Cylinders 1-5 Misfiring!

[001Stunna]

had the same problem a few years back, 2 years i think. started with a simple p0420 code. then it went to p0420 and random misfire. then it went to p0420, random misfire and multiple cylinder misfire. unless your car is undrivable, id suggest you wait until something breaks. p0420 is an undiagnosable code. so far ive replaced a cat, cleaned egr, replaced egr gasket, cleaned IM and TB and replaced both gaskets, replaced pcv and pcv grommet, used seafoam, used multiple fuel injector cleaners. i got tired of throwing money at it, so im gonna wait. occasionally it will stall out when i try to start it but thats occasionally. word to the wise, EVENTUALLY, THE CULPRIT WILL BREAK, AND WHEN IT DOES, ILL BE THERE!!!! goodluck though

Huh how is p0420 undiagnosable? Most likely it'll go away if you replace your catalytic converter and check/replace your rear o2 sensor. An aftermarket converter can/will still throw the p0420 code and sometimes a defouler is suggested to be used. After all it is the sensor reading that causes the code to come up. All the other stuff you did was just extra...but still probably worth it in the long run. After 98/99 i believe the v6 had coilpacks so give those a check as well while doing the plugs

So what's causing the misfires?
It's driving like normal, had a slightly rough idle but the pcv valve fixed that.
Did you change the o2 sensors? On the slip they gave me with the codes it said that could also be a problem with the p0420 which is what I have along with the misfire codes.

The codes I'm throwing are:
P0420-Catalyst efficiency below threshold
P0300-Random misfire detected
P0301-Cylinder #1 misfire detected
P0302-Cylinder #2 misfire detected
P0303-Cylinder #3 misfire detected
P0304-Cylinder #4 misfire detected
P0305-Cylinder #5 misfire detected

For the p0420 code...first check to make sure it is not the o2 sensor giving a faulty reading. The next thing would be to check the pressure before and after the converter to see if its indeed blocked but that may be hard for a DIY. I'd say just replace the cat.converter with an after-market and throw a spark-plug non fouler on it before placing the o2 sensor back on. Keep your OEM converter and do not let the shop just take it as worst case you can always sell it for metal. Most places around me will pay anywhere from 40-60$ for one.

As for the misfire code, try throwing in some fuel injector cleaner and recheck. Check replace spark-plugs. Check compression while doing sparkplugs and lastly check fuel pressure.

 

[RichBinAZ]

It could well be the oil you were finding in the inlet. Sucking that thru the engine could coat the spark plugs, mess up the converter and the O2 sensors.

If you think you have the oil sucking problem fixed, keep driving it for a while and perhaps it will clear itself - specially as you said you changed the plugs (i think)

 

[uhhkilleez]

I replaced the spark plugs a couple months and I noticed the oil inside the intake a couple weeks ago, but who knows how long it's been in there.
How should I check if the o2 sensors are bad?
I'll check the plugs when I get a chance, but how do I check the compression?
When I got off work today I filled up and poured a bottle of STP gas treatment in the tank and when I started the car, the light wasn't on. I'll get it scanned tomorrow to see if the codes are still stored.

 

[AccordUser]

Huh how is p0420 undiagnosable? Most likely it'll go away if you replace your catalytic converter and check/replace your rear o2 sensor. An aftermarket converter can/will still throw the p0420 code and sometimes a defouler is suggested to be used. After all it is the sensor reading that causes the code to come up. All the other stuff you did was just extra...but still probably worth it in the long run. After 98/99 i believe the v6 had coilpacks so give those a check as well while doing the plugs.

I meant undiagnosable in terms of "the code not telling you what part is bad." The p0420 doesn't call for the catalytic converter to be replace, but it's where honda and most other shops would start. Some if not most people replace the cat but the code still comes back, like myself. ive just learned to live with it, and wait. yea you can add a defouler but thats only covering up the problem, not fixing it. i would only do that if I was in a city where you have to keep your emissions up. sorry i didnt make myself clear initially.

 

[uhhkilleez]

I meant undiagnosable in terms of "the code not telling you what part is bad." The p0420 doesn't call for the catalytic converter to be replace, but it's where honda and most other shops would start. Some if not most people replace the cat but the code still comes back, like myself. ive just learned to live with it, and wait. yea you can add a defouler but thats only covering up the problem, not fixing it. i would only do that if I was in a city where you have to keep your emissions up. sorry i didnt make myself clear initially.

Mine said something about the catalyst being below threshold in bank one.
Wouldn't that be something like the o2 sensor?

I live in Detroit so no smog checks here.

 

[001Stunna]

I replaced the spark plugs a couple months and I noticed the oil inside the intake a couple weeks ago, but who knows how long it's been in there.
How should I check if the o2 sensors are bad?
I'll check the plugs when I get a chance, but how do I check the compression?
When I got off work today I filled up and poured a bottle of STP gas treatment in the tank and when I started the car, the light wasn't on. I'll get it scanned tomorrow to see if the codes are still stored.

You can check the o2 sensors using a Live Data scanner and looking at the graph for the o2. The front should oscillate betwen 0.2v and 0.8v where as the rear should have much less variation and seem more stable...if the cat.converter is working properly. If the rear seems to not move at all and be at 0 though or at max voltage then it means your converter might be ok and its the sensor that is bad.

For compression, you need a compression tester(cost about $20 here). Take all plugs off, disconnect fuel pump fuse and distributor plug so no fuel or spark can occur. Check the compression in each cylinder twice for consistency and write down the values on a paper. Do the test while pressing on the gas pedal all the way down and cranking the car about 5-6 times each time. Make sure to relieve the pressure each time before un-threading the tester and lube the tester oring with some oil so it doesnt get stuck in the sparkplug hole.

I meant undiagnosable in terms of "the code not telling you what part is bad." The p0420 doesn't call for the catalytic converter to be replace, but it's where honda and most other shops would start. Some if not most people replace the cat but the code still comes back, like myself. ive just learned to live with it, and wait. yea you can add a defouler but thats only covering up the problem, not fixing it. i would only do that if I was in a city where you have to keep your emissions up. sorry i didnt make myself clear initially.

P0420 means your ECU deems your cat.converter to be working under the standard where the ECU expects it to work. It does this by looking at the o2 sensor data. Does this mean the converter is bad? NO; Does it mean the O2 is bad? NO....you have to test/check each one.

It simply means that if the ECU expects the converter to work at 90% efficiency minimum and if it is working at 85% then the CEL will come on.

Most aftermarket converters from my experience are never as good as OEM, and within 1-2 weeks the CEL will come on. Placing a sparkplug non fouler simply means you avoid getting the code hence when something does trigger a code you WILL know & you wont just think its just the converter code on there and nothing else and not pay attention to it.

..............
PS. If you do not want to spend major $$ on a scanner consider this
Go on ebay and buy any one of the "v1.5 OBD2 Bluetooth" code scanners
http://www.ebay.com/sch/i.html?_sacat=0&_from=R40&_nkw=v1.5+obd2+bluetooth&rt=nc&LH_BIN=1
Sort them buy price+shipping lowest and just buy the cheapest one. They're all the same sh1t.

As long as you have an android phone/tablet etc you can download "Torque" app for free and use it for checking/clearing codes/reading live data/and graphing parameters. It is not as fast at updating data as an actual tool is but its better then nothing and cost you only 10-20$. I personally bought the smaller plug and just have left it plugged on and have a cheap android phone I don't use anymore just sit in my arm-rest cubby whenever I want to see something.
You can also use it with your laptop as long as it has a bluetooth connection(if not buy a dongle for 1-3$) and get yourself ScanXL Standard or look around a bit and you can find the Professional for free too. http://www.palmerperformance.com/products/scanxl/index.php

 

[uhhkilleez]

Thanks a ton for all the helpful info, I'll be doing all of this when I get a chance to and hopefully it'll fix my problems.

 

[AccordUser]

got an update? not sure of this thread is dead yet...

 

[uhhkilleez]

got an update? not sure of this thread is dead yet...

Have't taken care of the problem yet, been swamped with school and work.
The light will be on for a day or two and then randomly turn off. Then it'll come back on in a day or so.
I never feel it misfire, when the light comes back on it's usually when I start in in the morning.

A couple days ago I was driving the car fine all day then when I got in and started it to go to work (engine was warm and at operating temperature) it shook and idled real rough and stalled. Waited a few minutes then started it and had to rev a little to keep from stalling.
Once the idle smoothed out it drove completely fine.
Had to start it again a little later and had the same problem.
Got to work, bought a bottle of STP fuel injector cleaner, poured it in the tank. Started the car about ten minutes later and it started up fine.


Could this be from the misfire or something else like clogged fuel injectors?

 

[AccordUser]

Have't taken care of the problem yet, been swamped with school and work.
The light will be on for a day or two and then randomly turn off. Then it'll come back on in a day or so.
I never feel it misfire, when the light comes back on it's usually when I start in in the morning.

A couple days ago I was driving the car fine all day then when I got in and started it to go to work (engine was warm and at operating temperature) it shook and idled real rough and stalled. Waited a few minutes then started it and had to rev a little to keep from stalling.
Once the idle smoothed out it drove completely fine.
Had to start it again a little later and had the same problem.
Got to work, bought a bottle of STP fuel injector cleaner, poured it in the tank. Started the car about ten minutes later and it started up fine.


Could this be from the misfire or something else like clogged fuel injectors?

That is a good question. Hopefully somebody on here has some insight. Bump.