2001 S10 4.3 Vortec Blazer Surges at idle after starting when hot

[gnnova]

I have a 2001 S10 4.3 Blazer that has an issue with a surging idle after it is has been driven, shut off and allowed to set for 30-45 minutes. It has a factory cam that was used in the 94 Blazers that has more lift and duration than the cam it came with but I don't have the exact specs. It will clear up after 30 to 60 sec and idle fine. Shorter off times or longer times off after the drive is ok, although it does idle a little lean but not as lean as when it is surging. If it is started and driven, the idle VE will show it 5 to 6 % rich. This lean condition and surging is only after a restart after it is driven for 30minutes or more. I have tried increasing the Afterstart Friction and Airflow Delay's 5 to 10 cam revolutions in the effected temp range and it has helped. It seems like I am going in the wrong direction if it it is already idling lean. If someone could give me some insight on this, it would be appreciated
2001 Blazer idle sca a 6-12-25.hpl2001 Blazer criuse sca b 6-12-25.hpl2001 Blazer increased Startup PID delay time Added Cam rotations to airflow delay 6-11-25.hpt

[gnnova]

I forgot to add a scan where it was surging

2001 Blazer idle surging scan 6-3-25.hpl

[Vbb1994]

I'll have to look at the log when I get home ,as I'm on vacation but is there a chance you've got an exhaust leak that could affect the o2 readings only when the engine is hot?

[gnnova]

There is no exhaust leak I can hear or see. I found something last night that may be an issue, the Cylinder Charge Temperature is set to Disable. If I am correct, the PCM uses this calculation based off of the ECT and IAT for fuel and timing. I'm going to Enable it and see what happens. Probably going to have to redo my VE and MAF tables again. That is OK if it fixes the problem.

[gnnova]

Well I set the Cylinder Charge Temp to enable. It did not fix my issue with surging after start but it feels like I have more power in the light load/cruising area. This also leaned out me VE table 2 to 3 percent most everywhere so now I need to redo my VE table. I did look at my Hotsoak Enrichment table, it is set to zeros everywhere so I will try adding some numbers in the effected temp/time area next after I get my VE table back in. More to come.

[gnnova]

I think I have my issue resolved. After several scans, I found that my issue was not only happening after several minutes but another detail was that is was only 10 to 20 seconds into the after start idle that the surging would start. So after trying several of the settings in After Start which is in Fuel-Cold/Warmup and Fuel-Misc-PN/Drive Enrichment, the section that is Decay Step seam to be the area to modify. What I did, was change my REVS settings from 176deg and higher, to 120revs from 0-9revs. Seamed like a lot, but from what I have read, this section effects the number of revolutions between each decay step down. So it should extend the time of after start enrichment, since my lean issue was happening 10-20 seconds after starting. So far this setting has fixed my issue but I need to drive it more to say for sure that it has.