y5mgisi
1 ton status
By the looks of things going back threw my data loggs, my idle park map readings are averaging around 45kpa and idle in gear is averaging 55kpa. Near as i can tell.
By the looks of things going back threw my data loggs, my idle park map readings are averaging around 45kpa and idle in gear is averaging 55kpa. Near as i can tell.

Open: Not using O2 sensor. ECM is running the engine purely on chip settings with no adjustment from O2 sensor.
Closed:Useing O2 sensor feedback.
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You can advance the distibutor a few degrees to see if additional advance helps the idle Kpa. Usually the distributor is set to ZERO, so try setting the distributor to +2 or maybe +4. I'm thinking the additional advance will improve the idle Kpa to 40. Also make sure the IAC minimum air is set for 10 ~ 15 steps when the engine is warmed up.
dave w
Dave your right of course. But yesterday on a stock engine, I had my idle timing so high when I dropped it 2 degrees I picked up 2.5 Kpa 2 more and I lost it! Found the sweet spot.You can advance the distibutor a few degrees to see if additional advance helps the idle Kpa. Usually the distributor is set to ZERO, so try setting the distributor to +2 or maybe +4. I'm thinking the additional advance will improve the idle Kpa to 40. Also make sure the IAC minimum air is set for 10 ~ 15 steps when the engine is warmed up.
dave w

Here is a zip file of my latest data log. Its just me sitting in my driveway and occasionally putting it in gear and occasionally reveing it up a little. If you notice, the IAC steps are 8 from block 35-538. That just seems crazy to me!


IAC steps of about 8 look good to me!
I looked at your data log. I noticed the TPS is showing - negative numbers, whats up with that?
The BLM's are super rich mostly 105, 128 is ideal +/- 2 or 126 ~ 130. You've got work to do!
dave w
Just found this doing a little searching. Not specifically pretaining to this/us, but it has a few usefull bits in it.
http://www.gmcmidwestclassics.org/Web pages/Tuning the TBI.pdf
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Lost since page 3.
Bought a USB cable from OBD Diagnostics and I'm pretty sure I have everything downloaded. Laptop in truck, opened Tunerpro and this is what I see
View attachment 120565
Even if it looked like the instructions posted here i still don't know what to do with Tunerpro. Do I just plug in, drive and log data?
After reading through this thread, especially post #68, I'm completely lost and in over my head and I don't want to be screwing with this thing every day. The first post makes it seem like you're a fool if you don't do this. Well I'm a complete fool and am totally lost.
Learning to do something automotive, that's not in service manual will test someone patience! 
So I need to download TunerPro RT and pay $39. That's OK, I don't mind paying for someones hard work.
USB drivers were installed on the laptop @ Com6. Should I try to move them to Com4?
Tried to unzip that file but windows says "it cannot open that file, do i want to search the web to find the file that created it?"