phase 2 is holley projection manifold with GM 454 TB. old cam 210/216@.05. new is 224/230 @.05 114 lsa. original bin from prior set up. prior FP is 12 now at 13. broke in cam today all OK. have not tuned it or run winaldl yet. it appears running rich at idle from exhaust pipes. will reapproach the VE tables as i am certain it is way rich down there. will be interesting to compare to prior values.
idle surges 600-800 pulses up/down with regularity. now i will assume the iac is the culprit. iac functioning per visual. appears seated 95% in CL. commanded idle in ecu at 700 rpms.
what if i command 600 and set throttle stop to idle at 700? unfortunately the iac will lose its functionality that way and last resort. will review the postings on this as i have anticipated this and saved pertanent posts.
no vac leaks. all new gaskets. using tunercat and i dont know hex . is is possble that cam will require me to run OL at idle? iac steps set to stock crossfire specs which i think are 1/2 of the dual TB steps? is the 454 pindle larger? i don think it is. have not yet seen cold start so cant comment.
ANY SUGGESTIONS? more chalanges ahead!

 

Hi Ron,
I have found the best way to tame a hunting idle is to adjust the Gain and Flowgain tables at 0x4A8 and 0x4C7 as per Bobs paper at diy-efi :http://www.diy-efi.org/gmecm/papers/747iac.txt

It may not fix yours, but its worth a try.

Now I know you use Tunercat, and you won't find these parameters there...
You do have access to them if you choose to use TunerPro. I use both, one for some tables, one for others..

 

thanks i have that paper in my tuning manual. guess tunerpro is in my future. also have not driven car yet. it may need the VE tables addressed as it is idleing in a diff cell(s). same with spark cells. will smooth that out and double check the commanded idle speed vs the 600-800 rpm it is idleing at currently. i would really like to know why this phenominon(sp) is occurring? maybe someone can explain. maybe related to diff cells as i explained. i will add same fuel/spark in each cell it is bouncing over. also i will check function of iac. i am not complety certain i have it wired correctly. i recd differing recommendations on the 1995 TB vs the wiring on the 1984. also GM truck manual apparently has an error as they label 1-2-3-4 iac wires as 1-2-3-3 !! what i do know it the pindle retracts when ign off and extends(95%??) when idle closed loop by visual. so winaldl will tell me if cold start and CL is wired correctly....

 

update. for reasons unk the surging stopped at CL after car ran on street. now it only surges on cold start 800-1500 rpms repeatedly. aggrevating. seems it wants to achieve high idle. exceeds it. drops it down too low(800) and spikes it back up. in fact if i drive it in OL and engine temps below 170F it may be a bit dangerous in city traffic. maybe i pull some of the iac cold steps out of bin? at least then it may surge 800-1000 or so.

 

Before you check the stuff for the idle, hows teh spark table look? Flatten all the areas around where you idle to one value and see if it cures it any. It may be a fueling thing, too.

 

thanks. will log winaldl on way home. drove car first time this PM. may be way under fueled up top. will reapproach ABC's on VE on the winaldl. will log moderate AE as well tonight.
it perked up. may be too fast? never could break tires free in first gear from 5 mph. can now.

 

TC has a TDF editor thats available. You can even use it for a period of time without paying for it.

 

update. it seems the car needed to be driven a bit. the idle in CL is fine holds 800 rpms nicely. i have commanded at 750 and i think reason it is 800 is iac in CL holds at 20-25 steps. i will reduce that (iac) when warm to 10 steps and that should drop CL idle to 750. the puter adjusted the BLM's(were lean) and car subsequently runs better. in fact much better. seeems the puter can work wonders. needed time to work its magic. will re-adjust VE and do a burn. now on cold start (choke) that surge is there. no big deal. will work on that. new cam is remarkably docile. smooth. car in barn for winter in a couple weeks. thank you.