Idle bouncing from 1200-1500

[Spoolin4Ever]

Problem is my idle constantly goes up and down from about 1200-1500 (when warm(, when cold it also bounces up and down as it gradually reduces from 2500 down to 1500. In other words when cold it bounces from like 2500-2200, and gradually goes down to settle at bouncing from 1200-1500.

It all started when I was working on switching out my starter. I was doing that at night and I was getting frustrated. What happened is that I bonked the starter into a few things pulling it out and putting it in. I hit the ISC and the IPS, and I think I may have "bonked" the FIAV. Oh yeah, and when it hit the ISC, it actually hit the wire going to the ISC (harness).

Ever since I started it that day, I was having idle problems. Well the ISC had a bad coil, I replaced it. I also replaced the IPS, and I have tested the TPS it is good.

By the way, when I turn the Biss the idle stays the same no matter what. If I unplug the ISC< it still behaves the exact same way.

I'm trying to determine if it is the ISC wire or the FIAV.

If it is the wire, I have one from a car in the junkyard, I'd like to make a new harness setup. Where does that ISC plug into the ECU or what?

Any quick easy way to troubleshoot this?

Known good parts:
ISC
TPS
IPS
Biss

PS Even when not at idle, it will still try and maintain those RPM if I let them go down. Also when taking foot off gas it takes a while for idle to drop.

 

[Lofty]

First off, are you properly jumping the BISS switch?
If you turn it without gator clipping that switch, the ISC will just fight the adjustment.

 

[Spoolin4Ever]

First off, are you properly jumping the BISS switch?
If you turn it without gator clipping that switch, the ISC will just fight the adjustment.

Yes I did, thanks for the response.

Essentially the car acts as if there is no ISC. So in other words it acts the same whether it is plugged in or not. The BISS screw does not seem to effect it either way (much).

I still am looking into the wiring harness that goes to the ISC.

What can make the car act like there is no ISC, in other words idles and drives exactly the same whether it is plugged in or not?

Can FIAV or EGR ever do that?

 

[Lofty]

Not sure about the EGR and FIAV.
But I can pm you a Wiring Diag if you want so you can see exactly where it runs to.
Do you have any exhaust leaks??

 

[Spoolin4Ever]

RESOLVED: it was the FIAV.

I ended up swapping out a throttle body that I put the FIAV AND ISC blockoff.

I was getting pretty fed up trying to troubleshoot this, plus I drove around with a car that would always rev from 1000-1500 whenever at idle, whether moving or not Extremely annoying and frustrating. I drove it like that for about 3 months was actually almost used to it but I felt sorry for all the other pepople at the lights hehe.

Yeah when I swapped out the throttle bodies I saw green coolant in my intake manifold THat's how I know it was the FIAV I acciedentally smacked it with the starter when I was taking it out becuase my alternator was bad (frickin StarMart sucks no wonder they went out of biz)..

 

[datrip]

Issue still fixed? Ever figure out what it really was?

 

[Spoolin4Ever]

Issue still fixed? Ever figure out what it really was?

Like I said: FIAV was bad.

 

[eLaNG]

I seem to have the same problem as you. Is there anyway to change the FIAV without a swapping the entire throttle body? thanks