I have a 1998 Cavalier, 2.2l 4-speed auto trans. The car will start and run but sounds like it has a severe miss. It has a rough idle and as soon as you tap the gas pedal it will bog way down and almost die. Here is a list of parts I have already replaced. Two new coil packs, ignition control module, plugs, wires, map sensor, fuel pressure regulator, fuel filter, coolant temperature sensor, and crankshaft position sensor. The only code coming up on diagnostic is random misfire. I am out of ideas and was told it could be the speed sensor? Don't really want to buy anything else that might not fix it. Thoughts? The car is also running EXTREMELY rich. Thanks in advance if anyone has any ideas.

 

How many miles on this motor?How long have you had this problem?what was the condition when the problem first occurred?Be as detailed as possible.I noticed you didn't change the O2 sensor according to your list,Did you have the Head off this motor?

CC

 

Im thinking Converter is plugged up.

 

The plugged converter makes sense. When they go really bad, the honeycomb mesh inside comes apart in a large ball shape. Sitting & running softly, the exhaust gases can pass over it, but then when you start accelerating that ball gets push back by larger amounts of exhaust pressure or the momentum of the car moving forward, then the loose ball rolls to the rear of the converter choking it off & causing a very rich situation. There are no emissions tests in my state, so I usually cut them out & replace with a piece of pipe never deal with them again, but if they test in your state, you need to get a new one put in. This exact problem has happened to me on a few vehicles of various brands. Most exhaust shops will do a free back pressure test to determine this, or you can jack it up & support it safely then crawl under it & knock on the cat like you would a door. In my case, I could hear the ball inside the cat thumping about when I knocked on it. I hope this helps!

 

also take off your EGR valve, it might be clogged going inside the head, take long skinny wire brush, and vacuum out all the carbon. Mine was clogged, and my catylatic converter was also clogged. I have a 93 for 11 years, it idles rough at stops, due to my 3rd cylinder with low compression. Exhaust valve is stuck open.

There is also a tube inside the intake, and mine was clogged solid when i cleaned my intake a year ago.

You have done everything on your intake part of your motor, so i guarantee your motor is not breathing out the exhaust.

 

Thanks for the suggestions and sorry it took me so long to get back. Vehicle is still not running good, haven't been driving it but that needs to change as I just snapped the timing belt on my spare vehicle. There is practically no vacuum in the engine which makes me think either the intake gasket is leaking or maybe it jumped time? What are your thoughts?

 

Plugged converter will result in no vacuum, too. I'd disconnect it and see how this engine runs without it (be prepared to hear some noise).