PDA

View Full Version : Tj 4.0 Hesitation And Backfire


tj4xfun
03-20-2006, 07:53 PM
Since I Bought My 98 Tj 4.0 Auto She Acts Strange When Shes Cold. She Starts And Will Drive Good Until The Coolant Temp Reaches About 120. Then She Hesitates, Back Fires, And Sputters. If I Stomp Her To The Floor For A Couple Seconds She Runs Great From Then On Until I Turn Her Off.

When I Restart Her, She Will Run Good For About Thirty Seconds Then Act Up Again. A Stomp To The Floor Clears It Up Again. This Isn't All That Bad On The Street But On The Trail I Cant Stomp It To The Floor.

If She Idles For A Couple Minutes, She Runs Great Without The Problem. I Suspect It Has To Do With The Fuel Injection Going From Open Loop To Closed Loop But I Don't Have Easy Access To A Scanner. I Don't Have A Check Engine Light On And I Don't Have Any Smells Out The Exhaust. I Suspect The Front O2 Sensor Is Lazy And Delaying The Change Over From Open To Closed Loop. I Believe These Obd2 Fuel Systems Run On A 2 Minute Cycle When They're Started Until They Reach Normal Operating Temp.

Anyone Ever Experiance This? Any Ideas? Any Suggestions? I Don't Want To Start Throwing Expensive Parts At Her If Not Needed. I'm Gonna Post This On Other Forums, Hopefully I'll Get An Answer.

tj4xfun
03-28-2006, 09:50 AM
I MADE THE FIX. WITH THE HELP OF A FRIEND WE HOOKED IT UP TO A SCANNER. THERE WERE NO CODES AND NOTHING JUMPED OUT AS BEING BAD. THE ONLY THING WE NOTICED WAS THE O2 SENSOR WAS SLUGGISH AS I EXPECTED. THE FIX WAS TO INSTALL A NEW O2 SENSOR. SHE RUNS GREAT. TALK TO YOU SOON.

njbowhntr
03-28-2006, 05:43 PM
Sorry we could not help you. We are glad that you got it fixed and are up and running.