I dont know if you ever crossed my thread about my frustration on this exact same problem,, but I solved mine, unfortunately it was my opti, water pump, plugs and wires. My opti was rusted and it was crazy and my water pump got all kinds of signs of leaking. My plugs were gapped differently ranging from 40 - 80. It's crazy.

It was exact the same as yours. Now I have a freaking vibration problem...

This car never stops complaining!

 

Mine 97 z is doing the same thing. My car symptoms are: When i crank the car, instead of the "high Idle" the car just goes straight to 800 and just lops. I have cc305, heads, headers, all the usual stuff. When my car doesnt skip until the temperture gauge goes the the 1/4 mark, not sure what the exact temp is. I have a new opti and tomorrow i am changing the Map sensor, and cleaning the IAT and throttle body. I have new plugs and wires, my only real idea is that maybe when everything gets hot, maybe the spark in the wires are breaking down, heck i really dont have and idea.

Thanks people, lets find a cure
S.C. Smith

 

i got this problem too so. I have no clue. Just wanted to subscribe to email notice for the thread.

 

licerio, the one thing that holds me back from changing the opti is that on my scanner once my car goes into closed loop it has a slightly rougher idle. I am thinking o2s or a vacuum leak.

But then since it only does it on hot days or running for more than 30 mins or so i want to think heatsoaked coil or opti.

I think the dealer is gonna be in my future this summer i dont have time to fudge around.

 

I have the same car as you a 94 A4..

Anyways, check your water pump for any signs of leak,, like the weaphole...mine was very visible and can see dark spots and green spots for the coolant. I'm no expert but this was all my symptoms...it drives fine until driving until 30 minutes or so city driving, even drive fine sometimes on the highway,, its crazy. plus I changed everything at once...

plugs
wires
opti
water pump

my opti was rusted...and my plugs were gapped differently accross. If you see any signs of water pump leak, I can almost assure that its your opti...sorry

 

If you suspect something is getting hot, why don't you cool it with freeze spray available at a local electronics shop? This works very well as many electrical failures are heat related.

Conversely, if the car is cool from having sat for quite a while, you can artificially heat up items with a hair dryer and see if they are crappy when warm then cool them down and see if the good condition returns.

Second, if your running crappy at anytime, either have the plug wires put on an O-Scope to see the condition of the spark graphically. Or monitor the O2's to see if the engine is richening up.

Third, you could monitor the IAC counts to see if the engine is causing the surging by changing the postion of the IAC.

Hope this helps