brettmc

96 lt1 t56 AI heads/cam. Using JET DST to tune with.

I have a problem with the IAC value going to zero coming to a stop. Of course at that point I'm still rolling, maybe 5-10 mph, and it wants to die. So what I have to do is heel and toe the throttle with the brake foot to keep it from dying. Usually a couple of quick stabs at the throttle and it'll idle fine at that stop. Then at the next stop the same thing. This is the only idle drivability issue I have.

Normally idles at 40 counts and has idled fine coming to a stop in the past. new iac unit in oct of last yr.
I can't figure out what needs to be changed in the idle constants and tables.

throttle follower iac vs mph
mph steps
0 30
4 30
8 30
12 30
16 30
20 1
24 1
28 5
32 5
36 5
40 5
44 5
48 5
52 5
56 5
60 5
64 5

tps iac offset vs rpm

this table is all zeros

SwampWS6

iTrader: (7)

Maybe a vaccum leak somewhere?

brettmc

would a vacuum leak cause the idle problem only when coming to a stop? I think a leak would manifest itself at all times.

also, i can see the iac count going to 0 in the log. that's when it will try to die. a little heel and toe action on the throttle and it idles fine.

moehorsepower

iTrader: (3)

is there an iac throttle follower with Jet? if so that is where you need to adjust

brettmc

Moe - there aren't that many idle tables...maybe 10. my tuning laptop is at home so I can't actually see the tune now but I did list the throttle follower iac vs mph in my first post.

do the offset tables add or subtract units listed in them?

moehorsepower

iTrader: (3)

Didnt notice, but dont worry so much about numbers, give the motor what it wants, I have had cars that would not idle correctly with the usual 30-40 count, but idled fine in the 50-60 range. either raise the steps a little or crack the TB open at very small incriments, like 1/4 turn, do only one thing at a time..