Car idling between 800 & 2000 RPM ???

Hey everyone, ha, its me again with another problem.  This problem I've had for a little while and tried adjusting throught my DSM Link but it still seems to be speradic.  So here's the problem...  One day I may start my car and It will idle at 1000 rpm with no problem, and then all of a sudden it may rise to 1200 or 1500 rpm on its own.  It may stay at that idle or go back down to 1000 rpm after a minute or two.  Now on other occasions I may turn the car on and it idle at 2000 rpm, or I could be driving and come to a stop and with my foot on the clutch it could be idling around 1000-2000 rpm.  This is completley speradic, I talked with some friends and we all agreed it was most likely the idle sensor, but I thought I would throw it past you guys too just to make sure.  I know I need to just buy myself that damn Haynes Manual so I can look at what options I have and how and where to replace the parts if need be.  But anyway, let me know what you think, thanks.

I haven't really had a problem with the car idling around 800 rpm lately, but I believe that was due to the fact of my battery not holding a good charge. when I reved my engine and the rpm's dropped they would pass the 1000 mark and dip down to 800 and even 500 sometimes. Beleive it or not I haven't replaced the battery yet, because I need to run the replacement battery to the back of the car, the intercooler piping took up part of the room where the battery usually sits, so the battery thats there now is half the normal size of a car battery, but Its a small performance battery.  Personally I plan to put a red top optima in its place once I have the wires ran to the back, but like I said so far its been doing fine, but its on the "to do" list.  And yes I know I could damage my alternator the longer I wait, I plan to change the battery soon.

I just cam across this, http://www.vfaq.com/mods/BISS-2G.html

Do you think it could just be the BISS?

have you tried cleaning out your throttle body first. Just something to look into. How is your A/F ratio at idle?

no it shouldnt be the BISS because that will only raise and lower it manually. The only time that is the problem is if you have a constant high or low idle. Unless the biss is leaking air, but that would most likely just cuase alot of idle surging. Which yours is kinda sparatic

also it might be your ISC (idle speed control) motor

I dont have the Wideband hooked up right now, but I can look at it through DSM link, I'll do that at lunch today and let you know exaclty what it's running at.

Ok, here's a video of the idle issue, http://www.youtube.com/watch?v=5AbcbmHSTPo

could this possible be as simple as a vaccume leak?

or, i think these cars should idle around 900-1000 so does it do this when it is warm? if it only does it cold it is just kinda like a choke, it idles wierd when cold so it can warm up..

The car does this no matter what, at least thats what I've seen. I dont believe the outside teperature effects it that much, and if it does it's not enough to notice a difference.

ok.. and for the record the out side air has nothing to do with it engaging choke, thats just to warm up the engine... it can be 90 out and still do it... so how about the possibility of a vaccume leak? and does it run bad when driving or just idle bad?

Just idle.  The car runs perfect when normally driving it. 

Hey! a thought just hit me, remember my other post when I said the car stuttered above 5000rpm, and everyone suggested to replace the spark plugs and wires......well, do you think this could be a possible culprit to the idle problem too???

hey did you ever figure out what was causing the problem becouse my 98 420a is doing the same thing

Ok, I am in the process of working on the car this weekend, and so far we have upgraded the cams(272 Brian Crower), added ARP head studs, new headgasket replaced(Cometic), as well as the thermostat gasket, new valve cover(powdercoated), and new timing belt put on(HKS Kevlar Belt) which was a PAIN IN THE ASSSS!!! One problem I have now is that the car will turn over but not start, we finished all that work yesterday after about 10hrs, so when we tried to start it we said we will get some rest and pick it up in the morning. So as of now we are getting ready to look at the car again, if any one has any suggestions feel free to toss them my way and I will check this post periodically, I will also update this once we discover the problem. Thanks.

Make sure the timing marks are all ok, make sure all the sensors are plugged in.  Double check everything.

Ok, we know all timing is correct, but we just found there is no spark. No we are on the hunt to find the culprit, I will keep updates coming.