Hello all. I've searched missfire posts and I've learned alot but I'm trying to fix my problem without throwing parts at it. Car is a '96 Z28 A4 w/67,000 miles. I scanned it before doing anything and came up with: PO141-O2 heater circuit bank 1 sensor 2 and PO300-random cylinder missfire. Cylinders 1,4,and 8 showed very high missfire counts(1000- 2000)after previously clearing codes(about 400 miles). I replaced the plugs with factory delco platinums gapped .050. I also installed Taylor 8mm Spiro-pros. I was carefull with the routing as well. It seemed to run better but I still got missfires @ same RPM's(1100-2200) under light loads after car warmed up. I scanned it again and cyl. 1,4,and 8 showed missfires counts in the 600-700 range after driving about 430 miles since the last code clear. I checked the resistance on the wires with the high missfire counts and they were all around the same as the others. I'm looking for any suggestions before I go and replace the optispark and ignition coil. I'm kind of leaning away from the coil because of the consistent miss counts in the same cylinders before and after the plug and wire change. Thanks in advance.

 

Gap your plugs on .035 and try it.

Let me know if it works.

 

ttt..any suggestions please

 

Turns out it was the EGR valve....just thought this may help others with the same problem.

 

if you dont mind me asking how much was the EGR valve new and what is the part # for it. I have a very similer prob.
Thanks!

 

I didn't buy it yet. I just disconnected it and car runs 100% better....no missfires at all. Try disconnecting yours and see what happens. Good luck.