Stupid Idle Surge

[Halon]

ok well ever since the day i bought this car, it had a very little idle surge going on. Well it's gotten worse and worse. First thing I thought was maybe its the EGR, so I went ahead and did the emissions removal thing according to Taboo's site. Well it was still there, so then I tested my ISC, i got an open reading on 1 of the 4 coils. I then purchased another ISC. Put that in. Problem is still there. Then I found out my EGR blockoff plate was leaking. Thought maybe that could cause it to do it. So today i went and sealed it up real good. Idle surge is still there. Anyone have any pointers they could throw at me to get rid of this. I take the near 2000 mile road trip to MN end of May, and I'd like it to be gone for the trip. Thanx!

[A//// Guy]

Your fast idle valve is likely the problem. You will either need a new bottom half of a throttle body (FIAV) or a whole new one... whichever you find for the cheapest I guess.

That was the problem with mine.

[Jacek]

check the biss screw o-ring while at it.

[unreal808]

-Operates as Designed-
:goodluck:

5 ways air passes TB: throttle plate, base idle speed screw (biss), ISC, FIAV and egr. ECU moves ISC around all the time when driving. When let off throttle, ECU steps the ISC all the way open to "catch" the engine as the RPM's fall below 1000. Now we know this. First thing to do is set the ISC. Should be done before every season or once a year, especially after modifications or when more air flow. Do this when engine is hot. I cannot stress this enough or on a hot day as well. I don't know what year your vehicle is, but you will need to ground ignition timing adjustment with jumper wire. Then the engine will run steady and ECU can't fiddle with ISC. I have 95' eclipse and its the brown connector on fire wall. Now just adjust biss until steady run at 750 or if you have big turbo HP, maybe set at 750-1000. If you have DSM link match both. Now you will have tuned ISC and disconnect ground. Now you set the correct range for ISC. You may have to replace rubber o-ring for biss. If this does not work. Then you eliminated base idle failure along with the fact you checked EGR and replaced ISC. So then it is FIAV which you will have to replace or clean the throttle body. If none of this works the car is not running correct or vacuum leak, or even bad o2 sensor which you can check by smelling exhaust when car surging. check terry's talon troubleshooting tips under idle surge in vfact on dsm talk. I must mention most of the time its just adjustment of biss when you ground ignition timing. Allot of information, sorry about that. Hope you fix.

[LightningGSX]

The transistors(inside the ECU) that control the ISC have a habit of frying also.Open your ECU and check IC107 and IC105(Black with 8 pins, up by the connector, off to the side) for damage.

[Halon]

cool thanx. i have pretty much all day tomorrow to screw with this so ill be trying to do these adjustments. I'm not sure where this ignition timing thing is that im supposed to ground out, but ill look around to try and figure it out. thanx for the replies.

I should stress, you will have to ground the ignition timing adjustment to fix. Cannot just adjust biss. Pick up Chiltons book at checker or different store for your car. Your vehicle may have to be grounded different position. I hope goes well.

[Halon]

i have a chiltons for the car already. I went on vfaq and grounded the ignition timing per the vfaq. Once the 2 points were grounded, guess what. IDLE SURGE IS STILL F*$%ING THERE! This is really starting to drive me nuts. I also did what it said about checking the vacuum lines real quick. I don't have that many lines because I did Taboo's lil emissions removal. But I took off every vacuum line and put my finger over the ends, and nothing had any sort of impact. I am about to take off the TB Elbow and clean the sh!t outta the throttle body. Then if that doesn't help, the I dunno, maybe I'll just go and do that FIAV removal they have on vfaq. Also, I don't really know how to check the o-ring on the BISS. I tried just putting my finger over the top of the hole and sealing it with my finger, so i know no air could escape. But that didn't do anything. Anyway, I'm off to go clean the TB. Please keep the info coming, I'm really running outta patience with this.

[Halon]

Real quick, you said there is 5 ways air can get past the TB. Well here's what I've figured I've eliminated so far

-ISC (replaced about 30 miles ago)
-EGR (Blocked off and emissions removed as per TSS vfaq)

what's left is:

-BISS (not sure how to check this)
-FIAV (how do i check? can i just do the blockoff like vfaq and by doing this would that eliminate it as the being the culprit?)
-Throttle Plate (I'm going to clean it right now, anything else I can do to check this?)

[A//// Guy]

Like I already told you Im pretty sure its your FIAV. Try and find another TB and swap it out. Cleaning your original one would only help if the valves are really plugged. But that ussually doesnt cause surge.

[Halon]

What if I did this then?

http://www.vallotton.com/fiavblockoff.asp

By doing this, I would be basically taking the whole FIAV out of the system because I'd be blocking it off. So that would make me assume that if mine was really causing this problem, then doing this block of thing, it should get rid of the idle surge. Am I correct in assuming this? If so, then I think this is what I will be doing a lil later on. Thanx again everyone.

[A//// Guy]

I guess if you live in Arizona that mod is fine but when it gets cold I think that some people have problems starting the car. Is the idle surge constant or does it go away after the car is warmed up?

[Halon]

The problem is constant. Surge is there all day, every day. I think I'm going to try this block-off here shortly. It's not that cold here. I will be in MN in about a month. And if it starts causing problems, then I'll look into getting another throttle body. But for now I think ill do the block off, that way I atleast will know if this is what's causing the idle surge.

[Halon]

just pulled the TB off. By just looking at it, it seems that the throttle plate is not closing fully. Its like that little idle screw switch thing that the singe green wire plugs into is causing this. Like it's too tight or something. It being too tight is not letting the plate close all the way because its hitting the switch too soon so its not fully closing. Does that make sense at all? Anyway, the plate is a lil dirty too so I'm gunna go ahead and clean it, and then back out that idle position switch or whatever its called so the plate can close fully. I really do hope this is the end of my idle surge problems. I got my fingers crossed!

[Halon]

I just put everything back together. I haven't started the car up yet, but I will in a little bit. It's too damn hot out. I'm working in like 20 minute intervals right now. I think its only like 95 out, but i'm workin right under the sun, the blacktop is hot as hell, and all the engine parts are getting hot from the sun. Plus the fact that I'm scared to start it up cuz I just know the surge is gunna still be there cuz I'm not that lucky.

[Halon]

also one other quick question. the female connector in the engine bay with the pin you need to ground. Is this supposed to be plugged into something normally or does it just sit there unplugged always? Mine doesn't have the little cap on it that VFAQ talks about, its just a plug with one wire going into it taped to a bigger wire bundle.

[Halon]

ok, so i got the throttle plate set right. Installed it, grounded the engine bay and interior leads and started her up and got ready to adjust the BISS. Well I start her up, and of course like i dreaded, the damn thing started surging. Now I found out that if I unground the interior lead and leave the engine bay one hooked up, then i have no surge at all. But it idles around like 1200. Doing this I also think that my BISS is leaking. When I put my finger on the top, I can feel it sucking air. So I'm going to have to find a new oring for that i suppose. OK so if i have only the engine bay lead grounded, I have no surge. Now if i unhook it and leave neither of the leads grounded, it surges. If I have only the interior one grounded, it surges. If I have both grounded, it surges. But if I have only the engine bay one grounded, i get no surge. Does that maybe explain anything? I dunno, I'm gunna get a new o-ring for it someday. Also I'm gunna see if my buddy with a 92 awd laser will let me throw his TB on my car someday. It's freaking hot outside, I am done working on it until the sun starts setting. And I'm trying to find a sumone with a stupid digital camera so i can take pics of all my new powdercoated stuff.

[Kracka]

Originally posted by me612@Apr 23 2004, 01:22 PM
-BISS (not sure how to check this)
-FIAV (how do i check? can i just do the blockoff like vfaq and by doing this would that eliminate it as the being the culprit?)
-Throttle Plate (I'm going to clean it right now, anything else I can do to check this?)

BISS: put your thumb over the BISS screw hole and see if anything changes...or put a few drops of water on top of the screw to see if it bubbles at all.

FIAV: blocking it off will eliminate it

Sounds like your adjusting the biss correctly. The FIAV needs to be replaced with a new one. Where do you live. I am south of the cities. I can stop by tommorrow or sunday and help. Plus I can make a photo copy of notes I have off of old vfaq which is really good and explains everything so you have for reference. I wished it was just adjustment of biss for you, it will take a little longer for ya. Reason you have no surge when ignition grounded is because ECU does not have control of ISC, it cannot fiddle with. I am starting to think your valve is locked on FIAV.