slobra

hi all!

i have a 98 xj, recently its started missfiring. i have changed coil,wires,pick up coil,crank sensor,cap,rotor,swapped rail and injectors and pulled TB off and cleaned all sensors. this is really starting to stump me!

the miss is very noticeable at idle. when i drive it, it seems to go away... anyone had this problem on here before?

any advice would be great!!!!!!

thanks

Bustedback

No mention of replacing the spark plugs, just throwing a bunch of parts at it.

slobra

yea im sorry..i forgot to mention i put the champion copper gapped at .035

Oconee Off-Road

Are you getting any codes from the miss fire. Also did anything change after changing the crank sensor. I Replaced one recently in the shop and was bad out of the box.

slobra

no codes at all.... and yea it took me 3 sensors to get a good one..first 2 were bad out of the box!! it seems to run a little better now but still has the miss....it blowing my mind and wallet lol... going to run a compression check on it today, ill post results

scottmphoto

I see that you replaced the rail and injectors. Did you test your fuel pressure? Possibly a dirty fuel filter or weak/bad fuel pump. How about testing your ignition system to see if you have good spark? Did you clean all of your grounds? Sometimes it is the smallest things that'll throw a monkey wrench into your plans. It's always best to diagnose the problem before throwing parts at it.

belvedere

My '98 had a misfire on #1, and it ended up being the valve springs. However, it consistently gave a code for Cyl 1 Misfire. Yours having a bad misfire, yet no codes, is strange. Like the poster above said, check fuel pressure, and also check for vacuum leaks.

cjfrigo

Also check the injector harness for an open circuit was the cause of my misfire for months . Wire on mine had rubbed the intake and grounded my injector.