ok yay yahoo my idle is completely random. it doesnt bounce, it doesnt stall... its just random.

i start the car, tap the gas... hovers around 1500 for a while, then drops to 1.
driving, coming to a light... slow down, stop. the idle could either sit around 1000, around 1200, or real low and horrible sounding (lots of vibration, sounds like its choking) at about 500 to 800.

i have, swapped out the old tps for one thats in spec. (no change)
cleaned the BAC very very well. (no change)
SET the new tps over and over and over again (its in spec. around .900 closed, 4.66 WOT)
played with that screw on top of the UIM billions of times (unless i have it too low [where it chokes and tries to die] its always the same)

no vacuum leaks, brand new silicone on everything.

any ideas? thats question 1.

question 2:

2 things that i dont know the factory setting for.
1) the idle screw on top of the uim. how far in/out is normal?
2) the throttle plate 'stop screw' (best i can explain it) its the screw with the nut on it that stops the linkage from closing all the way (havent touched that, but it might be wrong)

yea... thats it. i really wish i could fix this problem any help would be amazing.
thanks guys

tj

p.s. just so you know the specs:
1989 (s5) n/a gtu
streetport, 7k on rebuild.
all racing beat headers back (presilenced)
thats really the extent of the 'power mods' that would have anything to do with this.

manual tranny if that matters

edit: im thinking of buying an safc2 to fix this, but im stuck on that too because i dont want to (attempt feebly) to tune this car if its not already in spec. i hate bandaiding problems.

 

and no the cruise control cable isnt screwing everything up

 

Cruddy / dirty throttle body preventing throttle plates to close properly?
Clogged coolant passages doesn't allow cold start fast idle cam to disengage properly?


-Ted

 

ok a couple of things to go with this post, maybe you can help again ted...

i want to remove CSA (cold start assist) and everything that has to do with it. is it advisable? will it hurt anything?

also, the diaphragm that activates the secondary throttle plates... mine doesnt work. it never moves, although it can be moved by hand... i tried sucking on the line real hard, nothing.

now my cold idle had a surge, so today i thought that might be it from another post, so i unplugged the vac. line from the solenoid(?) that it comes from and goes to the diaphragm (on the back of the TB), and held my finger over the sucking hole. surge stopped. idled great...

can i remove that? i dont know what to search for to find decent writeups on these removals. anyone know of any anywhere? thanks!

tj

 

unplug the bac, wind out your thermowax adjustment so it's not doing anything, then see what the car idles at.

 

where is that? i havent played with any of my 'waxes' too much yet so i dont know which is which, and i really want to get this problem fixed :/

 

the manual and search function are both very useful things.
it's on the throttle body. the manual will tell you much better than I. thermowax / cold start / something like that.

 

yea i actually have the manual printed and in a binder, its really useful.
ill search more. any word on removing the cold start assist bottle and anything else that goes with it?

when setting the tps am i supposed to jumper anything?

my secondary throttle plates (the 2 connected to the diaphragm on front of the throttle body) dont work. they move, and if i move the plunger on the diaphragm by hand, they move, but putting vacuum on the line to the diaphragm causes no movement, i think its got a leak in it. can i take it off? i dont want to do the whole TB mod, but can i remove just the plates and the diaphragm? what about the thing that the hose to the diaphragm comes off of (on the back of the tb) i believe its the thermowax... can i rip that and still be ok?

 

yea more questions... please feel free to answer anything from previous posts too (PLEASE) i dont want to clutter up the forum with too many q's...

starting idle: ok and steady.
once the temp gauge touches the bottom of the 'C' ... it starts bouncing ~200 rpms. once it warms to about 1/3 the way up, it stops bouncing and is steady at whatever crappy idle it wants. why??!? i set and reset and set the tps SO many times now i can do it in my sleep. and yes i set it when hot.

also, my idle could be fine, but turning the lights on makes it (sometimes) almost stall and drop to about 600 (normal for me is 1k) and sometimes turning the lights on doesnt do anything to the idle.

anyone got a working BACV they want to send me?

 

Please indicate how you resolved your bad idle problem. Thanks

 

lol







set my timing properly.
how sad, eh

 

haha nice... thats how i finally got mine too... TPS, Idle screw on the TB, and the timing...

 

so, figure out what the throttle stop should be adjusted at? Mine was missing its screw so I do not know what position the throttle stop should be at. Any ideas or help?