I have a 99 Camaro V6 3.8. It has 135,000 miles but only 53,000 miles on the replacement motor. I started having trouble a few weeks ago. It rides very rough, especially under any load. It tends to die on me when I'm not easy on the throttle. When idling it will run fairly smooth except the tach will spike randomly every 10 seconds or so (this also happens when I'm driving). It has gotten to the point that it is undriveable. The trouble codes are missfire in cylinder 1 and a bad catalytic converter. I have replaced plugs, plugs wires, ignition coil, ignition control module, catalytic converter, and the crankshaft position sensor. Fuel pressure is fine. There seems to be no problems with fuel delivery. What can I do to fix this problem?

 

Try moving your #1 injector with another one and clear the codes and see what comes back. You my want to run a compression check.

 

^^ agreed

 

The misfire explains the bad cat. Fix that first or your just gonna keep replacing cats. A bad cat from the misfire wouldn't happen if it wasn't getting fuel. Check plugs wires and then coil. To test coil switch the coil to another one and see if the problem follows.

 

Who said the injector was starving the motor? Leaking injectors are more common then dead injectors. He already replaced plugs, wires and coils moving the new part around is not going to help him much.

 

^ Is a leaking injector one which has bad O-rings?

 

I'm curious how the system can pinpoint a misfire in one specific cylinder because of a bad injector, when the oxy sensor is monitoring an entire bank of cylinders, not individuals? What am I missing?

 

My guess is the spark module monitors the Primary voltage feeding the coil and it has a defined range. Above or below that range it assumes a miss. It is not unlike a scope just much simpler. It is looking as average volts at a give time frame instead of mapping a pattern like a scope would.

In theory this type of miss detection could be fooled. A rich cylinder is very easy to fire and may say miss fire when it really did fire. Same would be true for say a coolant rich cylinder. Its saying miss fire but it might be firing just firing and much lower voltage than normal (out of the normal range).

When GM trained me on their new DIS (1987 LOL) system this was not an option back then but it seems not to hard to do since each coil has its own firing system.

 

I'm with you there, so you're suggesting a voltage issue with an injector can be detected? Basically my earlier question I was getting at though was how can a poor flowing or leaking injector (as you suggested) get detected to a specific cylinder misfire?

 

I did a compression check and everything seemed normal.*
I forgot to mention that I have also been getting codes for low circuit voltage 1-4 2-5. Also, the crankshaft position sensor was the last thing that I replaced and the car ran good after that but the next day it showed minor symptoms and the engine light hasn't come back on. I am driving it as little as possible so that the problem doesn't get worse