MM120

After sitting overnight, my car doesn't want to stabilize its idle & will die, unless I give it some gas as soon as it turns over. After a minute or two, everything is fine. It'll start right up w/o any extra gas for the rest of the day, but the next day the process starts all over again at first start up. I just cleaned my ICV but don't have a working tester to check out its resistance. The cleaning didn't help though. Could it be O2 sensor or coolant temp sensor? Which would you lean more hevily towards? TIA!!!

PS. What oil should I use for my muffler bearings? ;-p

moribundman

I'm leaning towards coolant temp sensor.

Ghostfire

Not the coolant temp sensor. I had a bad one for ever the car never had a problem with shutting off at start up. How old are your o2's.

Personally I am thinking maybe its your regulator. Its not pumping enough juice possibly but once you start the car it gets the juices flowing like a horny chick and works fine. Until it sits and cant produce the juice again. I can be wrong. there are a few types of ways to check it.

My favorite is this tool I have I put it in the cig lighter location and it gives me a reading on my battery, alternator and regulator. Good luck!

Edit, with all that said the coolant temp sensor is like $10 or less and if you dont have huge hands takes five minuts to change. So I would change that if I suspected it at all first.

VIPSA

can measure the FPR which is mechanical from the cig lighter? I have that same tool but only reads the battery and the alternator.

Ghostfire

FPR=fuel presure regulator? No I mean the regulator in the alternator.

dorsal900

The oxygen sensor is ignored by the ECU for the first few minutes of engine operation until it heats up - that's why it has a heater. Coolant temp sensor (CTS) is easily checked out with a cheap Ohmmeter; do yourself a favor and get one at Home Depot or Radio Shack for about $10-15, you will find lots of uses for it. On startup, resistance value of the CTS should be fairly constant for the first few minutes, the ECU just needs a ballpark value.

The fact that the car idles fine after a few minutes leads me to believe that the ICV is OK - I just changed mine because the car would die once the engine was warmed up, cleaning didn't help, a new one cured the problem.

So, what would I be looking for? I'm not sure, but does the A4 have a valve in the fuel line to keep it pressurized (my other car does)? Perhaps the fuel needs some time to get back up to proper pressure? I have also found that different brands of gasoline produce suprisingly different starting results: BP/Amoco (one of the "best" brands here) produces poor starting, while Citgo (which some consider "poor") produces good starting results for me. Then of course there are the ever-popular possible vacuum leaks, which might affect a cold engine more severely, leaning out the mixture when it needs to be rich.

Mr.D-'97 A4q 12v

Has it been cold in the mornings this has happened? I notice mine acts up more when it's colder out and as the day warms it doesn't die (but the idle still dips).

The ICV can have the correct resistance and still have something mechanically wrong.

P.S. When you hit the accelerator pedal you are not really giving it "gas", you are giving it air. ;-)

moribundman

I thought he did.

Mr.D-'97 A4q 12v

Dunno, maybe.

MM120

I clean it periodically, but haven't changed it.