he has 99 Cherokee and it has started to sputter while he drives it. i have a code reader so we ran it and it came up with a misfire in cylinder 1 and came up as the catalyst monitor.

any ideas? somebody told his wife that it would cost 1200 to fix but didnt say what it was.

 

check your upstream o2 sensor for switching; catalyst codes (p0420, i assume) are usually either an o2 problem, or your cat is fried. chances are, if someone said $1200, they are recommending the cat and both o2s, which may or may not be necessary. check your o2 sensors first.

 

What are the exact code #'s?

 

the only code that came up is p0301 which was the misfire in 1. it had an indicator that meant catalyst monitor

 

BS. lol.

As someone else said, Cat or O2 sensors are pretty likely.

 

that would cause the misfire?

 

Yes, P0301 is a cylinder 1 misfire, but there are no other "indicators" for catalyst problems other than different codes......please confirm what you mean here.

If this were my vehicle, I would chase the misfire first and then see where you are at.

For misfires, you absolutely must first suspect tuneup hardware. That includes fresh Champion copper plugs gapped to .035, fresh plug wires, new distributor cap and rotor. Simple stuff first. ALWAYS>

 

Combustion doesn't occur (misfire) due to lack of spark, fuel, air or a combo. O2s and cats don't cause misfires but misfires can ruin cats. Like tj says, do a tune-up.

 

+1 on the tune up. Could simply be a bad plug wire or a gap of 'zero' on the park plugs

 

Well, O2 sensors can cause a missfire if the AFratio is set off because of the missread in the sensor causing the cylinder to run lean and a spark plug is weak, can do it. But that is rare in most cases you want to start with the cheapest solutions first unless you have the fix known. Check the spark plug for fowling and go from there.

 

was it hesitating and sputtering and sorta backfireing? if so i had/have same prob.

-new plugs wires
-new cap rotor
-new IAC
-new TPS
-blew out gas lines/ cleaned pump assambly

after all that prob went away or a while, but will randomly act up again... it seems to only happen at lower/partial throttle, so the IAC or TPS might still be to blame...

 

VT, if it is random it just might be the Throttle body or in it, a path clogged where the IAC is, not sure if you cleaned it out or not. Maybe check for a very small vacuum leak with a can of crab cleaner.

 

let see, i took the TB totally off and cleaned the hell out of it with carb cleaner... there was a gasket on the old IAC and the new one i installed didnt have one. i know i can put some silicone on it to make that seal, but havent yet... also, is there an adjustment on the IAC or TPS i dont know about. as for the vac leak, i think there is a small one somewhere... the airflow changes from the floor the the dash under acceleration... but once again, i havent checked w/ the carb clarner yet...

 

x2 (3?) Check these. Even try swapping the wire if it test to conduct, wires can be intermittent. I had my wire become intermittent on one of my cars. It was a pain in the butt, they always seem to go out when I need to hit the gas.

 

I did not know that.....it just seems like if the O2 were at fault, that multiple cylinders would indicate a misfire, not just cylinder #1, no?