2000 cherokee chk eng light

[markg]

my son broke down last nite in his 2000 cherokee.
it died and wouldnt start as he was driving.
we pushed it into a lot and found that a vacuum line had popped off on the intake just below the throttle body.
i found it on the ground right where it originally died and it started once put on again but you had to keep the rpms way up.
everytime it tried to start again it acted like the timing was way off and popped and backfired but eventually started as long as you kepth the rpms way up.if you tried to let it idle it died right away.sometimes if it backfired it would pop thart vac elbow off again.
the muffler looked destroyed and we thought it was blocked inside so we sawzalled it off and i think that was the problem.
it runs and idles but idles poorly.
we thought maybe the cat was cloged or broken inside so he decided to cut that too as he is going to just get a whole new system put on.
it runs and wont stall but seems rough and the chk eng light is flashing like it sees a major problem.
we cut this all pretty far after the only oxygen sensor.
do you think the chk eng light is blinking because it senses no cat?
he is getting a new exhaust put on today and im just wondering if i need to do more work to fix the problem.

 

[boncrshr]

You are going to need to see what the actual code is to start with. You can get an OBDII code scanner for cheap and sync it with your phone. Once you have the code, forum users can point you in the right direction.

 

[markg]

well theres no cat or exhaust and it didnt blink before this.he will get a new exhaust on today and then well check codes afterwards if they are still there.
before this the light came on about a month ago with a small evap leak which we were trying to track down.


thank you

 

[Unclewolverine]

You need to get a code reader on it but a blinking light means a cylinder misfire. Kinda sounds like you have a valve train issue. How many miles?

 

[XJI6191]

Thanks, I was puzzled by the blinking light as in (admittedly) experience of such things they either come on & stay on (sometimes cured by a number of key cycles) or are intermittent.

How does a misfire fit in with the vacuum line coming off?

 

[boncrshr]

How does a misfire fit in with the vacuum line coming off?

If you experience a backfire it will blow that fitting off. Happened to me when my coil rail went bad and I was having backfires.

 

[Unclewolverine]

Yeah, back fires can blow any loose vacuum lines off in a hurry. Being a 2000 it could very well be as simple as a bad coilpack, or as complicated as a whole host of other electrical problems. Getting the codes is the first step here. Compression test may be the second step. Also does this jeep have the pre cats? They could be clogged as well.

 

[lawsoncl]

Before you dump money into a new exhaust, figure out why it's backfiring. You might have a more serious problem going on.

 

[90xj06]

if the crank sensor wiring is melted and shorting to the exhaust it will kill the engine and that might be enough to bounce the wire off the exhaust and try and keep running and could cause a backfire. when its popping and backfiring is the rpm gauge instantly dropping to 0 and back up?

 

[markg]

thanks...it had a bad coil pack.we put a new exhaust and a known good coil rail on it and its fine.

 

[jeep ride]

thanks...it had a bad coil pack.we put a new exhaust and a known good coil rail on it and its fine.

Good news thanks for the update.

 

[XJI6191]

Always good to learn that a problem's solved & how it was achieved.

All too often often threads just go quiet & we're all left wondering what happened.