Havent posted here in awhile , been busy doing honest to *** fuel curve and timing tuning :-) this has been one of the best investments i think ive ever made for my fleet :-)

well here the quickie on the setup im running in my formula:
lt4 hotcam 218/228 w/ .525 lift
vortec heads mildly ported
vortec tpi intake
SLP runnners (ported)
slp headers 1 3/4
vigilante stall 2800(stalls at 2600 on stock engines) give or take
and the obligatory 730 ecm :-) lol

My first problem im having is , i believe related to the second lesser problem.........my idle blm's run about 122-126 range and ive left them on the rich side with the understanding that will tend to smooth an idle out some. my timing in this region is 28 degrees. Im attempting to get her to idle as smoothly as possible at 700 rpm. i just cant seem to quite tame the lope and the rpm fluctuate less so when she is hot (ie. traffic) and my iac counts are about 7 or so when warmed up fully.
The other annoyance im having difficulty tracking down is a decent cam surge most noticeable in the 1000- 1300 rpm range when lightly getting on the throttle(again as in traffic/stoplites) ive narrowed down the rpm region it occurs in but am getting stuck as far as how to eliminate it or minimize it further.

The other major problem i seem to be having is grasping the TTC unlock/lock tables and exactly what the TPS% means? does it have to see that much of a throttle change? has to see that value and will lock up over that point? or does it only lock up under that point? My TC locks up at 45mph and is quite acceptable now that the fuel and timing tables are being dialed in(slowly but surely). but it is acceptable at lite throttle only obvioulsy any higher throttle and its like hitting another gear and very noticeable....and if anyone can answer this 100% i would most appreciate an example to make sure im understanding it correctly..

I have searched the dyi prom board thru tons of posts and printed the majority of them but the only TCC table related ones(that people said to look at) i could find were dead links and for some reason i cannot access the archives so if there is a post out there if u could give me a good link or email it to me i would be most appreciative. the same applies for the idle and cam surge questions/ problems i am having (got two binders one is posts and the other is the $8d hack which im still trying to make sense of).

thank you
Jeremy

 

I know that the TCC tables are kinda voodoo science. At least for me they were.

It came down to moving the "window" of TCC lockup down so that it would only lock when I was cruising. Anything under or over and it will unlock. For 4th gear I added a slightly larger margin for the upper unlock range because my engine makes alot of low-end power and it can lug down to 1500 rpm and still be live-able.

 

heres some reading on TCC function. should help demistify the topic a bit.

http://www.diy-efi.org/gmecm/papers/tcc.txt

if that doenst help post agian. as for your rpm surge whats the map reading like ??? is the vacum spiking ?? or is it just lean ?

 

timing seems to be steady , but lower than other areas that arent affected so i may start playing there again to see what changes i can make to smooth it out .


The Blm tends to stay fairly steady around 124-126 during the surging

The map(kpa) seems to fluctuate more than anyhing else from the mid 40's to low 50's as the surging occurs............

so any input u can lend by all means feel free :-)
thanks
jeremy

 

doh forgot about the tcc temporarily grrrrrrrrrrrrr :-)

im beginning to understand it better but i havent quite made it all out yet(i think i run on fuzzy logic)

If someone would be so kind as to give me an example? that way i can directly relate it to what im trying/attempting to do...

im using the aujp as a base and the car does lock up fine at 45 and lite cruise/throttle fine but anything over that and its like another gear... having trouble understanding just what it is that i have to do in relation to the lock/unlock tables in tc

Im trying to make it engage very lite throttle and hold off locking under harder acceleration until higher up in the powerband/mph

thanks again

 

ill look around the $8d file and see what i can come up with to help with the TCC lokup params.as for the map surging. try doubling the length of the vacum hose. see if that helps. could be a spot in the rpm range where theres alot of reversion. doubling the length of the vacum hose will mask the reversion. also using a small vacum resivor will help to.