Ruttenit

I just bought another cherokee with the 4.0 and when it gets warmed up it runs kinda rough from I think its 17or 1800 rpms and below. Anything above that it runs great!!!! Better than my 98 in fact. When going really slow it wheeling if sounds like its going to die but it never has yet.

Any ideas? I am kinda new to the EFI stuff I have always used carbs.

mr.auto

year plz

Ruttenit

1995 sorry

Oh and the guy said that it hasn't been ran for a month or so. I also drove it home from about 2 1/2 to 3 hour drive.

Brett

my 95 was doin the same thing.... cleaned up the injectors and swapped out to some ngk platinums.. I also ran a tank of supreme just for good measure now it purrs like a kitty

Ruttenit

When I pull out all the injectors to clean them do I have to install new rubber O rings? Oh and do I have to bleed the lines or does it do it on its own?
Thanks

projectmayhem

the old o-rings should be fine just look over them for brittling or cracking

Brett

i didnt pull em i went the ghetto route and did the wally world injector cleaner just cuz my buddy works in there tire center and it was free the plugs were just kinda a tune up measure prolly dont have to do that

JeepCoMJ

do not run platinum or any other special metal spark plugs in a 4.0. the high nickel content in the casting of the heads is not compatible with the special metals, which means that platinum etc. plugs won't ground through the head and block as well as the stock plugs do, resulting in poor burn on fuel.


stick with the $2 factory plugs and you'll be happier.



anyways, to the O.P....run premium through it with injector cleaner. your issue is that your fuel system is gummed up from bad/old fuel.

Copytech

ERRR The special metal is only in the center electrode not the whole plug. The plug will ground just fine.

arsxj

Do a compression check for peace of mind. If its bad you can stop throwing parts and money at it. Mine did the same thing and it turned out it has low compression in 3 & 6. Mine even runs smooth sometimes and rough others... There finiky beasts

BTW. If you dont have a compression tester you can rent on from the parts store for around $40 and you get all your money back when you return it. Everyone should do this. Your rigs compression is a good thing to know.