89 tbi350 idle issues

[hammertime371]

Ive been having some idleing issues with my k2500 tbi350. It seems if i set the tbi up as per the intitial set up thread it wants idle around 1000rpm. the tps and iac are in the correct ranges at this point. id like it to be more around 650. it slams in gear when idling at 1000. i see in the bin the c/l idle settings are set to 650 already. ive checked for vacum leaks but found none. if i back out the throttle blade screw it will then idle down to 650. in fact when the iac is set closed for intitial setup adjustment the engine will idle all the way down to 350-400 and stay running. any suggestions?

[FSJ Guy]

IIRC, it's recommended to set the throttle blades during the initial set up so that the engine idles at 100 rpm BELOW your target RPM. Since you want it to idle at 650, during the setup procedure with the IAC closed, set your throttle blades so that the engine idles at 550.

AFTER you have done that, plugged in the IAC and reset the computer, make sure you ADJUST your TPS. It sounds like the TPS may out of adjustment and the ECM thinks you have your foot resting on the gas pedal just ever so slightly.

[hammertime371]

tps shows .59 in tunerpro. i thinks thats fine right?... I adjusted the main spark table cause from 400-800 and 30-50 map the table cells were all set to 27.77. so i set them more progressive like the rest of the table is. that did seem to help as idle is smoother and it now idles more 850 without touching tbi at all. its vortec heads so not sure if what i did is a good idea.

[EagleMark]

.59 is fine. The reason for the block of cells all the same is for a more stable idle. Then it drops as accelerated before raising again 27.77 minus the warm bias is only like 17 at idle, then drops...

What spark table says and what is actually at timing marks is never the same, and differant in all bins, have to take in account all Spark Bias factors.

[hammertime371]

so i have the throttle blades set so i will idle at 500 with the iac closed. after i hook iac back up and reset ecu it still wants to idle at 1000. I find it odd that as soon as i plug in the autoprom to aldl port it idles down to 600. switching the switch the enables and disables aldl mode does change idle slightly. but when i unplug it idle goes up again.

[EagleMark]

It will idle higher until warmed up and closed loop... you sure it didn't go closed loop when you plugged the cable in? Plugging cable in with no 10k resister should do nothing, must be warmed up and closed loop before setting min air on throttle blades to 100 below CL idle setting. Then check IAC counts when warmed up CL. should be 20 to 40 counts.

[hammertime371]

i noticed that my iac wont go below 34 counts. tried another and its the same. should it go to 0 when its closed?