Rough idle code p0302 & p0420..

[RUNNINIT]

Hello again got a new problem yaaaa!!! well it WAS running fine just. replaced MAF put new plugs,air filter,fuel filter about 2 months ago ran perfect until the other day. now my CEL is on and it's idling rough codes are p0300 p0302 & p0420 not sure what these mean exactly but i think the p0300 means multiple cylinder misfire and p0302 means cylinder 2 misfire i can't remember what p0420 meant. I think i going to try some new wires and see what that gets me if not maybe try switching the coil packs around. anyone else have any ideas. If you do i would appreciat the feed back.. thanks

 

[toto]

P0420 is a code for the Bank 1 Catalytic Converter output. Sometimes the computer intentionally messes with the air/fuel mix to see how the cat responds and if the O2 sensors respond accordingly. The code means that the O2 level coming out of the cat is wrong for what the computer thinks the air/fuel ratio is going in to the engine.

I wouldn't assume the problem is the cat - it's probably connected to the misfires somehow. (Yes, P030x is a misfire on a given cylinder, and P0300 means more than one misfired.)

Which year and engine do you have? That information might trigger some more thoughts.

 

[RUNNINIT]

Thanks for respponding! It is a 2000 limited 4wd with a v6. Do you think it might be a coil pack? is cylinder 2 on the same side as the coil packs ?

 

[jimlaw3]

P0420 is a CAT problem,when you have misfire codes P0300 is multiple misfire,P0301 is cylinder 1 and so on.Misfire problems will cause CAT damage because unburnt fuel is getting into the CAT,get your misfire fixed asap.You may need a CAT.I replace alot of CATs because of this,I am a Honda Tech and when I have a code P0420 it needs a CAT period.Maybe its different for the Toyotas,hopefully.Good luck.

 

[RUNNINIT]

Thanks for the response jimlaw3 I hope it's not the cat either. I just replaced the plug wires tonight and diconected the battery. the CEL is off but i still have a rough idle id does seem to be a little better or maybe just different cant really tell. throtle response is almost better though and power is still good. Anyway i do have a couple of questions if anyone can help that would be great.
1. It has been really cold here for the last couple of weeks like a high of 0 and lows in the -10 to 20 degrees so i have been letting it warm up for a while before driving off. question is would this hurt it in anyway or maybe damage the cat letting it idle.

2.Does anyone have a diagram showing where cylinder #2 is

3.Does anyone have a good place to order parts.

THANKS IN ADVANCE..

 

[RUNNINIT]

I almost forgot. Does anyone know how to check a coil pack and what the specs are supposed to be? same thing for the injectors... THANKS

 

[BobLMTDT4R]

Runninit: I've having the same problem, minus the p0420 code. I'm constantly throwing the P0302 code and I have done everything except tear into it...which apparently I am this weekend. I was told by a friend who is a mechanic to swap the injector with anyother one...if the code follows...problem solved....if it doesn't, bigger problem.

Bob

 

[RUNNINIT]

Hey Bob, I'm still having trouble with this I did however decide to fill up with premium fuel instead and it stoped idling rough and my check engine light went off and everything was fine until I filled back up with some 89 octane and problem came back and CEL came back on lastnight again. I dont think it's the fuel. Probably a coincedence. I dont really know what to try next. coil pack,new injectors, cat, o2 sensors??? What all have you tried???

 

[BobLMTDT4R]

So far I've done: New Cat and Muffler (needed them anyway), New Coilpack, plugs, wires, cleaned throttle body, MAF, used fuel additive/cleaner, did a compression test...only thing left to do for me is to start tearing into the engine. So far I think I have it narrowed down to the injector. I just want to do more research before I go forking out $125 for an injector and find out its not it.

Best thing to do is start simple, then start the more involved after that. I wasn't getting the 420 code, so I don't know what that would be.

I'll keep you updated on what I find also.

Bob

 

[RUNNINIT]

Please do keep me updated I cant decide what to try next. if anything i might try a new 02 sensor. Not sure though. because I dont know if my misfire is causing the 420 code or the 420 code is causing my misfire. I might just take it to the stealership and have them run a diagnostics check see if they can narrow it down for me. I am running bosch plugs that i just put in 4 months ago. I didnt know there was such a big difference in plugs but from what i read on here i should probably change them. I did pull the plugs on the passenger side lastnight and they look fine still looked new. Anyway's I'll keep you posted too.

Charlie

 

[RUNNINIT]

Update

Please do keep me updated I cant decide what to try next. if anything i might try a new 02 sensor. Not sure though. because I dont know if my misfire is causing the 420 code or the 420 code is causing my misfire. I might just take it to the stealership and have them run a diagnostics check see if they can narrow it down for me. I am running bosch plugs that i just put in 4 months ago. I didnt know there was such a big difference in plugs but from what i read on here i should probably change them. I did pull the plugs on the passenger side lastnight and they look fine still looked new. Anyway's I'll keep you posted too.

Charlie

So. I finally decided to switch plug with some ngk's since i was running bosch platinums. I should have done this a month ago.. Since I have switched to the ngk's I have not had one misfire CEL has been off for a few days now and it is idling smooth as ever.Thanks for everyones help!!! Maybe next time I will listen to what everyone is suggesting LOL!! Hopefully this did take care of the problem and it stays gone.