My buddy and I installed a GM 847 cam and a set of P&P heads(Advanced Induction) on a 97 z28 A4. It keeps coming up with a #3 cylinder misfire, and it is sporadic. We changed the plug, wire, and injector and it still gives the misfire code. We are completely stumped.

Any suggestions?

Here are his mods:
PCM4less programming
LT4 KM
GM 847 cam
P&P heads
Jet-hot LT headers
Electric h20 pump
Underdrive pulley
52mm TB
stock injectors
new O2 sensors
SLP cai
Thunder racing MAF ends
taylor wires
Autolite 104 plugs

 

I wouldn't believe any computer sending a code especially one that's been reprogrammed. Confirm (or rule out) the misfire by having the plug wires checked on an O-scope. Also open the hood at night and see if there is a light show.

One last thing you can do yourself. Put salt and water in a spray bottle and lightly mist the distributor from underneath. It helps to put the car up on ramps when you do. Don't drowned the thing, just lightly mist it. Now look for sparks while it's running. At night helps.

You may find out you need a distributor. Do some checking first though, don't just jump into the distributor.

 

It did it when we changed wires. I failed to mention that the opti was new as well.

 

Anyone?

 

#3 misfire!!! anyone?