Help diagnosing engine trouble.

[Bionic_Scorpion]

Update: Went to Auto Zone and got it scanned. It was giving the code P0305. Anyone know what this code is?

Yesterday I was driving down the interstate doing around 70 - 75 mph when the jeep started skipping and losing power intermittently. Also the check engine light went on and off a few times then stayed off. When I slowed down it stopped but after a few miles it started again. I turned around and headed home but it progressively got worse and then started making a popping sound under the floorboards which I think may have been backfiring. It never acted like it was going to die but it had me worried that it might.

I thought it could have been a little water in the fuel because I put $30 in the tank the day before at a station about 2 miles from my house so today I added some ISO-HEET to the tank hoping it would help.

Took it out today and it started doing the same but after driving for awhile it seemed to get better but the check engine light came on again and this time stayed on.

I tried turning the key 3 times to see a code but it never showed anything.

It's a 2000, 6 cyl with 32RH automatic and over 163,000 miles on it. I've had this jeep for over 3 years and never had any problems with it until yesterday.

Does anyone have any ideas what it could be? Can someplace like Autozone scan for a code to see what's wrong?

Thanks for any help guys.

 

[lowell66dart]

Yes get it scanned at Autozone and take a picture of the codes then research them for cause/fix.

 

[Bionic_Scorpion]

Yes get it scanned at Autozone and take a picture of the codes then research them for cause/fix.

Looks like a misfire on cylinder 5. I'll start with the plugs and go from there.

 

[Unique Username]

Diagnostic scanner will be your best friend. Make sure the electrical system is up to snuff. I had a battery with a bad cell causing me to get codes not related to the issue. New battery solved my problem.

 

[ItchyDong]

This is common. Spark plugs probably aren't a bad idea, but if I had to guess its either an injector issue or even more common, a chaffed wire. Check the harness that runs to the injectors. It routes behind the valve cover and chafes. If the PCM controlled ground chafes and makes contact with a ground, it causes the injector to fire all the time. My guess is when you pull the spark plug it will be soaked with fuel.