal, but I need to gain a better understanding of its use in practice. I understand that it's like an accelrator pump shot, but like everything else, I'm just trying to get a handle on what the numbers mean and "how much is how much?").

I've done a little reading in different forums, and seems like they're saying I should be around 14.5 or so driving around the pits (low TPS, low rpm). I've heard some people say they've got it CRAZY lean at launch rpm (doesn't sound like a good idea to me, don't want to hurt something), and others say a hair on the rich side (12.5). Again, as far as downtrack performance, this thing just flat hits a wall at 13.3 and won't get out of its own way unless I richen it up. In total, this thing just gobbles fuel.

Oh, one other (unrelated?) issue I'm having is that about once every 8-10 starts, the starter's kicking back. Never did that with the old motor, and all the other times, it fires right up almost instantly.

I don't have internal logging set up just yet, but have logged some runs via the laptop in testing.