Looking for cause of high idle in Datalog

[sgtbilkodle]

Hi,

Anyone willing to view my Tunerpro RT datalog and help me isolate the parameter(s) that might be affecting my park/neutral idle speed?

I have a 1988 Chevy R20 with 454 (7.4l).
TH400 3-speed auto tranny
ECM is 1227747 with AFTK chip originally
I have 27SF512 chip with Moates' switching adapter.
Engine is bare-bone stock

Problem: It idles at 900-1000 rpm in park or neutral. It seems to be fine (750-800) when in gear.

Things checked/done:
Replaced MAP, IAC, CTS, O2, intake manifold gaskets, throttle body gaskets, vacuum lines
Backprobed TPS and voltages were good
Performed IAC reset and baseline idle (throttle plate adjustment)
Timing is at 4 degrees BTDC at warm idle with ESC wire disconnected
Spent hours looking for vacuum leaks with various volatile aerosols
Replaced one fuel injector just to compare spray patterns.
Compared idle between 2 fuel pumps (I have dual tanks, each with their own pump)

What I have NOT done:
Not checked fuel pressure, but the spray patterns seem fine.

Other details:
Seems to have enough power.
I will attach a datalog
I noticed in the datalog recorded by Tunerpro RT that there is no spark advance but I clearly see a good bit of advance with my timing light when the ESC wire is disconnected, then back to 4 degrees BTDC when ESC wire is connected

[dave w]

The attached are the most current '7747 .adx and .xdl which has a patch to get the timing and fuel pulse width into the data log.

dave w

[sgtbilkodle]

Thanks Dave W. Being a newbie at it I'm wrapping my head around understanding the adx/xdf, what they do and which to use. I'll load them up, do a log and repost if that's what you're suggesting I do?

[dave w]

The .xdf is used to edit the .bin file (chip file).
The .adx is used to data log with.

You can use the patches in the .xdf file to edit the AFTK .bin file so the spark advance and injector pulse width will show up in the data log.

dave w

[sgtbilkodle]

Done, thanks. Now to get a day off to datalog! BTW, for highway spark advance, to add 2 degrees, which table do I adjust?
I see 2 very similar tables and I don't understand the difference:
"SA - HiWay Lean Cruise Spark Added"
"HiWay - HiWay Lean Cruise Spark Added"

[sgtbilkodle]

so here's a log file from today. I still get a little bit too much idle in park/neutral after driving. I'm looking for 750-800 rpm and its in the 900 range. Any ideas?

[sgtbilkodle]

So I finally figured out that the park/run IAC offset was too low and added a few steps. Now it idles at 765 regardless of gear selector position. I guess with it too low, the ECM was giving almost as much air in park/neutral as it was in drive, causing the park/neutral idle to be too high. I enjoy learning on my own, but sometimes a little bump in the right direction is helpful...
Please chime in if I'm misunderstanding how that offset was affecting things.

[JJK10]

Good Morning sgtbilkodle,
Could you go into more detail on how you corrected this issue? I've been having the same issue and everything I try doesn't help. Thank you, Jason