Pulsating Idle

[stormbringer]

Hi. I have these pulsating idle problem. my RPM goes up, down,up,down. I first noticed this on while on stop with the AC on. I tried turning off the AC and it still pulsating.And when I drove without AC the idle seems ok, and then I stopped again, it starts to pulsate again. I cleaned the throttle body thoroughly coz i thought this is whats causing it. I started it, at first the idle is ok then when i run the car and when i stop the pulsating starts again. I remember the day before it acts like this, while inspecting under the hood, I noticed a disconnected plug or a prong(or whatever you might call it) and I connected it thinking it was accidentally disconnected and it fits anyway no doubt about it. this plug is located on the firewall (wiper side).what is this plug? eversince I connected this, the idle becomes pulsating. when I unplugged it, the idle rises up without pulsation! when plugged, the idle goes down with pulsations! i have to adjust it up just to make it stable! please anyone help please. I dont know what to check next. thanks

[stormbringer]

I forgot, My ride is a 1994 galant

[nyjets985]

spark plugs ??? how old r they mine 99' G did the pulsating idle and it was the plugs

[stormbringer]

thanks for the reply. I was thinking of the sparkplugs too. my sparkplugs are almost 4 months old. But what confuses me is that the idle runs ok when this 3 prong triangular (switch?plug?connector?) thing attached to the firewall on the wiperside is disconnected. I dont know if this is connected to a sensor.if this is disconnected its normal idle. but when i connect it, idle screw up. I want everything in the car to be standard thats why i want this thing connected. Im also afraid it might cause or create any other trouble unknown to me if this is disconnected. I will change the sparkplugs for now and I will post whatever the outcome is.

[cougar214]

can you tell me the year and model of your car and i can look it up for you and try and figure out what this plug is.

[bronxbombr]

take a pic of the thing.

[JAG1128]

i have the same prob as with your 7g.There were even times when the idle just goes wild over 3K RPM.I think its the serbo. Here in the philippines, theyre selling a surplus for 3.5k pesos, its kinda cheap.But no guarantee on how long it will last.

[drei.rpglnt]

check the servo. the servo has everything to do with idle. mine got broken several times -the servo's magnet and gears. not sure though what plug u r referring to.

[Skitt2112]

Mine does the same thing sometimes. Only at a stop and it'll drop rpm's every once in a while. Died once or twice because of it. Mine doesn't spike up though only drops and then goes back to normal.

[mko]

https://www.thegalantcenter.org/showthread.php?t=42787

[bronxbombr]

looks like IAC motor is going bad.

[peanotation]

sounds like the god awful IAC/FIAV is going bad, which is it's job, to go bad

[master_visionary]

I have this problem which is perfect now I can slip a 60mm TB under the ever inquiring eyes of ...dunh dunh ..the wife this is lovely
She is always suspecting me of tryna make my cars faster

Well I never ;-)