playbass

This morning on the way to work, my XJ started to idle rough after getting up to temp. It was sputtering and shaking worse than I've ever felt it at each stop light. The rpms though were staying relatively constant though at 700-725 at idle. I had good power at higher speeds, even at 75 on the freeway, there was no shaking.

On the way home, after the engine got up to temp, the CEL came on and the rough idling came back. My scangauge II says it is throwing the p0171 code which means that the engine is running lean (Bank 1). Supposedly, the engine is going to be dumping more gas, but I don't smell any, though my mileage did suck today.

When I got home I threw on a new TPS and IAC (happened to have the new parts, just never put them on.) That did not fix it (though the tranny shifts better and it starts better.)

What should be my next steps? From reading this site and others, it's possibly my o2 sensors.

One thing I noticed is that my muffler and cat converter shake really bad when it's idling rough. The cat makes some rattling noises too when it's doing it. It's likely that I need a new cat?

The only other thing I did differently this morning was I hit the engine with some degreaser near the back of the head. I'm planning on replacing my valve cover gasket this weekend so I was trying to get some gunk off the back valve cover bolts. Perhaps I hit the o2 sensor with too much?

Is it safe to drive until I get this figured out?

Also, my scangauge won't clear the code and my CEL stays on all the time. Will it stay on till I fix the problem or should it clear?

Thanks in advance,

playbass

I realize I wrote a novel in the age of soundbites, but anyone have an answer to the driveability question?

Would I be damaging anything by driving it over the next few days with the p0171 code being thrown?

I have a new NTK o2 sensor coming in the mail, that's my next move on addressing the issue.

GAPANDA

check this thread....
https://www.cherokeeforum.com/f2/cod...-still-131971/

looks alot like your issue.

IMHO doubt that you could damage anything further.

Good Luck. Also when you did fix it please post up your final solution. As one that still has open issues I hope to help others the way the forum has helped me.

CCKen

While you are waiting for your new O2S, check the O2S heaters fuse in the PDC.

playbass

thank you for that diagram!

DangerXJ

This Is what it looks like on a 2000

DangerXJ

So my 2000 once up to temperature starts skipping and running really rough between 2200 and 3000 rpm. The check engine light comes on than it will flash the longer you run it. I imagine when it misfires it makes the 02 sensors and everything else compound the problem.

If the jeep cools down and you start it later it will run fine again until brought up to temperature.

I recently replaced the plugs and inspected the ignition coil; the plugs I pulled had about 10k on them and were not fouled not could I find any damage in cool.

I'm having an issue with my DLC and i can not successfully use a scan tool to read the code.

Facts you should know:
Recently did water pump due to leak 2 weeks ago.
Small exhaust leak before the muffler.
Heater core is clogged - has not had heat for awhile.
Head gasket done 1 1/2 years ago. Machined the head. Coolant system replaced entirely at this time (only exception heater core...kick myself...)

Thanks for reading

playbass

You should go to an auto shop and get the codes read. I think there is a way you can pull the codes without a reader on the later model XJs too.

Mine isn't misfiring, only sputtering and idling rough at idle, but it only does it at temp.

DangerXJ

Thank you for your response. Without fixing my DLC problem they won't be able to read the codes as well. I have a thread up just about the issues with the DLC. Hopefully i can find something helpful

playbass

Sorry, I didn't catch that.

I think the exhaust leak could cause it to run lean if it's before the downstream o2 sensor. Other than that, you could try to replace your o2 sensors or wait till you get the DLC fixed so you know what exact codes are being thrown.

playbass

This issue has been resolved.

I replaced the upstream o2 sensor with an oem NTK and the CEL went off and I drove it around for about an hour with no further problems. Gas mileage improved as well and no more rough idle.

Still think my cat and muffler are about to go, may be replacing them soon, hence why I didn't replace the downstream o2 sensor just yet.