2G IAC topic? Idle Surging

[super97gst]

i pulled the plug off my iac tonight and checked the iac. all was good on an ohm test. i then pulled the electical part of the iac out of the throttle body. just to make sure all was clean. when i put everything back together i had hecka idle surge. biss all the way in makes little difference. should the ecu have to reset itself after pulling the electical part of the iac out?? every time i pull the battery off my gst i have to drive the car for a couple hours to get the ecu to reset. but i dont get idle surge then, i get real low idle. after a while though it always straightens itself out. just curious about this.

BTW, i have not been having ne of these idle surge problems before i pulled the iac off. just wanting to know if this is normal and if the ecu will reset it. thanks

 

[steve]

Did you replace the o-ring that seals the ISC/IAC?

 

[super97gst]

i didnt go that far in. i only unplugged the iac, then pulled the 3 screws out and took out the electircal part of the iac off, the part that has the 4 coils in it. i didnt pull the plunger out, i just pushed it in and out a couple times to make sure it wasnt stuck or dirty. when i pulled the car into the shop it was running fine. when i cranked it back up i had idle surge.

edit: unless you are talking about the orange seal between the electrical part and the housing the plunger sits in. but i made sure that it was seated correctly when i reinstalled it, as per instructions in the repair manual.

 

[steve]

You don't usually take the ISC apart to measure the coil resistance.
You either pull it or measure them on the car.

Are you sure it went back together correctly with the spring on the bearing. Since you moved the pintle if the ISC isn't operating correctly you could have induced the surge by allowing more air to bypass the ISC.

The ECU will attempt to relearn the ISC positioning. It will do so right away after an ECU reset and once it decides it needs to if the ECU isn't reset.

If you adjusted the BISS as well you will need to verify that the ISC is working, bring the car up to operating temps and readjust the BISS per the FSM.

 

[super97gst]

ok. thanks steve. i believe thats what it is. i havent drove it yesterday and it idled just fine when i cranked it. after i drove it for about an hour it went back to surging. i think i just need to readjust the biss and let the ecu reset itself. i appreciate the help.

 

[super97gst]

i thought this problem had been getting a little better. most of the surging had stopped and it was just idling at around 1800 constant. i was running down the highway today and it lost everything. no power whatsoever, this is why i thought the iac was bad in the first place. but it checked out fine. neways, now the car idles lower than the tach will go. the engine shakes so bad it looks like its fixing to fall off the mounts. it will only boost to 5psi. and it has no power, i mean its bogging so bad it wont even run at all.

am i still looking at a possible bad iac motor?? the car was doing this exact thing when all of this started, but i went out to test the iac and it ran fine. then the surging, now this.
what do i do guys??