tholm1

I am absolutely stumped. My 95 A4 LT1 runs like a champ for the first 5-10 minutes after start-up. Once I get to about 195 deg F, the car simply will not idle smoothly, eventually stalls out particularly when I give it throttle leaving an intersection. Anything about 1100 rpm I'm running fine. WOT is pefect.

Here what I do know.

Injectors Ohmed out ok
Fuel Pressure is steady at 38 psi at idle
ICM, Coil, Coil Lead Wire, EGR replaced
New IAC (proper intial adjustment done)
TP sensor voltages are good.
I temporarly blocked of the EVAP vacuum line on the throttle body, no change.
I also deep cleaned the throttle body.

No codes.

Looking at datamaster my long term counts creep up to 160, which tells me I'm running lean.

The O2 readings are not steady. The swing between 100 and 800 wildly. Is this normal? If not then maybe my O2s are bad?

This problem started when I took the water pump and opti-spark off to replace the timing cover oil seals and install a speed-sleeve.

Does anyone have any ideas? Do any of these symptoms sound familiar?

tholm1

Does anyone have any experience using datamaster to know what a normal O2 voltage should be and if I should be getting a stable reading or should it oscilate between 150 and 800 mV rapidly?

SAY WHEN

From your symptoms--and what you've already checked/replaced-- I'd suspect the Mass Air Flow Sensor--you should be able to monitor it with a scan tool--once the engine is warmed up(closed loop) it should read approx.---6gm/sec to 9gm/sec at IDLE---the #s should increase rapidly when you accellerate--could be dirty internally OR gone bad period. I'm guessing you have no codes--they will set codes but not always.