Fuel injection? Open or Closed loop?

[pbp1]

Originally Posted by Darrel Goheen

More thoughts......

Since I most likely can't win a heads up based on performance I should quit worrying about getting every last hundredths of ET out of my cars. I should just get them tuned to where it's consistent and leave it alone. Agree?

Just my opinion, but unless you have marginal traction, the tune that makes the engine run at it's peak performance will be the most consistent.

I suggest that you clean up the drivability area of your fuel table, then either put it in Open Loop, or set the closed loop to turn on about 300 rpms above your converter flash RPM.

[Darrel Goheen]

Originally Posted by pbp1

Just my opinion, but unless you have marginal traction, the tune that makes the engine run at it's peak performance will be the most consistent.

I have never spun yet but I will be running on a normally not so well prepped track this Friday night. If it'll hook at this track I should be good.

Originally Posted by pbp1

I suggest that you clean up the drivability area of your fuel table, then either put it in Open Loop, or set the closed loop to turn on about 300 rpms above your converter flash RPM.

It sounds like OL will offer most consistency. Do you agree? Thanks again!

[Ed Wright]

Originally Posted by Darrel Goheen

I'm getting very little correction at WOT. I've tried shutting off closed loop but it barely runs in the pits then so I have to turn it back on. I just need to get that area tuned in OL. So if you go to say Denver would you turn CL back on for a couple passes or just select the whole table and take a percentage of fuel out? Do you save a tune for every track? In CL I think my launch AFR is way messed up because of 2 step. As soon as I launch it adds quite a bit of fuel. Here's my thought at this point and please correct me if I'm wrong. Footbrake a couple passes to get launch area AFR close, turn off CL and get pit area tuned and then slowly adjust AFR according to data log? Racing gets critical now starting with Topeka Nationals.

Since those tracks pretty much have their own row in my fuel table, I run the same tune all the time. I use the FAST logger, play it back while I have the tune I'm running fuel table open, click higher RPM, it highlights the cell it is using. I only tweak that cell. The others are corrected at tracks where the Baro The top 4 rows in my VE table are: 102,98,96,90 KPA. Everywhere I have been uses one of those four rows at WOT. My vertical columns (RPM) are in 500 RPM increments. I never have to screw with my FAST XFI ECU anymore.
I would work on my idle and part throttle. I like my plugs clean.

[Darrel Goheen]

Thanks again Ed and to all of you. I really do appreciate all the help!

[Ed Wright]

Originally Posted by Darrel Goheen

Thanks again Ed and to all of you. I really do appreciate all the help!

Darrel, you can set the minimum RPM for Closed Loop high enough to only function at WOT until you get your idle and part throttle. If your O2 sensor in in the collector, closed loop can make your car very rich. Big cams with a lot of overlap will pull clean air in the collector, tricking your ECU into "thinking" it is running extremely lean, it will really pour the fuel to it to correct that perceived lean condition.
The 2 step has a similar effect. Misfires from the rev limiter put oxygen in the exhaust, which looks lean to the wideband & ECU as well.
Mine shows over 15-1 sitting on the starting line, on the 2 step. If in Closed Loop there, it gets so rich it won't leave. My converter flashed to 6200, air/fuel doesn't clean up until 6500/6600. I think it would be making false corrections below that. So, I can't enable Closed Loop until 7000. My VE table has 500 RPM breakpoints. I have worked on my fueling until it never makes over a one percent correction in Closed Loop now.
Might see what David says about this, but it has worked for me.

[Ed Wright]

Forgot to add: David (pretty sure it was David, I'm old) told me I should put my O2 sensor in a primary tube, for corrections from Idle & up.
I have since had mine on Patterson's dyno, with eight O2 sensors. I run mine in sequential mode, so I can correct each cylinder. Now, the sensor in one primary on each side should be fine. I had nearly a 5% spread between cylinders before. They are all very close to identical now.

After having run at all the tracks in our area, I log the first pass at each track now, never have had to touch it the last couple of years. Much simpler than running a carb.

[Darrel Goheen]

The Holley system will not allow closed loop on the 2 step. Closed loop happens at about 4500 rpm off the two step. My Camaro qualified better than usual in Denver but my Firebird wouldn't run the index today in Super Stock. Not sure if it's broke or I just don't have the tune right. I leaned it to 13.1 from 12.7 after 6000 rpm (per suggestion from Duane Dickens) for last qualifier in the morning so we'll see. Thanks again!

[Ed Wright]

13-1 is not lean at all "up there" at Denver. I would try 13.5-1. I'm surprised it likes 12.7-1 best at sea level. But, wide bands don't always give the same numbers. Be nice if they did. I bought a stand alone wide band set up so I could log both banks. Bought from the same people as the first. My original deal showed 12.9-1, the new one 12.5-1. Put it on Patterson's dyno with a wide band in each primary tube. Not that far off. Moved my original wide band to the other collector on the dyno. Both sides the same. In the car, one side still showed richer. Swapped sides with the original ECU wideband & the add-on, rich side moved too.

[Darrel Goheen]

I ran .03 under the index far enough yesterday morning in the last qualifying round after advancing the timing two degrees and leaning it out per Duane's suggestion. Why does does high altitude like a leaner AFR? I may try leaning it out more at this weekends race but it's tough to tell anything when you only get two time trials before eliminations. Thanks again Ed. I ain't giving up yet!

[Dwight Southerland]

Originally Posted by Darrel Goheen

I ran .03 under the index far enough yesterday morning in the last qualifying round after advancing the timing two degrees and leaning it out per Duane's suggestion. Why does does high altitude like a leaner AFR? I may try leaning it out more at this weekends race but it's tough to tell anything when you only get two time trials before eliminations. Thanks again Ed. I ain't giving up yet!

Less oxygen in the air.