Wild and crazy EAE behavior

[cmonref]

Have been tuning EAE for several weeks now and am pleased with the drivability that has resulted. I’ve tried to integrate small pump AE values, added CL Idle, and tried EGO Control all with generally good results. Each needs more work, but things are looking quite good.

So today, I turned pump AE and EGO Control off and wanted to see the performance of EAE in regular driving plus some contrived situations. Before the drive, I raised the ATW and SFW kpa curves at the top ends to smooth the curves that I had been working with.

Then … at ~4200 RPM with a smooth throttle increase, after a couple of seconds severe jerkiness occurred. It happened several times, each time at 90+ kpa and ~4400 RPM. Backing off returned the engine to smooth running.

Attached are the MSQ for the run and an MSL extract that includes the time periods mentioned below. The events at time 663-664 are pictured and described below.

At 663-664, throttle increase produced MAPdot and TPSdot values but no reaction in EAE. At 664.336, EAE and PW jump up together with WallFuel right behind increasing from ~20,000 to over 460,000. (I had never seen WF more than ~90,000 in tuning.)

Same thing at 668, with multiple spikes of EAE and PW with PW going to 0 four times and WF going over 650,000. Back off the throttle at 670 and the engine runs normally.

Similar conditions at 667 did NOT produce any anomaly. But the same wild sequence occurred again at 699, 720 and 771.

I cannot see any initiating events that would have caused EAE to behave as experienced today. What I do know, is that before this drive and log, I smoothed the ATW and SFW kpa curves at their top ends, ending with values of 79% and 23% respectively at 100 kpa. Those full EAE curves can be seen in the MSQ.

Anybody have any insight as to what happened and what caused it?

Brian

Wild EAE.JPG

[cmonref]

Today lowered the high points of both ATW and SFW kpa curves to the values used prior to two days ago. ATW max 71, SFW max 20 at 100 kpa. The engine did NOT miss at any RPM up to 5500+ which has been my experience for quite some time.

Raised the ATW and SFW kpa curves back to 79 and 23.1 as described in the original post. Tested again and ran into the same erratic behavior as yesterday at ~4300-odd RPM with very high TPS and MAP.

If it hurts, the doctor will tell you "don't do it." So I'm going back to the lower ATW/SFW values, even tho' the curve looks "funny" at the top end as it turns horizonal. The only discernible difference in driveability is the negative aspects of the higher EAE values that apparently cross some mathematical line and create erratic behavior in the EAE algorithm.

Both ATW and SFW curves are much higher than the default curves -- but that is where the tuning took them. But there is apparently the danger that a high limit can be exceeded with erratic results.

Brian

[mrx79]

Even if the post is somewhat older... i would like to know if the rootcause was found?
and if so, if the MS2 code has the same "problem"?

At least if there is no fix, it would be good to know where the limit is which causes that issue.

Thanks

[muythaibxr]

Most likely there was an overflow of some sort in one of the calcs though I have not tried to reproduce the problem. I'll have a look sometime and see if I can make it happen on the bench.

Ken