Idle Surge when tuning VE

[domestic rice]

Can Anyone figure out why this thing is surging like it is. The base idle was nice and smooth. then I tried to tune the VE and ever since I swapped stuff over to do so it gets up to temp and surges till it stalls.

[Mez]

1. Make sure the spark over & underspeed tables are stock.

2. The VE table is very rough. Set it back to stock and, perhaps, reduce the lower rpm cells 20% to start and tune from there.

3. Both the Idle spark tables are high and not smooth. Put the idle spark tables back to stock then add 4 degrees to the whole table. Reason: With the idle tables set high and not smooth, the engine torque will be erratic resulting in the idle RPM to be erratic. Also, a higher idle timing makes it more difficult for the spark over and under speed tables to keep the RPM under control because a small change in timing makes a big difference in torque. Lower idle tables gives the spark over and under speed tables room to do their job.

4. Put the high & low octane tables back to stock in lower RPM and g/cyl cells.

[Asylumwarp]

notice everyone keeps saying go back stock? I just noticed these are newer than my last tunes/scans i've followed and see your iac counts now.. Which i think are still high. BUT i noticed, look at how lean it goes right as it starts its loping/hunting. Your idle overspeed table is setup, maybe you should zero that table out as well, so when it hunts upward, it doesnt change the timing either.

[gn2beatu]

I wouldnt recomend zeroing that table like asylumwarp said. Just fix the issue so the computer can maintain the idle you want with the over/under adjustments.

[domestic rice]

It was a little ruff start, idled decent in mid range then once again once it gets up to temp (~190) it starts with the surging.

[Mez]

notice everyone keeps saying go back stock? I just noticed these are newer than my last tunes/scans i've followed and see your iac counts now.. Which i think are still high. BUT i noticed, look at how lean it goes right as it starts its loping/hunting. Your idle overspeed table is setup, maybe you should zero that table out as well, so when it hunts upward, it doesnt change the timing either.

Your idle spark tables are way too high. Subtract 12 degrees from both tables. Set the idle timing tables between 15-20 degrees below 1200 rpm. There is no reason to have them in the upper 20's degree range. Maximum torque is not the goal. A stable idle is. If rpm oscillates up and down then dies, then you have a MAF/VE calibration problem and not spark.

When idle spark is set that high, the idle RPM becomes hyper sensitive to very small air or spark change because they are near he maximum torque point. Its a knife edge. A lower idle timing gives the over and under speed spark tables room to do their job. This is not just me telling you this...its has been stated by the experts. Your high/low octane spark tables are fine but still a little rough in the idle area. Look at the .24 g/cyl line. Its higher than the .20 g/cyl. Smooth it out.

The idle over and under speed spark tables only help stabilize the RPM in the idle area but they won't fix a bad VE and MAF table. I believe the root problem is in those two tables and no matter how much you mess with the idle spark tables and the over and under speed spark tables, it won't idle right.

Some times, you have to start over with the stock tables because you've jacked up the other tables too much.

[domestic rice]

I did out the tables back to stock in that last log/tune I posted. It's still doing it. I did leave the tranny and gear setting as I had them though, since the trans. Appears to be shifting alright as of now.