High idle, lots of diagnosis!

[5Toes]

Okay so my car idles high, its annoying!

Here is what I have done:
New intake boot
New intake manifold gaskets
New bitch tube gaskets
New valve cover gasket
All new vac lines
M50 injectors with rebuild kits
New oxygen sensor

Otherwise bone stock car...

Now with the oxygen sensor unplugged it idles right at 750! Except it wurrs back and forth ever so slightly. So I know a 750 idle is possible!

I just tested my coolant temp sensor. In 180 degree water it is reading 300 ohms.. so spot on!

I am thinking with this new o2 sensor I need to reset the ecu.. Ill try that later this week.

Any ideas guys? I am fairly certain I dont have a major vacleak

[5Toes]

Also, forgot to add that I have a new TPS as well. When i unplug my TPS idle shoots to 2000 something so ICV is working

[camip]

Get a horse just add hay and water and no problems. Willing to trade my three horses for your one e30.

pm me

[jlevie]

You have replaced only about half of the stuff that can result in an intake leak. Have a smoke test run to see if there are any leaks. After eliminating any leaks you may need to adjust the throttle, but first look to see if someone has twiddled the bypass air adjustment in the AFM. It should be still sealed.

[5Toes]

And how does one do that?

EDIT: found out, I am pretty sure it has never been messed with.. the AFM

[jlevie]

If you are asking how to do a smoke test, the procedure is:

1) plug the exhaust
2) replace the AFM with an adapter for smoke injection
3) connect the smoke machine and feed in smoke until a pressure of 2-4psi is achieved
4) hold that smoke pressure for at least five minutes so smoke can reach any leak

[5Toes]

Say I have no vac leaks.. what else could be the problem?

[jlevie]

Once I had proof that there were no intakes by passing a smoke test and a vacuum test of the brake booster I'd consider other possibilities, but only then. Possible causes after intake leaks have been ruled out include:

1) A bad or sticking ICV
2) A sticking AFM vane
3) Misadjusted idle air bypass adjustment in the AFM
4) A sticking throttle plate or misadjusted throttle
5) A bad evap control valve
6) Power on the idle speed increase pin of the DME when A/C is off
7) A fault in the DME

[5Toes]

Well come to think of it i did make my own injector wiring harness. I need to test for continuity for the CTS... easy enough I am imagining.

ICV isnt sticking
AFM vane I believe is okay, will make sure though
throttle is fine.
evap control valve.. meh maybe
I see if the ac button does anything (AC is deleted)

Like I said I will reset DME and go form there

[jlevie]

Well come to think of it i did make my own injector wiring harness. I need to test for continuity for the CTS... easy enough I am imagining.

ICV isnt sticking

How would you know? You can't tell what the position of the vane is with the ICV connected to the engine.

AFM vane I believe is okay, will make sure though

That you can sort of check if you peel the plastic cover off.

throttle is fine.

How would you know if the throttle stop has been changed from the initial factory setting?

evap control valve.. meh maybe
I see if the ac button does anything (AC is deleted)

Like I said I will reset DME and go form there

[5Toes]

Ill read up on throttle stop screw. However what I meant is that the cable is adjusted right..

I thought icvs either work or they don't?

[Stabmasterflex]

I have same issue. I idle at 1000. I'm going to try that evap valve. I did have a bad throttle body gasket that I changed. Thought I had er beat. Nope.

[5Toes]

Oh yes, my throttle pbody gasket is newer too

Ill try plugging that hole on the throttle with my finger and see..

[5Toes]

So as I said my AC is deleted.. but when pressing the ac switch and having it light up no change in idle is noticed

[jlevie]

That may mean that the A/C switch is bad, the slider switch is bad, or the A/C on signal isn't reaching the DME.