99 V6 camry misfire

[eevee11]

I was driving down the highway the other night, at the end of a 30 mile drive, when suddenly my car started running a little rough. Kept running rough in town, then the next day CEL went on. Check codes with my OBD2 reader, reset CEL, comes back on (still running rough).

codes:

Always I get a p0302
sometimes I get a p0305 and a p0300

these are cylinder misfire codes.

according to my Chilton's manual, cylinders 2 and 5 fire from the same coil.

so I did resistance check on all three coils, primary and secondary circuits are fine for all. Just to be sure I shifted the coils around to new cylinders each, reset CEL, comes back on with a couple p0302s and a p0305 and p0300 (same two cylinder misfires). so coils should be fine.

So it must be cylinder 2 right? or maybe 5 I suppose.
I will next try swapping the plugs between 2 and 4.

what else? is it worth checking resistance on the wires?

fuel injectors?

thanks for any help -

eevee

[chronoti]

also try changing your filter i drove back from miami and got some crappy gas that cloged out my filter .... thew a cel ... change the filter it didnt come back till my o2 sensor went out.

after you change your filter use some injector cleaner too..... hope this helps

[pclemg]

It could be fuel regulator module. I had that go out on my Gen 3 V6 3 times since owning the car (currently 139K). The car would run rough when this module goes out. It usually happens after putting in crappy gas. It cost about $230 to replace the module. Good luck!!

[yellowbal]

What were the symptoms that your fuel regulator module went out?

My gen3 v6 is running rough right now, but mainly on lower rpms. It's very noticeable when in O/D with differential locked and cruising at exactly 50mph (2000rpm). I was just going to change my plugs, but I just changed them 35000 miles ago. I've already changed the 02 sensor and the fuel filter. Hmm...

[eevee11]

yeah, I'm also wondering abouit the fuel regulator - did the CEL (Check Engine Light) come on? Do you know what were the codes?

But I doubt mine is a generic fuel supply problem (like fuel filter, regulator), given that OBD always (and only) reports cylinders 2 and 5 misfires. Injector, maybe, but I'm still thinking ignition.

That's why I'm hoping to hear from someone who has experience with these codes - can I be pretty sure the problem is specific to firing those cylinders? so rule out things like filter and regulator?

Too cold, and too busy, to swap the plugs around yet, maybe tomorrow ...

[yellowbal]

I have no CEL. My car just runs rough, mostly when cold and always when around 2000rpm or under heavy load.

[hydra504]

You know what I have the exact same problem that you have with engine miss fire, when I did the code check I got a MAF senor error and also possible ti could be my spark plugs but i highly doubt it. Check your MAF senor that could be it. I knwo mine is messed up becasue when ever I drove for about 30 miles and got to a complete stop my car was idling very rough and it felt like it wanted to die on me. I'm also complentaing on changing the fuel injectors and fuel pump to a better aftermarket one. But I don't know if that really is my problem.

[pclemg]

It started out as rough idle at a stop. It got progressively worst to the point where I could even turnover the engine. Dealers tends to be more expensive, but the dealer I go to seem to diagnose the problem correctly as opposed to a independent shop that may not. Given that my camry rarely breaks down, it is worth it to have the dealer diagnose the problem. Its up to you what you want to do. By the way, I am certainly not a fan of dealers in general unless warranted.

[hydra504]

Take it to a dealer like pclemg says, they might be able to properly diagnose your problem but you might have to pay some $$$ for it.

[eevee11]

I didn't think it should be a sensor or fuel problem - because always it was cylinder 2 that misfired. And sometimes 5, which fires off the same coil, but never 1-3-4-6.

I pulled the cylinders 2 and 4 plugs, blew off some carbon with compressed air, swapped 'em. problem fixed! Runs like a top again! Cheap and easy solution, thankfully.

I will change all the plugs. That rear bank of plugs looks inaccessible - do I have to take off the air intake to change them?

Anything else I should change (other tune-up items)?

Thank everybody for help.

[Mike Gerber]

I would also check the resistance of the plug wires when you get the chance. New or cleaner plugs require less voltage to fire them. This makes it easier for a marginally acceptable wire to work. It may work fine for a while and then the problem could return. If you have a DVM check each wire for resistance. A general rule of thumb is a good wire will have about 7,000 OHMS of resistance per foot of wire. This is a rough estimate; a little more or a little less won't hurt much. If you find any wires you can't get a reading on; those wires are broken internally and should be replaced. If that is the case, you might as well replace the whole set. Once 1 or 2 go, the others are generally the same age and can't be too far behind.

Mike

[ArmyofOne]

my ford contour did this, at about 298,000 miles. it turned out 2 of my 4 plugs had cracked.