Our 05 Rubicon has had no engine work or parts changed since we bought it 500 miles ago. It just turned 82,000 when the ✔ engine light came on, and started running rough. It shows a code P0300. Any thoughts? Part numbers? Thank You! P.S. yes it needs an oil change any recommendations? I take our car & truck to a local family owned oil change shop and it helps with more frequent changes, any real strong reason for other options? Thanks Again!!!
This could be a few things, start knocking off the easier stuff first.
Make sure your gas cap is tight.
Change your plugs, especially if you think they may be original. I use the Autolite irridium, XP 985. I buy it from Advanced Auto, and not Amazon. Amazon has a lot of fakes, mishandled items, and no quality assurance.
When your Jeep is on, put your hand over the exhaust pipe to ensure there is good pressure. This will eliminate, or confirm, if you have a clogged cat.
Oil change...this is a brutal question. No matter what anyone says, the next poster will say the previous poster doesn't know what they are talking about, or they are wasting money...etc etc etc.
Personally, I wait for Advanced Auto to have a sale, combined with a $5 speed perks, I always use a high mileage full synthetic, such as Castrol or Pennzoil, 5w-30 and get a 5 liter jug for like $20-$22. Sometimes you get a free filter, like a Boss Purolater.
I did check and the gas cap is tight. I'll check the exhaust, good idea! I was considering those plugs after reading a post from Chris, any thoughts regarding coil pacs, or should I change plugs and run it if the problem goes away and not worry about the coils? (That's so unlike me!) Thanx again
I would hold off on doing the coils and just focus on the plugs. Also, you could clean the crankshaft and camshaft position sensors to make sure their connections are good.
I think so. I was breezing through my Chiltons service manual & there is a procedure. I'll try that after I change plugs.
First, I'd toss that Chilton's manual into the trash. It is too thin and covers too many model years to be entirely accurate on any one of them. There are freely downloadable pdf copies of the official Mopar Factory Service Manual that cover just one model year, they are several inches thick and are accurate and complete.
A random misfire can also be caused by a bad crankshaft position sensor (aka CPS). Mounted on the bell housing where the transmission bolts to the engine, it sits next to the flywheel that has timing notches cut into it and generates the master timing signal used by the computer to generate the spark. When that CPS is bad, it can fool the computer into believing the engine is misfiring. If you decide to change it, go for a Mopar and avoid using the cheap store brand sensors sold by stores like Autozone. Store brand sensors are notorious for problems. I had 3 bad oil pressure sensors in a row from Autozone one frustrating Sunday.
A random misfire can also be caused by a bad crankshaft position sensor (aka CPS). Mounted on the bell housing where the transmission bolts to the engine, it sits next to the flywheel that has timing notches cut into it and generates the master timing signal used by the computer to generate the spark. When that CPS is bad, it can fool the computer into believing the engine is misfiring. If you decide to change it, go for a Mopar and avoid using the cheap store brand sensors sold by stores like Autozone. Store brand sensors are notorious for problems. I had 3 bad oil pressure sensors in a row from Autozone one frustrating Sunday.
I don't think you caught my tongue-in-cheek comment made after you said "Thanks again Chris".
Sorry, it went right over my head! We celebrated Independence Day in a big way last night!I don't think you caught my tongue-in-cheek comment made after you said "Thanks again Chris".
Hey all, I changed plugs from (PO's) Bosch Platinum 4's to Autolite Irridium XP 985's and the TJ runs great no dash lights etc. Also changed the oil as suggested (planned on it anyway)! Thanks!
Thanks for the update, it's much appreciated! Glad your TJ is back to running the way it should.
Not easily. It generates pulses as notches in the flywheel pass by it and the way it's constructed with an internal magnet it wouldn't be something you could just measure with something like an Ohmmeter.
spiccolli
Member
This instructor does it with a voltmeter. Doesn't look that hard. I don't think a scope would be necessary unless you get any readings out of the range of what he is showing.
I guess, I think most people with the aptitude to conceptualize a hall effect square wave on a slow volt meter by using the average min/max function probably have a scope lying around, just like this instructor. The other 99% just replace the sensor. That dude's also really loud.