I think I have an explaination on my misfires.

[Mogobs30th]

I believe that my misfires are caused by a clogged cat. Here's why:

1. The engine only seems to misfire when I accelerate or maintain a certain speed above 1500 rpm. When you accelerate or maintain speed, you have more exhaust coming through the cat converter. So with the cat being clogged, the exhaust gases are getting trapped and coming back through to the engine.

2. I ran an OBD tool on my car and it came up with a code (P0300) which means random misfire or misfire detected. Nothing more specific like a cyl number or sensor going bad.

3. This problem has gotten progressivly worse as the car gets older. I bought the car with 51,000 miles on it. When I first bought it, it was trouble free. After putting about 15,000 miles on it, it seemed to misfire on and off on rare occaisions. It now has 93,000 since I bought the car in Feb of 2000, and it ALWAYS wants to misfire. I now have to take it easy on the gas or it sputters and chokes like a *****.

4. I have replaced every part of the ignition at least once; ign. module once, coil packs once, wires and plugs 4 times. It can't be the ignition.

Although I know that it can be any number of things, this is what I am leaning towards. Just needed to know if there is any information that I am missing and if this theory is correct.

Thanks

[ November 20, 2002: Message edited by: Mogobs30th ]</p>

[Blackbird3800]

i had that same prob for a while.....you need to have the fuel injectors cleaned by either the dealership or any place that will hook up to the nozzle on the fuel rail and use a high pressure tool to really clean thoes out , then is should run great , after all that you need to start using quality gas like Chevron w/Techron 92 octane , and the problem shouldnt reappear.....hope i helped :D

[blackfire99]

well, i had a misfire along with 4 other codes and it was a clogged cat...for temporary relief, i cut it out and knocked the insides out with a rod and a hammer...it was really clogged bad! it runs great now, no ses light, and the o2 sensor has yet to go out on me...pretty easy fix...if you want, you can buy a new cat for $50 or so...but why, mine seems a little more open than it did and souns pretty good.

[XtreMeCamAro]

I had a problem with my car misfiring I pretty did what you did and still the same problem, weird and all i had to change the gasket to my timing cover when i toke that s.o.b off in noticed that my timing chain had jumped a link on the gear so i went ahead and changed the timing chain and gears figuring i already had the cover off so i might as well do it, well guesse what after i put the car back together and started the car up no mis fires and the pick up was even better mind you i only have 82,000 miles maybe that can be your problem just a suggestion.

[SuprSpdDB7]

<blockquote>quote:</font><hr>Originally posted by Blackbird3800:
i had that same prob for a while.....you need to have the fuel injectors cleaned by either the dealership or any place that will hook up to the nozzle on the fuel rail and use a high pressure tool to really clean thoes out , then is should run great , after all that you need to start using quality gas like Chevron w/Techron 92 octane , and the problem shouldnt reappear.....hope i helped :D <hr></blockquote>

how much does this usually cost?

[BillyCobin]

I am having the exact same problem right now, but mine isn't to the point of stuttering when I get on the gas. I have done some research on the cause, although most of it has been suggested in this thread, I'll try to put it all together.

1) Of course, for misfires, the first thing is to replace plugs+wires, and test the other ignition parts. You have done it, so no worries there.

2) Make sure you are getting enough fuel. Replace fuel filter, check fuel pressure, have injectors cleaned.

3) Clogged cat causing too much back pressure. Any exhaust shop would be able to check this for fairly cheap.

4) Timing chain, this one I don't know how to check, other than pulling apart the engine. This one looks like the most costly of the causes, and I think its what is wrong with my car.

Good luck.