Hi,
I finally put my car back together and I am trying to do some VE learns with an LC1 wideband and EBL. Then engine runs a little rough in open loop and doesn't seem to improve much after a few VE learns. It does start surging if a tap the throttle. Do I have a vacuum leaK or something else?

 

It could be a vacuum leak, it could also be the tune. I usually start with doing VE learns in closed loop BLM mode. But as long as the car is driveable in open loop then no issues with going WB mode right off.

As for being rough, which heads are on the engine? Roughness is a sign of too much spark advance. Make sure that the "SA - Initial SA" in the calibration matches the distributor base timing.

RBob.

 

RBob
Thanks for the quick reply. I have vortec heads with a zz4 cam with the ramjet intake manifold, which is a pretty mild setup. I found a defective distributor cap, where the center button contacting the rotor was damaged. It idles better.
I will verify the timing again and try to tune in closed loop BLM modes.
Just a quick question concerning the EBL. The WB data is used only by the EBL during VE learns, but not during normal operation. No changes are actually made to the bin until it is flashed to ECU. So you will see improvements after VE learns when the new bin is flashed. I am very happy with the EBL thus far, but was a little confused about the overall process.

 

I've had past surging idles issues as well.
Upon recommendation of fellow members , I changes two things significantly which helped.

At the target idle RPM speed on both my fuel and spark charts, I had to make sure there was very minimal change going to the next few boxes in any direction. I had to smooth my data points so there was less of a slope from point to point in any direction of change of rpm or kpa.


For fuel, I'm idling at 800rpm at 60kpa, all those cells are nearly the same amount. Essentially, it created a "bowl" for the idle to sit in. Instead of seeing lots of fuel and spark changes over small change increments of rpm or kpa that cause the surge, it sees relatively no change at all in my target area.( at least in this case).
There is a "flat spot" in my spark chart as well, but not so extensive.


Although I would anticipate this is not the only strategy that could prove useful, nor perhaps not the best one, it seems to help my engine immensely. It now has a very smooth flat idle, and with a recently added wideband O2 sniffer, I've also seen the need to cut a lot of fuel at idle and was able to get rid of much "Stinky" as well. (I've been surprised at how little fuel it needed on the Low rpm fuel table as a whole)

Consider looking into threads on Throttle Follower issues as well.

TPI'd 400 block, 230/236 Comp Cam 1.6 rockers, 58mm TB, SLP siamesed plenum, Edelbrock hi-flow manifold, (TUnerpro RT using S-AUJP_v4)

 

There is a calibration included that has the main and extended SA tables from a Vortec truck calibration. Can copy those over via the compare feature of Tuner Pro.

Yes, that is correct. Until the new calibration is flashed in no changes are made at the ECM.

RBob.

 

Question for Lakeffectw: I've got a "stink" problem too.
So, if I understand correctly you made the 9 cells under "SPARK ADV MAIN" surrounding your 800 rpm vs 60 kpa the same?
And you also matched the 9 cells surrounding the same point in the VE Lower Table?
And this helped minimize the "stink" problem, AND improved your idle?

 

I just edited my original comments as I now see how the statement was confusing. The fuel table "bowl" absolutely exists in my lower table. I would now point out two things I realized for my setup..

1) In general, I'm also finding the entire slope of the lower fuel table hill from 10-100 kpa and 400-1600rpm is turning out to be no where near as aggressive or steep as I originally thought it should be. That lesser slope is slowly being extended into the upper fuel table to about 2000rpm, but I'm being much more cautious in cutting there, (so far) and will likely keep the top end of the chart more on the rich side, not lean.

2) Overall, I think the surging was caused by seeing vastly different fueling and spark data once off the desired point. Too much change from one point to the next! Backing out of the driveway or going down a side street at 1200 rpm really doesn't need much more in the way of fuel or spark than did sitting in my driveway or at a stop light.
The flat spot for timing is much smaller, but keeps the same idea going, as to not provide additional timing so that it drifts away from my desired idle point.

The "idle bowl" concept works real well for me, as there is little additional timing or fuel in surrounding data points to make it drift or surge from my commanded idle speed. It's very smooth.

I'm beginning to see now that the "bowl" worked because the rest of the chart was too aggressive anyway. I'm being to realize that now, so that the bowl is getting wider all the time. The edges of the bowl get extended further out as I continue to cut unneeded fuel in other areas of overly rich fuel charts. It's surprising how flat it's getting compared to the shape of my original fuel mountain.

My gas mileage has been increasing as well. I've gone from a sickening 8.5mph up to 10.1, over 20% better. I think I can hit at least 12. (450 horsepower)