greggbruce

iTrader: (1)

Heya all, sorry for the long initial post, but I feel I'm turning circles, and have started over 4 times now, so here's some explaining up front
Got this 91 vette , friend just purchased it at auction, he was told it has lingenfelter stuff (no documentation, and a phone call to lingenfelter says cars that old they can't verify, only kept records by original customer name). It has a superram (I think, great big box on top of intake), 58mm bbk throttle body, long tube headers, nice high stall torque converter, and roller rockers (that were all set to more than zero lash and rattling badly). Thought this might be causing knock sensor to pull timing and start this thing to surging idle -- yeah, adjusting them to be quiet made no change in idle surge. (brand new IAC) Found it has stock chip, AXCR and the few times the idle doesn't surge, it's at 50-55 kpa MAP (guessing it has a non stock camshaft, but it doesn't sound that radical) I have done some HP Tuner work with newer vehicles with a LOT of mods, and have had great success adding some timing and air, but I have burned over 25 proms worth of revisions for this thing (Tuner pro RT v5), it makes things a little better, but not fixed. There are quite a few tables and scalars that make no sense to me (do they ADD to or subtract from a table?) or even better, what freakin table are they modifying? I have commanded the idle to 1500 rpm and it just plain refuses to do it. I have commanded the SA to 40 and it refuses to do it -- but then I'm finding there's tables that modify tables that modify tables - is there some sort of hierarchy list that shows what modifies what? I thought I had this thing nailed when I found a post https://www.thirdgen.org/forums/diy-...k-neutral.html talking about changing this value -- stock was 1.0 -- I changed it to .5 and everything seemed fantastic -- no more surge, no more stalling going into gear, no more stall when ac came on -- but by this time it was almost at operating temp. With that tune though, it won't hardly start cold.... backfires, dies etc. (and that's the only change I made to that revision) So I put the previous tune back into it and noticed now the cooling fan comes on with the key on-- I am wondering if the chip itself has freaked out (after erasing and reprogramming 25+ times...) or if the computer is taking a dump or what. Now the only tune/chip that doesn't make the fan come on with the key on is the stock one --

some of the parameters that make no sense to me are:
IAC COMMAND SPEED OPEN LOOP OFFSET -- offset from what? zero idle speed? why would I want to offset the OL speed? there's already tables set for temp/speed ...?
BASE COOLANT ADVANCE CORRECTION TABLE BIAS -- this infers there's a need to look at timing differently and that it can even be wrong and needs correction? why does it need a bias to change?
OPEN LOOP CHANGE TO FUEL/AIR VS. MAP again, does this add to or take away from?
IDLE SPEED TIMEOUT VS. COOLANT TEMP -- how can idle speed TIMEOUT? And then there's some DECAY table....
START UP SPARK ADV VS. COOLANT TEMP again, does this add to or take away from?
FORCE BLM IDLE CELL CCP %DC THRESHOLD -- why would I want to FORCE the blm idle cell in the first place? wouldn't it just be easier to eliminate ccp at idle?
and why would I want to ADD TO IDLE IN P/N ? I would think you would want to take away from idle speed in P/N cuz there's less load....
... there's more, but I quit writing them down, feeling overwhelmed at this point.

Watching the datastream (when I can get a good one -- sometimes it's just all over the place with values that can't even be real (ccm interference?)) it just looks like the MAP starts climbing for no reason, then idle falls, falls, SA comes up, idle still falls, IAC comes up, idle stlll falls, still falls, then everything finally goes super high idle and does it all over again.

I have widened the idle deadband, disabled stall saver, cranked up the timing (including initial, this seemed to have helped the most so far) , extended time in open loop, leaned the idle portion of the ve table (made the exhaust more tolerable), tried changing the IAC counts multiplier, and a myriad of other seemingly idle related things with no concrete success. I have started over from stock tune 4 times trying different things and it all seems to make not much difference....
I would like to make cold idle/ start up better to start with, then can go on to closed loop
-- thought I had it at one point, cold was good, but as soon as closed loop happened, it all went haywire... but I can only get so many room temp startups in one day to check the tune.
Now I have so many different files, I don't even remember which one was best at this point, I tried writing it down, but miss too many things getting excited/ disappointed in a specific file, I forget to take notes...
I have checked all the basics I can think of, has new plugs, cap and rotor, O2 sensor, no vacuum leaks, good fuel pressure, good compression, clean throttle body, etc.
got the IAC counts to 20 and above, but I'm thinking the o2 is not heating up well (brand new) -- just hovers around 450 until you drive it and get it smokin hot. (but should have nothing to do with cold start open loop)
Not too long ago I have been through the TunerPro Super$8D Manual , but that seems to be a broken link now and I don't have a copy of it....
Holy smokes, spent 3 more hours reading through the stickies -- found some good stuff, but still not sure where to start.
maybe from the beginning again.... looks like adjusting the "expected" AFR (or rather FAR in $8D) in closed loop -- or excuse me, changing the R/L threshold or something like that, I guess I need to read everything all over again. I can also post up the .bin and a datalog when I get back to it again in the next couple days.
Wondering if I should just plug in the S_AUJP_V4 and see if that works better...?

I am looking for the silver bullet, but realize it's gonna take more than a few to straighten it out, but not sure where to start and in which order to do things. Kind advice will be appreciated. Thx for reading all of this...

UPDATE: started with brand new blank verified chip this morning using only a stock bin with the modified field https://www.thirdgen.org/forums/diy-prom/743982-quick-tip-park-neutral.html ] fired up right away, no cooling fan with key on, no surging, even drove a block down the street, still idled good till I sat still in gear and blipped the throttle, then it died. But it seems this a step in the right direction. May try to change the value from .5 to .75 or even .25 and see what happens later today (stock prom is 1.0)
So I guess even with the chip offsets set correctly for 27fs512 and telling flash and burn to "erase chip" doesn't always come empty after "blank check" -- does that mean the chip is bad?
another question, both this AXCR and the S_AUJP_V4 bins show the cylinders count as zero why not 8?

greggbruce

iTrader: (1)

ok, finally figured out I have "fake" chips (27fs512)
http://support.moates.net/fake-27sf512-chips/
so after finding a real one -- got a new bin put in, and VIOLA !! idles perfect, won't die going into gear or when the fans come on !!!
just have to lean down the idle a bit (burns your eyes)
and it will be done!!!

So if things don't seem to be working right for you, check your chips !!!

I still wouldn't mind some answers to my questions in my first post if anyone knows, I would appreciate the knowledge..

84Elky

Will be glad to help if you are using $8d. But first it's necessary you update to S_AUJP v5 here : https://www.thirdgen.org/forums/diy-...ml#post5859341.; Why? Because so much has changed from prior releases. Note that the instructions will show how to load your existing calibration to S_AUJP without using any of the S-AUJP features. So all is as before. The reason for doing this is because the XDF is much better commented than other versions which will hopefully answer many of your questions. Press F2 using TunerPro to see any of the selected XDF item comments.

So once you update, ask your questions and will see if I can help. Two I can answer now:

1. Why is 100 RPM added going to P/N from in gear rather than other way around. Agree it makes no sense and It's complicated, but code is continually calculating the Desired (Commanded) RPM which is used to determine other idle characteristics. If a problem, can always adjust it downward, even to 0 if you like to eliminate surge going into P/N to see what happens. Every car is different. But know that going form P/N back to gear may cause a stumble transition form equal RPMs due to the increased load if in gear. GM for the most part knew what they were doing.
2. Why is # of cylinders for v8 = 0. Code is all in assembly. It is constantly checking to determine that the ECM returns 0x00 to ensure injectors will be fired correctly based on # of cylinders. The NETRES on the MEMCAL; is hard-coded to return 0x00 so the code must be compatible or get a Cylinder Select Error. Also, The 7730 ECM is designed to also run 4 and 6 cylinders which have other weird values, but each represents certain bits being set. Have to think hex and binary and not decimal. Just know 0 is the proper 8 cyl value.

One final thing. Because XDFs use varying descriptions, it's always good to use the hex location of the variable in the calibration to avoid any confusion. That value is available in TPro via F2 as described above.

HTH

greggbruce

iTrader: (1)

hey, thanks for the update -- it took me a while to even FIND the v4 bin.....
I will install this and see where it gets me, I've got cold start idle better, but still get intermittent surge and the exhaust makes your eyes water, can't seem to get it lean enough....