I bought this Jeep used and have had nothing but problems!:2cents: First the Crank sensor then the tranny. Now the thing just dies once and a while. I scannd it and came up with code P0300,P0301,P0302,P0304,P0305 and P0306 Misfire detected in multiple Cylinders. Where do I start????:banghead:

Thanks!

Tune up and a can of seafoam in the gas tank. You have to start somewhere and it is hard to diagnose a misfire problem unless you know the condition of the plugs, wires, cap and rotor. Basically it is a process of elimination. You have to give the injector cleaner time to work, sometimes up to 2 tankfuls. If you haven't seen a difference by then it is time to look further.

I just bought my first jeep too. I am baffled by all the different sounds it makes :banghead:
I started by putting in a new muffler and tailpipe, now I need a cat converter I think. Then theres the whirring of the wheels. Ugh.

when my car through those codes it was because my spark plug wires went out. So i would start with plugs and wires.

all the sounds it makes? its a jeep thing you wouldn't understand

I just bought my first jeep too. I am baffled by all the different sounds it makes :banghead:
I started by putting in a new muffler and tailpipe, now I need a cat converter I think. Then theres the whirring of the wheels. Ugh.
Maybe I'm missing something here but what exactly does "putting in a new muffler and tailpipe" have to do with misfire detected in multiple cylinders? That is what this thread is. Sounds like some of you guys should have used mechanic skills to check out these vehicles a little better before you bought them. I bought an 87 Wrangler in May and a 95 GC Limited about a month ago and the only issue I'm having is a vibration at highway speeds in the GC. Nobody else here knows what the vibration is either so I don't feel so bad. I'll bet next time you take someone along with you when you are shopping for a vehicle instead of going into a purchase blind.

I bought this jeep off the internet, so I never saw it. I didnt really care what it needed because I rebuild engines all the time as a hobby. Would you have to see a 65K mile 94 limited 5.2 before you bought it? Im here to tell you its sweet, but I have never owned a Jeep.

Do not mistake my kind, off-topic post as ignorance. :naughty:

a can of seafoam in the gas tank. .

Redneck tuneup:icon16:

Actually I just replaced the wires, plugs, rotor and dif cap. Maybe I got faulty wires? Thanks for the info!

Actually I just replaced the wires, plugs, rotor and dif cap. Maybe I got faulty wires? Thanks for the info!
If you suspect the wires it is real easy to check them with an ohm meter. It is highly unlikely but it does happen. I would be willing to say not as a multiple misfire is indicating more than 1 cylinder. It is more likely to suspect the fuel system as a batch of bad gas will affect more than 1 cylinder. Before you go any further you should do a compression check to rule out an engine mechanical problem. Years ago this was the first thing you would do when doing a tune up. When you removed the spark plugs were they black from an over rich condition or tanish white? An over rich condition caused by a dirty air filter will over time cause misfires. On the other side a vacuum leak depending on where it is can cause a lean condition which can trip codes and light the MIL. If this is the case a can of carb cleaner sprayed anywhere you might suspect a leak will change RPMs while idleing. As far as the sea foam goes I would much rather add an $8 can than spend hundreds on new injectors so don't pay to much attention to people who knock it as it only shows their ignorance and their lack of experience.

To be honest, if it wasn't a MOPAR CPS done at the dealer or by someone who is VERY good at it, I would start there and makre sure its a MOPAR part or one recommended by many on the board. I could not get to mine because it is in a tough spot behind the bell housing on the tranny, so I had to have the dealer do it. Luckily, I know one of the guys there too, so it was cheaper than usual.

I had a CPS go bad on my 1996 Jepp GC and had my regular mechanic put on a new one (not MOPAR). As a result I chased a multiple misfire problem for almost a year and should have listened to my "gut".

They are not that expensive, but VERY quirky in Jeeps....

Bryan

When you removed the spark plugs were they black from an over rich condition or tanish white?

They were black.

I changed the air filter as well.

When it stauls out there is a funny smell that comes from either the exaust or the engine. Iit is sometimes hard to start right after and as i turn it over it still produces the smell. Then it fires up normally?????:banghead:

I can drive it the next day and it will run normally and may or may not staul.

This is a frustrating problem because you never know when it's going to happen.

Anyway, thanks for the advice!