I was driving in traffic the other day and all of a sudden I felt a shudder and the car started running very rough. When I press on the gas the shudder gets worse and it seems like one of the cylinders are not firing. If I step on the gas hard the check engine light flashes. I checked the plugs and there are no miscolorations and there is no oil on the plugs. Could it possibly be an ignition coil or an injector? Is there a way to trouble shoot this problem. I dont have a tool to plug into the computer.

 

Is the Check engine light on at all or does it only flash? If its on you can get the code read and find out what one is the cause of it.

 

it may be bad gas. Did you fill up recently before this event?

 

The check engine light has stayed on since I have a bad cat, but the car ran fine. Now flashes on moderate acceleration. I didnt fill up around that time, and I have since put more gas in it.

 

I dont have a code reader. How can I get the trouble code?

 

Help anyone??

 

Autozone or similar will pull the codes for free.

 

That will work. Thanks.

 

Well driving around with a bad cat isnt good either. It will cause the computer to really try to compensate. Get whats wrong fixed. CEL's arent just dummy lights. They mean something is wrong and needs to be fixed. Prolonged driving with it on can lead to/cause other things to fail. Just because it seems to be driving properly doesnt mean it is

Most auto parts stores read codes for free

 

Point taken. I will check it out on my way home from work. Thanks.

 

Get the codes read and let us know what they are, we should be able to answer any questions then

 

Start with a new cat and some Seafoam
Could be plugged exhaust and that can be REALLY bad thing!!

 

If everything else is OK, and the cat is plugged because the car is only ever driven short trips, then you may be able to unplug it by getting the cat hot enough to burn off the deposits clogging it. Tow a trailer, or load it up with weight, then do freeway speeds up the biggest hill you can find for a while. This will get the exhaust gases hot enough to do the trick. Watch the temp gage while you do this to avoid other problems.

 

The trouble codes are all cylinders misfiring except cylinder 1 and the O2 sensor in the cat. The car doesnt really do many short trips...I doubt the cat is plugged but I do have a lot of miles so who knows.

 

How do you know it's bad? Do you mean fluffy shat in the gas tank? I know, not funny...
Let's back up...
You said in traffic... So it idles roughly? How does it run at cruise?
If it's only at idle or small throttle openings, a common cause is a stuck EGR valve causing a vacuum leak.
If it's all the time, that points more towards a problem with the ignition system.

 

Odds are you have just 1 coilpack bad. Buy 1 new one and replace just 1 at a time till that code is gone

 

I took it to a mechanic who checked the trouble code and he told me the cat was bad. Now after reading the trouble zones at Autozone maybe it was just the O2 sensor in the cat. It runs rough at all times...it just happen to start when I was in traffic. It runs like if you disconnected one of your plug wires. I am thinking it is ignition related as well and the engine misfiring trouble codes seem to point towards that.

 

I was hoping it would be something like that...but would it cause trouble codes in 4 other cylinders as well?

 

If it's ignition, the misfire means there's more o2 getting to the sensor than it expects, so it would throw that code. Don't replace the o2 sensor unless it still throws the code after you've fixed the miss and the codes have been reset.
Kris is the expert, I'm going with him on the coil pack.

 

i would do what chris suggested. coil pack.

 

Thanks guys. I will keep you posted.

 

Yes. For some reason on our cars 1 usually triggers all 6. )2 sensors have been known to trigger it as well

 

Ok I am off to buy a coil and swap them one by one. I will let you guys know the results.

 

So I go to the dealer to buy a coil and I run into a friend that works there. He has the mechanic look at my car before I buy the coils and the mechanic turns up another trouble code...the EGR and the mechanic thinks that is the source of all of the problems. I am waiting to get a price on repair. What do you guys think?

 

I go to Ebay and buy a coil on a hunch and low and behold it solves the rough running problem. I still need to change my O2 sensor which is on its way but al least its running like a new machine. Thanks for the advice guys.

 

The O2 sensor probably doesn't need to be replaced.
The miss was causing it to throw that code.
Reset the codes, the O2 code should go away.

 

The O2 sensor actually was bad before the misfire.