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Discussion Starter #1 (Edited)
Helllpp!!!!

I'm getting a trouble code of P0302 (misfire on cylinder 2) on my 97 Camry LE.

I pulled the spark plug and it has a black shiny(ish) coating on it, including on the electrode. There doesn't appear to be any actual disintegration of the plug, only the black coating. It's not covered in oil, but some of it seemed slightly oily, especially the compression washers at the base of the threads, and there seems to be a light brown discoloring of the porcelein at the base of where the plug boot sits.

Any ideas?

Thanks!

 

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Discussion Starter #3
Thanks.

I forgot to mention that I also previously got a code P0420 (Cat operating below efficiency) although the cat is only a couple of years old and I've only put a couple of thousand miles between the cat swap-out.
 

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Thanks.

I forgot to mention that I also previously got a code P0420 (Cat operating below efficiency) although the cat is only a couple of years old and I've only put a couple of thousand miles between the cat swap-out.
A misfiring engine will lower EGT's, thus, also making the rear O2 pick up a slow signal that indicates a bad catalytic. Fix the coil pack issue and the cat should be good. Don't wait too long or the rich air/fuel mixture from unburnt fuel will eventually ruin the cat as well.
 

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Could the plug wire/injector also cause the P0420 cat below efficiency error?
Possibly. If there was a missfire for any length of time, the unburned fuel in that cylinder (if it was/is an electrical missfire) would make it's way out that cylinder's exhaust valve and through the exhaust system. That means it's going through the catalytic converter. This unburned fuel is pure hydocarbons that can ruin the converter.

Mike
 

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Discussion Starter #9
This all happened pretty quickly. I was driving the car for the first time after clearing the P0420. I'd driven 10 miles with no problem and parked it for 15 minutes.

When I started up again I noticed a loss of power for the first time in the car's history. I'd been driving for about 3 miles when the CEL flashed on-off continuously and I hooked up the code scanner while driving (I keep it in my glove box). The loss of power remained constant and every time I reached a traffic light the car was shaking violently on the verge of stalling out. At that point I was almost home and drove the mile to my driveway and there she sits...

Could this all point to the injector/wire or could it be a bad O2 sensor (even though its just a 10K miles old..)?
 

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This all happened pretty quickly. I was driving the car for the first time after clearing the P0420. I'd driven 10 miles with no problem and parked it for 15 minutes.

When I started up again I noticed a loss of power for the first time in the car's history. I'd been driving for about 3 miles when the CEL flashed on-off continuously and I hooked up the code scanner while driving (I keep it in my glove box). The loss of power remained constant and every time I reached a traffic light the car was shaking violently on the verge of stalling out. At that point I was almost home and drove the mile to my driveway and there she sits...

Could this all point to the injector/wire or could it be a bad O2 sensor (even though its just a 10K miles old..)?
That plug's looking like the mixture is somewhat rich, or you're getting a bad burn in the cylinder. Does the plug smell "gassy"? Check some of the other plugs -- if they look OK, it ain't the O2 sensor (as others have stated, if you're getting a bad burn, you'll get a bunch of unburned junk overloading the cat, which will give you a "cat efficency" error from the downstream O2 sensor).

Start with the simple stuff. Swap plugs -- see if the problem follows the plug. Swap a couple of ignition wires -- same logic. Same for ignitors. Pop off the distributor cap -- check inside for anything funky, like a burned contact or carbon tracking. Doesn't seem likely to be a valve issue, but a compression check is pretty easy to do if none of the ignition system checks turn up anything obvious. If all else fails, try swapping injectors, although that's a bit of a pain in the *ss.
 

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Discussion Starter #11
Thanks for the reply. I'll check all this in the morning. One thing I will say is that it looks like I have a leak somewhere in the valve cover gasket.

My Camry is a 5S-FE 4 cylinder engine CA-Emissions so it doesn't have the distributor, only 2 coil sets controlled by the computer. I've tried testing the secondary resistance and this looks fine. Could the coil pack still be at fault if the resistance looks good?

I'll try the plugs & wires & give it a compression test if I can get my compression gauge back from whoever borrowed it! If I'm using a non-CA cat & sensors in a CA-emissions car, would this make a lot of difference, other than the tolerances? The cat is definately non CA-emissions as when I bought it the guy told me I only needed a CA one if the car was being driven in CA, which is double the price.
 

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Thanks for the reply. I'll check all this in the morning. One thing I will say is that it looks like I have a leak somewhere in the valve cover gasket.
<chuckle> Par for the course -- the valve cover gaskets on the 5S-FE always leak after a while. Easy enough to fix when you've got the time, but it's not causing this particular problem.

My Camry is a 5S-FE 4 cylinder engine CA-Emissions so it doesn't have the distributor, only 2 coil sets controlled by the computer. I've tried testing the secondary resistance and this looks fine. Could the coil pack still be at fault if the resistance looks good?.
My bad -- none of the Gen4 5S-FE rigs have distributors. I spend most of my time dinking with Gen3 rigs, so I tend to overgeneralize. Yes, it's possible for the ignition coil to have it's DC resistance to be OK, and yet be flakey. That's why swapping the ignition coils is a nice diagnostic -- if the misfire DTC moves when you move the coil, you've isolated the problem.

I'll try the plugs & wires & give it a compression test if I can get my compression gauge back from whoever borrowed it! If I'm using a non-CA cat & sensors in a CA-emissions car, would this make a lot of difference, other than the tolerances? The cat is definately non CA-emissions as when I bought it the guy told me I only needed a CA one if the car was being driven in CA, which is double the price.
The rear cat should be the same on CA and non-CA. Only the CA had a front cat, so you wouldn't have an option there. I'm pretty sure the CA rigs used a wideband A/F sensor up front instead of the older O2 sensors, while the non-CA rig just used a standard O2 sensor. If that were the case, 'tho, I'd expect that subbing in a regular O2 sensor for the upstream sensor on a CA rig would never work, since the A/F sensors and the O2 sensors tend to have very different behaviors. The downstream sensors on both CA and non-CA were the older O2 sensors (and this sensor would be what triggers the "cat operating below efficiency" DTC). Whatever the case, the misfire DTC you're getting can't be caused by the cat or O2 / A/F sensors.
 

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I'd been driving for about 3 miles when the CEL flashed on-off continuously and I hooked up the code scanner while driving (I keep it in my glove box).
BTW, that MIL flashing means that the misfire and driving conditions are such that the catalyst could overheat (i.e., you're getting a whole crapload of unburned stuff getting fed to the cat, instead of just the occasional misfire).
 

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Discussion Starter #14
Thanks again!!

I've had the valve gasket hanging up in my garage for over a year now but never bothered to change it yet :lol:

If the MIL was flashing for 10 miles or so, would that be enough to wreck the cat?

Also, as I have the 4-cylinder engine, I have 2 coil packs instead of individual coils. Is it likely/possible that one coil fails as opposed to the whole pack?
 

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I've had the valve gasket hanging up in my garage for over a year now but never bothered to change it yet :lol: ?
I know the feeling -- I've got an A/C expansion valve and scrubber for my Sequoia that's been gathering dust since last summer. Since it's still snowing, I'm still not real motivated to change them out :D.

If the MIL was flashing for 10 miles or so, would that be enough to wreck the cat??
Not likely. The flashing is mainly a warning to fix it now, rather than later (I've known people to run around with their MIL on for months before getting it checked).

Also, as I have the 4-cylinder engine, I have 2 coil packs instead of individual coils. Is it likely/possible that one coil fails as opposed to the whole pack?
Hmmm. Good point -- usually on the coil packs both plugs fire at the same time. I think it's still possible for one internal connection to go south and the other to be OK. I just hate to rule it out based on "common sense" when it's relatively easy to do the swap, and know for sure.
 

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I ordered the compression meter today. All 4 stores in my area were all out of all but the $40 Universal ones. I'll give it a try when it comes in.

I'm not too sure as to whether I can just switch over the coils though. They have discrete part numbers and the 2&3 coil costs more than the 1&4 coil. Go figure... You'd think they were the same part. How can the computer possibly tell the difference, its just a coil and they both have the same resistance...

The only good thing is that I went to start the car up this afternoon and got the same idling problems, which hopefully should make diagnosis a bit easier.
 

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I ordered the compression meter today. All 4 stores in my area were all out of all but the $40 Universal ones. I'll give it a try when it comes in..
In the meantime, did you try swapping spark plugs and plug wires to see if the misfire follows either one? Plugs rarely go bad, but bad plug wires happen surprisingly often.

One other thing...you had mentioned that the valve cover gasket was leaking, and I blew it off, figuring it was the usual light seepage one sees with the 5S-FE. However, if the leakage is really heavy, you might be getting enough contamination into the injector connector to throw things off. Doesn't seem real likely, but it's also not too difficult to get back there, clean up the connectors (inside and out), and reseat them.

I'm not too sure as to whether I can just switch over the coils though. They have discrete part numbers and the 2&3 coil costs more than the 1&4 coil. Go figure... You'd think they were the same part. How can the computer possibly tell the difference, its just a coil and they both have the same resistance....
That's really strange. It'd sure make me leery about swapping the packs.

The only good thing is that I went to start the car up this afternoon and got the same idling problems, which hopefully should make diagnosis a bit easier.
That's cool -- intermittent problems suck.
 

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If u haven't solved ur problem check the fuel injector to that cylinder. Could be leaking.

Have u tried replacing the spark plug to the cylinder that is misfiring?

As for the valve cover gasket leak I was able to fix my leak on my maxima by tightening the valve cover screws. It seems they either all came loose or the gasket more likely shrunk. If u try this be sure not to over torque and there might be a tightening sequence to prevent warping of the valve cover.
 

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And how long is bad? Days, weeks, months? Thanks.

Edit: I read the whole thread and you mentioned some people go for months.. I worry because my old jetta had frequent misfire and by the time i fixed it, over 1 month, after I smog my car this year, the Hydro Carbon was very high..which means my cat could have been damaged.

A misfiring engine will lower EGT's, thus, also making the rear O2 pick up a slow signal that indicates a bad catalytic. Fix the coil pack issue and the cat should be good. Don't wait too long or the rich air/fuel mixture from unburnt fuel will eventually ruin the cat as well.
 
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