So I replaced my rear brake pads today without a hitch, it was an easy and fun afternoon with the car. Forgot the restrictor pill (damnit) but I'll jack with that monday.

I noticed that there was only one spring on the calipers to pull the pads away from the rotor. Is it supposed to be like that, because it seems like there needs to be 2 springs per caliper.

Now to the hot idle issue. Today, it got into the 90's, and I noticed that the car would idle rather low. It was within the 500ish rpm range. This was when the car was fully warmed up and it being so hot outside. Cold, Warm, no issues. It actually tends to idle slightly high when it is cold.

Last year, I adjusted the idle screw to fix the low idle and had to adjust the screw again when it got cold outside again to get it back down. Something tells me that on a semi-modern fuel injected car, I shouldn't have to do this?

 

Forgot to note, this is a new engine with roughly 9k miles on it. OEM ECU, no idle mods at all, all stock S5 car. Has a good TPS which was replaced at the same time as the engine.

 

Does it die when it idles low? Things that can affect idle other than the adjustment screw...

-TPS. make sure it is set at 1 volt warmed up.
-Timing. Get the marks right on the timing pin when warm.
-Aux ports stuck in the open position.

If it doesn't stall, then you can rule out vacuum leaks. Have you checked for codes? Lightweight flywheel?

 

VERY strong compression motor, just to rule that one out.

-Does not stall. One leading plug died on me and the thing would still idle at 250rpm without stalling.

-TPS adjusted per FSM

-Timing is slightly advanced (don't remember exactly, but it's very little). Chriss Ott ar RP did it.

-Aux ports aren't stuck open.

-Stock flywheel and I have no codes.


My idle is usually between 800-900rpm on any given day until outside temperatures get 90+.

 

I know i shouldn't have to do this twice a year due to seasons (we only have 2) but I guess I'll just adjust the damn idle screw again to get it where it needs to be and report back.

 

Sometimes a faulty o2, intake air temp, or coolant temp sensor will not throw a code. Just replace each one. They are cheap and should be replaced anyway if they are nearly original.

Also... How are the BAC and ACV? Does it idle low with AC on?

Maybe try a switch check.Being in and out of certain switches will change your fuel mixture. Ground the code check plug and move everything around like your driving the car and see if the CEL corresponds. (clutch, shifter, headlights, AC,blower, defroster etc. Could be a bad switch or ECU.

 

narrow band shows the ACV is switching port air on and off as it should. No backfires other than your normal high rpm popping during shift. Don't have an AC, but when I flick the headlights on, the BAC does respond.

I'll try your suggestion and post back up.

 

i dont know if you fixed your issue with the idle, but when my idle is off and my tps and everything else checks out, I adjust the variable resistor and that usually smooths my idle right out.

 

when i get a new FC i have to adjust the TPS/idle when i get it, and then about 6 months later when the weather changes, about the 3rd time i check it, and its fine

 

Don't have the variable resistor on an S5. I did however fix the problem by adjusting the thermowax slightly. I replaced it when I rebuilt the engine and it idled fine then, but it needed some fine tuning this season.