BlueArmadillo

I bought my XJ a few months ago with no problems other than it needs a tie rod end job. After a few weeks of regular driving, I was going to Carolina Beach on a camping trip when it suddenly started misfiring and had no power. After some research I replaced a coolant temperature sensor, catalytic converter, spark plugs, wires, air filter, o2 sensor, fuel filter, rotor cap and button, all to no avail. It definitely helped out a lot, but I'm still having issues. I'm going to replace my fuel pump next, but has anybody else had similar issues with their 4.0s?

Tyler01

I'm in the same boat. My jeep has bad stuttering problems and backfires and feels like there's not much power either

bloddy mud

Don't forget the fuel filter while your at the fuel pump. What kind of fuel pressure you running at the rail

thomas0202

My 95 will misfire on me occasionally when Im sitting at a stoplight or something. If I rev it up abit it goes away mostly. It was alot worse before I fixed my cracked exhaust manifold and did a cleaning on my injectors and ran some seafoam through them while applying power. Helped misfiring quite well but it honestly could have been anything. Id say your replacing parts that could cause a misfire. Id also check the TPS cause I've read that it can cause power loss if it wont allow throttle position to be shown correctly. Im sure others will chime in eventually as well.

BlueArmadillo

I dont think I have a cracked exhaust manifold, but ill take another look tomorrow. I havent ran seafoam through it yet, Ill probably do that once I go home for Christmas at my parents place.

thomas0202

I didnt think I did either but I did and fixing it did brought back some lost power. Changed the O2 at the same time so that may have contributed some.

BlueArmadillo

Whats the best way to check for hairline cracks?

thomas0202

I dont really know that answer but if its like mine it was cracked right where the two pipes merge at the collector right where it bolts to the downpipe. Look there and try to shine a light everywhere you can get it. If there is a crack there it should be easily noticable.

cruiser54

Need to check fuel pressure with a gauge before proceeding.

Fuel starvation causes a "lean backfire".

BlueArmadillo

Definitely will do that ASAP as well

Tyler01

I figured why my 89 Cherokee started backfire and had no power and stuttering. One of my plug ins on the injector didn't have a good connection causing me to get fuel to 5 of my cyclinder. After fixing it everything ran good as new so possibly check that cuz simply plug end caused all that on me.

BlueArmadillo

I went all winter without having any major issues with my motor, until the first hot day of the year rolls around, and it starts again. The other parts I've replaced since my initial post have been the fuel pump, and battery wiring. I'm thinking i might wrap the injectors with exhaust wrap, to insulate them from the heat.

Any thoughts?

BlueArmadillo

Replaced the fuel pump, and filter, cleaned the injectors and ports, and heat wrapped them along with the rail, and I haven't had any issues yet. I'm hoping that this will fix the problem.

cruiser54

Wrapped with what?

BlueArmadillo

Heat shield tape