Ticking time bomb

I bought my 00 XJ sport 4.0/aw4 in November of this past year and lately, at idle around 4 or 500, I can hear a ticking but only while sitting inside the jeep. Outside, I hear nothing. Oil level is good. This ticking is driving me nuts!! I don't wanna lose my motor, its weak enough with the 0331 head but I gotta find out what this is, any help is greatly appreciated!

Could be the evap purge valve. Its on the passenger side of the fire wall. Should have a green cap on it. You might be able to hear it if you or close enough. If you put your hand on it you will definitely feel it. Its normal to do that.

However your idle is a bit low. Might want to change the spark plugs and air filter. Do a sea foam treatment and clean the throttle body.

Talyn said:

Could be the evap purge valve. Its on the passenger side of the fire wall. Should have a green cap on it. You might be able to hear it if you or close enough. If you put your hand on it you will definitely feel it. Its normal to do that.

However your idle is a bit low. Might want to change the spark plugs and air filter. Do a sea foam treatment and clean the throttle body.

Click to expand...

Agree, likely the purge solenoid.

Your idle should be 700-750 RPM; check after 20 minutes of driving, transmission (auto) in DRIVE with the Parking Brake and someone's foot on the Service Brake pedal. Don't rely on the IP tach, use an external tach.

I will get on that right away. Its been idling at about that point since I bought it in November. I'll have to wait to get a tach or I might plug in the diagnostic computer at school today. I always thought it idled so nice lol. Another awful problem, I had a dry start yesterday after the jeep sat all night. Now this is the second time this has happened since i bought it. BTW, plugs are brand new, air filter is kinda clean, waiting on a pay check to pick up the power pack from Rusty's offroad to pick up some extra mpg's and a little throttle response, but I'll be building a cowel snorkel at that point. Off topic, but why would i be dry starting so randomly? I have Lucas oil stabilizer in and its a good bit because i have higher miles(160k+). I'm trying to baby her and take care of her but she's making it difficult!!!

What do you mean by "dry start"

Do you mean that it takes an extended amount of cranking when engine is cold before it starts?

If you do, the problem is likely the "check valve" in the fuel pump assembly. In the gas tank. SEARCH

It is a very common failure on your vintage.

As birchlakeXJ said.

If you are talking about OIL--what filter are you running? OCD will bite you in the A** sooner or later.

OP, just so ya know: OCD is Orange Can of Death aka Fram oil filter.

well thats what i am running and I was refering to the oil. Guess I'll be swapping oil filters ASAP. its only done this twice though. And as it turns out, I'm idling at 750 pretty constantly. I was misreading the tach. oops.

Get a Wix or Napa Gold oil filter on your Jeep ASAP. The Fram filters have a cruddy anti-drainback valve in them and it can cause dry starts. Even if you just swap oil filters at this point without changing the oil, you will be ahead of the game. Let us know what happens.

cruiser54 said:

OP, just so ya know: OCD is Orange Can of Death aka Fram oil filter.

Click to expand...

I tell everyone, if you like it, dont use a Fram.

Man that just blows my mind. My dad was raving when I told him that was the cause. He just doesn't believe that the filter would do that. At this point, I believe you guys and whats 10 bucks? If it stops it, awesome! If it doesn't, at least thats one less thing I have to worry about. I've always put fram on my cars and never had a problem till now. Crazy.

Maybe they're OK on Dad's old Ford or whatever. But, with the angle that ours are mounted, a good oil filter is critical. FWIW, Fram used to be a good oil filter back in Dad's day.

Swapped out the Fram for a Purolator and changed my oil to Rotella T heavy duty, then today my power pack from rusty's came so I put the throttle body, intake, and exhaust on tonite. Left out the TB spacer though. Don't really care for it and I don't see how they make a difference if any(aside from elevating your TB). Really woke her up! Score!

Okay, we're all happy for your new found power....... How's your oil pressure and ticking? LOL

oil pressure has always been good. at idle its around the first and second notch and under throttle its around the middle always. No ticking either.

I've a 93' XJ 4.0 and had it for about 4yrs now and best damn rig I've owned and I've owned a few. Back when I was rich instead of famous...I would buy a new rig just cause it needed an oil change...j/k but close.
Always been crazy about keeping up maintenence on all my vehicles, thanks to dad making me a gearhead. But shortly after I purchaced my xj it was winter and I was lazy and paid someplace to change my oil and right after I noticed my oil pressure was about 6lbs lower than before. Still ran at good pressures idle and at rev, but still had me wondering so just for fun I changed the sending unit. No change. After dad told me it was fine I soon forgot about it for the past 4 yrs. I figure if you really care about your rig you have to get your hands dirty and learn all you can about it, so I joined a few months ago and have to say a huge thank you for all the effort you guys give to help us with our questions.
Well a few weeks ago I stumbled across a thread talking about OCD and first thought was...BS...the freaking filter?? So...I got my coveralls on and got my self a K&N gold. I know they cost too much but I figured wth, lets do this and find out. I also like the end nut for saving my knuckles, nice feature. Anyways my boggle is that before I was running about 13-15lbs at idle and 30-35lbs at rev, now: 20-25 & 40-45lbs! Next thought was No Way! Thats a hell of a difference....then I'd like to know why. More restriction=higher pressure? Is this a good thing? Always figured good pressure good...low pressure bad. Especially since I just turned 256k! Jeeps rock! I'm still amazed every day by the 4.0, it has so much torque it can easily break lose the tires after so many miles and really runs smooth still. Any insight is appreciated guys, thanks. And thanks again for helping me keep it on the road. ~Jason