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Multiple Misfiring

7K views 15 replies 9 participants last post by  Caddytech88 
#1 ·
Update to a previous post on shaking. Codes are P0300, P0302, P0304, and P0411(Air injection system fault). Spark plugs are less than one year old and valve cover gasket was replaced with the plugs, it was leaking at the time of replacement and the spark plug holes and coil boots were soaking in oil when it was replaced. Belts and water pump were also replaced.

Seems like the problem should either be the coil pack on the even side or maybe the fuel injectors. Anyone got an easy way to tell? I didn't really want to run injection cleaner through a tank of gas and risk damage. But I'll do what I gotta do.

Thanks, your advise has always been helpful.
 
#2 · (Edited)
In the future, it's best to keep all posts regarding the same issue in one thread, don't double post.

Codes mean nothing without definitions. Always include definitions when listing codes. You can find an index of OBD II definitions here:

http://myweb.accessus.net/~090/dtcobd2p.html#pow

P0300 - Engine Misfire Detected
P0302 - Cylinder 2 Misfire Detected
P0304 - Cylinder 4 Misfire Detected


I'm not too farmiliar with Cateras. Do cylinders 2 and 4 share a common coil?

You can check for spark to the dead cylinders by using a spark tester tool (very inexpensive, available cat any parts store).

Check if the injectors are working by using a mechanics stethoscope to listen for rhythmic ticking. You can also listen by placing the end of a long screw driver against the injector, and your ear on the end of the handle.
 
#3 ·
If you had only a single cylinder affected, it would be relatively easy to zero in on the problem. Check the usual stuff that could affect multiple cylinders - wet ignition wire bundle, for example.

I like your idea of tying something simple first. I throw a can of STP gas treatment in the tank every now and then. It is supposed to absorb any water that may be in the tank (I believe it is mostly alcohol). Or, as you suggest, you can try the fuel injector cleaner (which I also think is about the same product as the gas treatment). I didn't know there was any "risk" in using these products. Once you have tried that, you can always continue to look for things in common - bad coil pack, or hopefully not a bad injector.
 
#6 ·
Cly #2,#4,#6 share a coil pack. these 3.0 engines go through plugs so a year might be time to change if you put a considerable amount of mileage on it. and although many argue with this point but the manual stats to use Premium gas, if you use a lower octance performance can and will be sacrificed.

Seafoam. Used it in over 50 vehicles over the years.
1/3 in the gas tank
1/3 into the oil crankcase 100miles before an oil change
1/3 into the Brake booster vacuum hose

I always do 50 tank and 50 vacuum, make sure it sucks a good amount into the brake vacuum hose while the engine is running, and then shut it down to sit for 5-10minutes, reattach the booster line and let it run for a few minutes (this part is rather embarrassing as large amounts of carbon buildup usually burn off), take it for a drive come back do it again, it took 3x times before the carbon build up was gone on my Catera. I 100% guarantee an improvement in any vehicle that's how well it works.


-Change your coil, seafoam it, change the plugs and use premium gas and watch how different the car performs.
 
#8 ·
Hey everyone, Thanks for your help. Turned out once I took the coil pack off there was a little bit of oil, but mostly water in the bottom of the spark plug well. I recently changed the valve cover gaskets because they were leaking. There was some white creamy stuff on the rubber coil boots, and also some built up under the oil cap. Would a head gasket leak be able to cause water to get at the spark plug wells? I can't imagine the engine got water on it.
 
#13 ·
that's possibly the dumbest things I've ever read. keep your personal biased comments to yourself.

I guess that's why certain vehicles that have less build up smoke little to none at all. lets forget the obvious notice in performance.

also note cars that use conventional oil tend to have more buildup while as synthetic oils don't. my EXPERIENCE on the several dozen vehicles ive used this product on never fouled a single plug... its petroleum based.
 
#15 ·
RPerry435 said:
that's possibly the dumbest things I've ever read. keep your personal biased comments to yourself.
Please explain what makes it dumb. And it's not personal and biased- Where, other than in their own advertising, advertising by a company they sponsor, or "some guy" that says it works great, is there any documentation that proves Seafoam works as advertised? I've certainly never seen any. Seafoam is good for cleaning parts, not something that should be run through an internal combustion engine.

I guess that's why certain vehicles that have less build up smoke little to none at all. lets forget the obvious notice in performance.
How do you know which vehicles have more or less buildup? Have you disassembled them, or used a snake/inspection camera? Seafoam produces whiteish smoke....carbon buildup burns black...do the math.

Do you have before and after dyno results, or before and after drag strip time slips to document this "obvious notice in performance"? The seat-of-the-pants-dyno need not apply.

also note cars that use conventional oil tend to have more buildup while as synthetic oils don't.
Are we talking about sludge buildup in the crankcase, valvetrain and oil passages? Synthetic oils have a higher detergent level....but what does that have to do with Seafoam? Or are we talking about carbon buildup? In which case, the oil has nothing to do with it.

my EXPERIENCE on the several dozen vehicles ive used this product on never fouled a single plug... its petroleum based.
It can foul plugs. Just like allowing it (or any liquid) to be sucked into an internal combustion engine can hydro lock and destroy the engine. It might not happen, but why chance it?

Why haven't ANY of the words automobile or engine manufacturers caught onto this miracle liquid? Why isn't it's use recommended in the owners or service manuals as a regular maintenance item? You'd think such a beneficial product would get noticed sooner or later huh?
 
#16 ·
Just fought this problem on one... Try swapping the pre-cat o2 sensors. Turns out on mine, the fuel trim on bank 2 would go down to -25%, indicating a rich condition on bank and shutting off bank 2 injectors. Turns out the o2 sensor was providing false readings. This false rich reading also indicated the air injection system was not functioning properly.. When ou swap the sensors, monitor short term fuel trim and misfire data and see if the problem moves to other bank. Easy test and easy repair.
 
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