tuning a c5 corvette with B4307 issues

[louis]

I have same corvette with diff mods and never saw this one before.

For the map I ran calc airflow rate grams/s in data tab. In the column I ran rpm and in the row tab I ran ect

I get a scan log and paste it into B4307 and all of a sudden I have huge startup idle, idle hanging, cruise effect etc.

I can cut this table in half and all is well again. He is running a 90 mm tb and set B4349 to .0191.

I can get him a good tune like this but if the computer says desired air it wants and I cut it in half to make it work, would it be better to stick with the desired air it wants and readjust everything around it? I am just worried if I do it this way I will be chasing my tail for all the issues above. Easiest fix for me was to adjust B4307 till all those issues disappeared.

Anyone have an opinion on the procedure here? It seems I am coming up with the same end results... nice afr steady idle no cruise effect.

[WeathermanShawn]

For the map I ran calc airflow rate grams/s in data tab.

Never heard of using calc airflow rate for B4307.

Normally Desired Airflow is computed using the Idle STIT's and LTIT's (RAFIG, RAFPN) as described here:http://forum.efilive.com/showthread.php?4661-Idle-Tuning-Helpful-Info-Inside

I have had success setting B4307 using MAF Airflow g/s plotted against ECT. I describe that process here:http://forum.efilive.com/showthread.php?14439-Idle-Tips-amp-Tricks

Bottom line is an accurate Idle Airflow as obviously it effects many other functions. I have never used calc airflow rate in the manner you described. The two I mention above have given very accurate Desired Airflow values.

Good luck.

[louis]

Thank you for the reply. I did make a typo in the 4307 table. I used calc airflow rate grams/s in data tab. In the column I ran calc airflow rate grams/s (dynair)and in the row tab I ran ect.

I should have also stated it was a sd maffless tune and I did find the issue. The lc-1 wb voltage was off and once set up properly the wb and efilive stoich numbers synced in very well. It was kind of hard to tell which numbers to go with. The efilive logs for stoich or the lc-1 meter. I went with the efilive logs and once I adjusted the voltage on the lc-1 and all fell into place after that.

One thing I did notice though that was odd to me is the tune takes about 20 min to settle in to the commanded afr. Starts out a little lean then fattens up to commanded after about 20 min of driving.

I will be tuning this 20 min delay but would like to know a good place to start. I am not running any stft or ltft at all till I get it dialed in and he will stay in sd maffless config. I looked everywhere to figure out what is adding fuel but could not find it. For the moment it was easier to increase the target afr toward a little lean in idle areas till I locate what is making the changes after 20 min. This is a 2002 c5 corvette

[WeathermanShawn]

Glad to hear you got most of it figured out.

Now it all makes sense you were logging DYNAIR with a SD Mafless-Tune..

Good luck..