Random Misfire Code and Cat Code

Hey guys, I was reading the other thread down below and I am really suprised that I am not the only one dealing with this problem. So here is the info:

2001 Mazda Protege ( dont remember off the top of my head what specification it is like es, lx, whatever)
almost 120k on it.
bought it from a dealership 4 months ago.

I was driving it around for a week after I got it. And the CEL came on blinking. I don't remember what the symptoms where. But when I saw it I pulled over. The rpms where going down and the car was shuddering and I turned it off. Let it sit awhile like a few mins. Then turned it back on, it was fine, and the CEL was on just not blinking. So fast forward 4 months of that happening very often. I got the CAT replaced, and now both O2 sensors replaced at the dealership's shop.

Now I drove it off the lot yesterday hoping that the problem was solved. I turned around because I forgot some stuff in the loaner car that they provide and the CEL was blinking AGAIN!! When I drive though it the rpms kinda shudder if I slow down and stop at a light, but that is all. Then the light goes from blinking to solid. So they people at the shop pulled the code and it was a Random Misfire. They cleared and said just drive it. They said that they drove it a week and never got it to misfire. So then last night I turned on my heat and right when I did that the CEL came on, called the mechanics and they said to bring it in tomorrow. So when I was driving today down the highway at 69 mph I felt a little jump or something and I knew it misfired and it did. When the codes where pulled it said Random Misfire and CAT (don't know the specific codes I will get them here later for you all).

So with all the info can anyone tell me whats wrong with this car?? :)
thanks a bunch.
 
Hey guys can I get some support in this, I really want this fixed.

HereThe code for the Catalytic Converter has come on more frequently. And I remembered that the random misfires didn't happen until I got the cat replaced. And the mechanic said that the code from the cat means that it is bad again and needs to replaced. But it is warrantied so no biggie.
 
Hi Guys !
I had the same problem a month ago, with my GF's car, a Protege 2002 LX 2.0.

I solved the ramdom misfire P0300 by changing the spark plugs and both coils. and I changed the Cat and that fixed the P0421 code (cat effeciency below treshold).
 
Had similar problems P0300/P0302 and P0401. Did the coils and plugs and wires which didn't help, the problem was the EGR valve wasn't opening and closing properly. Maybe clean out the EGR valve or get it replaced, it fixed my problems. Good luck.
 
plugs/coils didn't work for me either.

my issue is with the EGR as well. I just have yet to get back there to get it off and clean it
 
I wouldnt think a dirty egr can cause a mis-fire, but wont cost anything to try it.

Is the gasket re-useable?
 
egr will cause the stumbling idle which could in turn possibly cause a misfire
 
In my case, at 82,000 miles my first stock ignition coil went out. I replaced it for $18 at Autozone, but since I ran it for a while misfiring, I then got the cat code and replaced my warmup cat. The catalytic converter had a one month warranty. 32 days later my other ignition coil went out and I had to pay for another cat. $900 in one month. Ouch! (smash)
 
funny thing with mine is it runs fine and smooth, and I get no MIL light at all. I just noticed the n0. 2/3 clyinder coil pack was firing intermittently when i put a timing light on no 3 cyl ignition lead.

I decided to just drive it like it is, i cant find anything wrong with it, the only thing left to check is the signal from the ECM to the coil pack,
 
yes the gasket is reusable pulled mine off..it's just a thin metal gasket...that's all
 
Had similar problems P0300/P0302 and P0401. Did the coils and plugs and wires which didn't help, the problem was the EGR valve wasn't opening and closing properly. Maybe clean out the EGR valve or get it replaced, it fixed my problems. Good luck.

+1
plugs and coils and wires didn't do nothing for me either... and my egr tube is currently bent in two places (i know not a proper seal but my exhaust manifold doesn't have an egr hook up)... im going to put an egr block plate as soon as i find some time...

well actually just really lazy cuz the egr is a PITA to remove
 
so does anyone know what blocking the egr will do or not do? it a good thing to have....bad.....does it change anything
 
well as i explained mine is sorta blocked off... and so far no new problems except the original problem... and this was going on ever since i put in my second motor... before going turbo the problem existed... idk never happened on my first motor
 
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