Need Help Diagnosing Hard Start, Sputtering, Hesitating 2004 Grand Cherokee 4.7L HO

[bdzb1234]

It usually takes 2 or 3 tries to turn over. Sometimes it will start, sputter for a few seconds, and die.

Check Engine light goes on sometimes then goes away and then comes back later. I went to Autozone to have it checked and they didn't tell me the exact code but said it was an O2 sensor. I have never heard of an O2 sensor causing this before.

Also, it seems to lack power/ hesitate sometimes when I hit the gas pedal (The 4.7L HO had a lot of balls before this started happening ).

I ran some fuel system cleaner through and it made no difference at all.

I am thinking it's a fuel issue, but other than hesitation and taking extra cranks to turn over, it doesn't die out or anything like that.

I am going to Autozone tomorrow to get the exact code causing the check engine light.

Does anyone have any ideas on what could be causing this?

[jeep2002]

Yes an 02 sensor will cause hesitation and severe driveability problems

[theFREAKnasty82]

the hard starting issues could be fuel pressure/volume related. Your fuel pressure should be somewhere around 49 PSI

[bdzb1234]

Ok, I got the codes today:

P0300
P0301
P0302
P0304

Apparently these indicate misfires but they are different than the first code I got when I first posted this which was an O2 sensor code (not sure which one).

I had to replace the battery last weekend so the O2 code is gone. I have driven about 300 miles this week and now only have these codes.

Could the O2 sensor cause these misfires somehow or is it more likely spark plugs? My vehicle has 117,000 miles on it.

[mopar96]

Multiple misfires, yikes.....change all plugs and check coils to see if cracked or damaged and replace as needed...

[bdzb1234]

Originally Posted by mopar96

Multiple misfires, yikes.....change all plugs and check coils to see if cracked or damaged and replace as needed...

Yeah I'm concerned because I know the 4.7L HO takes unique plugs and I'm scared that the previous owner put the wrong plugs in. I have only had this vehicle for 3 months and it started acting up after about 3 weeks of owning it.

I ordered the plugs online so once they arrive I will change them out and see what happens.

My check engine light is gone today so ????

[msdz]

I had same issue about a week ago. Only had one plug misfiring, I can only imagine what yours must have been running like with multiple misfires. A misfiring plug can cause an O2 sensor code as well. So replacing the plugs can help with the O2 sensor trouble code you did have.
All I have read says to use a copper electrode spark plugs with original specs. I didn't notice this until I bought mine(only had my 99 for a bout 9 months). So far jeep is running good with the platinum plugs I bought.