surging idle and how to fix

zeusmoto

New Member
Feb 15, 2004
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utah
k guys my engine idles at about 700 rpm. sometimes it will surge to 900 then drop again. why what specifically should i look for and how should i fix it i heard something about iac but due to my newbness and ignorance i dont even know what it looks like.. please someone help i want to jump my idle up to 1000 or even 900 and definetly stop the surges... well guys help asap would be nice...


zeus
 
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Ok....
To set your idle, first make sure the car is at operating temperatures, warmed up.
Get the car idling then unplug the IAC, which the long cylinder on the front side of the throttle body. Then turn the idle set screw until the idle is near where you want it to be. The idle set screw is down on the backside of the TB.
Now you will need a multimeter to complete this. In fact, make sure you have one before you start.
And with this meter, measure the voltage across the green and black wires of the TPS, the sensor on top of the throttle body. Use the black wire as a grounds reference.
Now with it idling still, turn the car off, plug the IAC back in and unplug the battery so the computer resets, and car can learn the new idle.

That should be it!
 
k well with the multi meter what should it be set at? before i turn it off... also what else would cause a surgelike that,.. besides a vacuum leak.. alsohow would i track down a vacuum leak and how would i fix it?
 
dont forget that the puter will try to get the idle back down to the stock setting, which can lead to it fighting itself (compensating in other ways).

the IAC is the cylinder on the front of the TB, as Prox said. you can pull it off and clean the pintle. there are also bypass plates (~15 bucks) that allow more air to pass. it works for some guys.

with the blower, if you had a vac leak, you should be able to hear it. do you have a boost/vac gauge? if not, you probably should (i did on my turbo'd car - nice to know what you got).

if setting the TPS, i would use the DCV setting - at the lowest setting over 5 volts (generally 10).

good luck, Zeus.
 
zeusmoto said:
k guys my engine idles at about 700 rpm. sometimes it will surge to 900 then drop again. why what specifically should i look for and how should i fix it i heard something about iac but due to my newbness and ignorance i dont even know what it looks like.. please someone help i want to jump my idle up to 1000 or even 900 and definetly stop the surges... well guys help asap would be nice...
zeus

Been here and still have this happen. With my car (I call her bitch for good reason, I should name her Carrie I swear to god), I run better rich in the summer and I have to adjust the timming in the colder months everytime. If I don't my car will sit an search for an idle spot. I know it should adjust automaticly, but it doesn't. A previous owner has done some amazing things that I dont know about, and it keeps my car stronger then she should be. When I adjust it I unplug the chip, adjust the timming and then plug it back in. And it works every time.
 
The idle adjustment screw is closed to far. Turning this will open the throttle, and help the car idle. The car should be able to idle without the IAC.
So, just turn that screw on the back lower side of the throttle body. This is the same screw you use to set your idle where you want it to be.