My idle when the car is warmed up is pretty much always about 600 rpm. Is theres something wrong? Or is that relatively normal?

Sometimes when ive driven any sort of distance to the point that the car is warmed up and turn it off, when i try to start it again itll turn over just fine, fire up alright to about 600 rpm, then just die out unless i keep my foot planted on the throttle (should i not do that?). If the car does start up fine often times the idle will rhythmically bounce up and down and dip so low that the car will stall. Usually from something like 500-900 give or take.

Vacuum leak? Adjustments needed?

 

Car runs perfectly fine aside from low idle by the way. Everything else is ok.

 

First things first. Ground (or short) the initial set connector. Adjust your TPS to 1 volt, engine fully warm or one test lamp lit, or 1000 Ohms, whichever method you use. Then adjust the idle to 750. Don't forget to remove the short/ground wire from the initial set connector. Now, take the car out for a test drive to see if your problem is still there. If so, then start looking for vacuum leaks.

 

Has the BAC been removed?

 

If it is an S5, back the idle air screw on the throttle body a full turn out while the car is not running. Trust me on this and report back.

 

Nope

 

That is the one on top of the tb with a black rubber piece covering it?

 

Yupper

 

Alright that made the running warm idle absolutely perfect after about a full turn and a half actually. But when i warm the car up, turn it off, leave it off for a bit, and start it again the idle is still real low until i drive it a bit. Then its perfect again.
Your tip did help though so thank you regardless

 

Wasn't my tip, but thanks anyways

When its low idle when you start it hot, does the exhaust smell rich? I wonder if you have a leaky injector. Also, lowish compression could give you the symptoms also

 

My compression is very good. Great actually.
Ill check when i leave the house again later

 

Could be a bad Pressure sensor, my s4 does something similar and pulling flashcodes led me in that direction

 

yeah it does smell rich on warm start. like i said compression is exceptional

 

If yoi haven't had your injectors serviced in awhile i'd start with that. Get them nice and clean and rebuilt and a new fuel filter and it may fix your hot start issue.

Only problem is it usually sets you back a week or so

 

I think i had it done when i got the car about a year and a half ago

 

if it was only a year or so ago, you SHOULD be ok, but doesn't mean anything. You best bet to find out for SURE is a fuel pressure tester, and hook it up and watch the PSI. If it drops quickly, than you know something is leaking