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2000 XJ Sport - Trying to diagnose intermittent sputtering


NAXJA Forum User
Hi all

Going to share as much info as possible in case something jumps out.

New XJ owner, bought 4 weeks ago. Owner said he had no issues with engine, only the body. I believe him as he let me drive it up and down the highway and around town. Seemed to run great. Had it for two weeks and then decided to get to work to replace the passenger floor pan & seat mount. I disconnected the battery, and the grounded wire under the passenger seat. Got a new floor pan in there, and connected the ground to the new pan and re-connected my battery. It was going to be a few more days until the seat mount came in.

Went out for a drive to test the noise, and the Jeep began to sputter, hard. Slowed to a 2 mph crawl with my foot on the gas, and I'd get pop sounds under the hood (driver side) the more I pressed on the gas. It never actually stalled out, just sputtered to a point where it was barely running.

Now the strange part -- if I turned the Jeep off, and start it back up (even mere seconds later) we're back to full power and no issues.

This sputtering would happen intermittently, either while driving or just idling.

Took to my mechanic who checked the spark plugs...said they looked pretty gnarly, so replaced all 6. He also checked the fuel pressure with a gauge and said it looked fine. Other than that he was unable to recreate the sputter. Even drove with me for about 15 minutes, didn't happen once.

I had the thought that maybe I didn't tighten my battery connection enough, so I re-secured that and the problem seemed to go away.

Then my passenger seat mount arrives. Again, battery disconnected, ground disconnected to do the work. Weld in new seat mount. Attach ground wire to new seat mount. Re-connect battery.

The problem returns. Now I'm thinking it's the battery, looks pretty old and I find some minor leaking. I put a brand new battery in. Take it to Autozone where they use their diagnostic tool to check battery/charging/starting components. Everything looks great.

Was out of town for a few days, just took it for a test drive for about 15 minutes. No issues at first, but then started sputtering again right as I pulled into the driveway so the problem is still there.

I know this is a lot of info and probably most of it is coincidental. But would love any input on what to check next. Thanks for reading.