I have a 92 rs 305 tbi,

When I start the car after it has sat all nite, it just idles up & down religiously,
it idles from 1000 rpm down to about 100 rpm & back & fourth for about 5 minutes, then it drives fine.

After it warms up I can turn it off & on & it idles fine.

I've been thinking it may be the map sensor, because when I unplug the map sensor before starting it from cold, it idles just fine 8 out of 10 times, & it will run fine with map sensor unplugged, but it will die at stop lites if u dont hold the gas.

I have replaced the tps & iac.

Do u guys think the map sensor or the coolant temp sensor may be bad?

 

The coolant temperature sensor could do this. But like the other thread says, it'll make you run rich if anything. I am running a bad temperature sensor right now and I idle just fine, yet my fans won't turn on because the computer thinks that i'm still cold even though the guage (which works fine) is running into the red when you don't pay attention. Yet in my case, if i have my climate control in A/C the SES light won't trip, but if i have the climate control in any other function or off, then it will trip in less than five minutes. Thats how i figured out what was wrong and what i needed.

Then again for give or take less than $12 it woudln't hurt to try, there has been cases that this was the issue, but i'm just speaking from my situation, mine may run a bit rich, but it isn't having any issues idling. I am in the process of replacing mine, but i seriously need a coolant fluid change, and i'm waiting for a free moment.

Good luck!

 

Are you getting the SES light? Check all of your vacuum lines and wires.

 

ok, if i start the car with the climate control in any of the 3 A/C functions...the fan comes on automatically (apparenlty sum sort of safety thing, i'm assuming the larger load of heat operating the system) so the SES light doesn't come on...but if i have the climate control is in vent, bi, defog, defrost or off...and the fan doesn't come on, then i get an SES light in less than 5 minutes...it purely has to do with the heat i'm assuming, like i said, i gotta change out the sensor, i don't wanna ruin a new one, by not changing to new fluid first... (wires and vacuum lines all seem fine)

besides, right now i'm trying to figure out which fusible link at my starter decided to go on me because when i went to move the fuse block to wire in power windows/locks/mirrors/roof console...there was a huge spark...and now all i get is 1.095 in all my ign power points...i have no warning buzzer, no power to the ignition, no power to the flip up headlights, no brake lights, no turn signals, ect...all i got is a dome light basically...i tested the stud on the starter solenoid and i got batt voltage...but out of the 3 fusible links at the starter, i can't get batt voltage at one of em before or after, and this one is the wierd one...instead of all the others (one input from starter stud, one out to whereever), this one has one input from starter stud and 2 outputs...i've been looking at the '86 wiring diagrams from the tech page off the home page and wondering if that was fusible link A and B combined, but i don't even know how to replace em and if u can use a blade fuse in a water-proof rubber casing to make it easier to replace afterwards...