I’m a long time member but not much of a poster. And I’m posting this thread for a friend of mine. He has a 2001 tribute V6 that started to misfire. It started about two weeks ago coming back from a road trip. He installed a K&N air filter and was going to change the spark plugs until he took the plastic cover off the top of the engine and saw the intake had to be removed. So he left the top cover off for about two weeks and ran it through a Colorado snow storm. That’s when the misfire started. The other day he was driving through town and it all but died. He had to pull over into a parking lot because he lost all power. Last night I went and looked at it. It had a loose air intake that wasn’t much of a deal. Cleaned the air flow meter, sprayed out the throttle body. It starts fine when its cold and actually idles pretty good. You can tell there is a miss but it doesn’t sound major. You do hear a loud metallic metal on metal kind of screeching, more like a whistle when it starts that lasts for about 30 seconds but I don’t think that is related to the problem. Anyway when its cold you can floor it and it will only rev to about 2400 then it sounds like a rev limiter kicks in. It did have a CEL so I scanned it and pulled a 304, 306/ Misfire on #4 and #6. It wasn’t running too bad so we tried to drive it to the nearest shop a few blocks down the road. We only got it out of the parking lot, then it lost power again and we had to push it back into the parking lot. Now the idle bounces between 400 and 900 and wont rev past 1500. It sounds rough like its only running on 2 or 3 cylinders. When it was running decent I tried unplugging a few sensors to see if it made any difference. There are two on the throttle body. One on top attached to what looks like a little round solenoid and one on the right side. Not sure which one is the TPS. The one on top if you unplug it the RPMs fall and they pick back up when you plug it back in. the one down on the side of the throttle body, when you unplug it, nothing happens. Any way to me it sounds like an ignition problem, like something got wet from the snow. Anybody have any suggestions on what to check for?

 

turns out it was a plugged cat

 

Same thing happened to me. Misfire and plugged cat. The thing is the plugged cat is a result of the misfire not the other way around. I had coils and the cat replaced, oh and the plugs. The misfire somes back again and again and.....

I just posted a thread about this..... I wish I could find the problem. The garages in my town can't figure it out.