Having big problems on my 94 A4 Z28. started it up in the driveway couple days ago and had a bad miss and engine was shaking bad. felt like it was camming real hard but i have all stock internals, cam, heads, etc.

popped the valvecovers and springs are all fine, no metal anywhere, valves are adjusted fine.

took off the opti to inspect, nothing out of the ordinary, a little dirty though, but nothing that looked like the culprit.

checked all the plugs and except for the normal wear, nothing out of the ordinary either. i'm thinking this has to be a spark/fuel problem but wouldnt i be able to tell something from looking at the plugs? i'm stumped right now but waiting for a new cap and rotor for the opti since the car has 113,000 on it anyways and i'm going to do the OTVC wires at the same time. can anyone shed some light here or any helpful advice? i'm gonna go through the injectors if the opti tune up is a failure.

 

my favorite part is how you made taking off and checking all these things sound so simple...


SCAN IT!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Sounds like it's ignition related. Have you checked all your plug wires for burns? Also, what's been done to the car?

 

The best thing to do is use an infrared thermometer and check the temperature at each manifold connection to the head. If you find a cool one, pull the plug and check for spark. With a new plug, try swapping a plug wire with another cylinder and see if the cylinder is firing. If you see it has spark and it still misses, you may want to check compression. Only thing left is gas and you could swap injectors.

BTW how is your fuel pressure??? Changed the fuel filter lately??? Have you run it low on fuel lately?????