multiple cyclinder misfire after installing lift

not sure what forum this should be in...
i just installed a FT 6" LA kit on my '00 XJ this last week and upon completion, started it up and it runs like crap. the exhaust pipe between the cat and muffler started to glow red after about 15min. of runtime. i took the cat out and now there is just a straight pipe. the vibration has gone down a lot, but something is still wrong. the engine seems to run worse as it warms up. i took electrical connections off the injectors one by one at idle to see it i could find wich ones may be the culprit. the #1 and 6 injectors had no effect on idle speed. #3 may also be bad but still not sure. i also noticed a small crack by one of the coils on the rail, which wasn't there when i put new plugs in around 10K ago. it's a 4.0L w/ 70k on it. any advice would be great.

i am also wondering as to where the best place to buy oem ignition parts for it would be, as opposed to going to the dealership.

Maybe your cat is clogged?

Did you adjust your fuel mixture and timing to compensate for the change in altitude gained by the lift?



j/p I have no tech to offer....today!

if your cat is glowing after 15 minutes and you have a really bad misfire all the sudden chances are your leaning out really bad i'd be careful with that. are you getting any codes from it? might wanna look over what you could of disrupted with the lift.

Have you checked for spark in cylinders #1 and #6? If they're not firing then the unburned fuel will roast your cat, as you have figured out.

did you possibly knock off or break the O2 sensor when putting on the lift?

cant adjust fuel mixture on a 2000 w/o a pc. didnt break off o2 sensors. already replaced cat w/ straight pipe.

i did some reading. on '00 and '01 the distributorless ignition system uses a "coil rail" which consists of 3 coils, plug wires and boots all in one waterproof,non servicable item. each coil is paired with two cyclinders and sends spark to both every time whether fuel is there or not. i also found out that 1 and 6 share the same coil,well there is a small crack on the rail next to the first coil.

so i ordered a new rail and should get it today, will post if it worked or not.
it was only $125 from the dealership. good deal ithought for spark plug wires and 3 coils.

forgot to say that no check engine light ever came on...

jeepkid2000 said:

forgot to say that no check engine light ever came on...

Click to expand...

Yeah... my other ride ('03 PT Cruiser) has had a bad misfire for a few weeks now (originally thought I had a bad tank of fuel or such, so I've been "waiting it out").... and FINALLY the Check-engine light came on after about two weeks....

It seems a bit slow.

My problem was nuttin' but spark plugs. Which, come to think of it, the Jeep should probably be treated to, too!

Den

yeah plugs are a good thing to check, i replaced mine about 15k ago.

Make sure you didnt kink any fuel lines during the lift, and or other lines that might supply air or emmission controls.

i replaced the coil rail/ spark plug wire unit, and it sounds brand new. took a minute to idle right again, im guessing because the cpu had to get aquainted w/ the new part or all the extra fuel in the two cyclinders
it works again.
now, time for an alignment and some 34's

vacume lines i did the same thing it kinda makes it sound like u have a big cam at idol but loss of power check all vacume lines and u will fix ur problem

jeepkid2000 said:

i replaced the coil rail/ spark plug wire unit, and it sounds brand new.

Click to expand...

are you blind!?!

it wasn't a vacuum line, one of the three coils on the coil rail had failed.
so no spark to those two cylinders.

learn to read. by the way, vacuum is spelled v-a-c-u-u-m , not vacume.