xj cherokee 4.0 missfire

[cheezel]

Could you measure the exhaust temp just before cat and just after? Using one of those infra red type thermometers? I would think that there should not be a big temp drop but if there is might confirm cats restricted flow? Just a thought..

[Tuffeb]

had a look again tonight

i started it up let it run for few minutes

the exhasut was super hot before the cat and the cat was super hot

pretty cold behind

so i figured bingo gotta be cat after bit of messing around getting the sucker off the cat looks fine inside. no broken grey shit (not sure what its called)

need to seperate the mufler from the cat see if the muffler has colapsed.

another thing is the exhaust has been getting really hot. last weekend i went out n wheeled it. i thought i had an electrical short there was smoke coming from back of drivers seat


the floor was warm, no shorts at all only does it when running not when ignition is on. the heat from exhaust is melting the plastic lining under the carpet.

another thing to add the note of the engine has slightly changed the last few times i have wheeled it. really thinking the mufler has colapsed inside? rusted out?

going to get a new zorst hapening soon anyhow.

another mate said possibly the crank position sensor is out or stuffed making it run lean?

[Cypher]

too much fuel can overheat the catalyic converter, are you getting any black smoke at the exhaust?

[Tuffeb]

Na none at all that's why I didn't think oxy sensor

My other cherokee had oxy sensors orobłens

Looked like a disel lol

[Tuffeb]

removed the exhaust from cat to tip

its 95 ob1 so dosent have a down stream oxy.

still miss firing. so my theorey of blocked zorst is gone

thinking ill pull some leads off n plugs out have a look check the dizzy

pissing down rain here and shed is full at moment so dont tihnk its gonna happen by saturday

[Tuffeb]

the oxy sensor is pretty filthy

its out of fuel so i cant get it to run on fuel and go disconnect the oxy sensor

but on lpg

it idles bit rough when i unplug the oxy sensor loom from underneath its exactly the same

can someone confrim the lpg gets part of its fuel mixture signal from the oxy sensor ill try n get one from autobarn or repco tomorow

ive got a 96 out back but the sensors are different im sure

is 94 the same?? got a 94 in pieces with no motor at mum n dads gouse cant remember if i left the exhaust in it

[junglejuice]

The 94 and the OBD1 95 will be the same, some of the 96's also use the same OBD1 sensors as well.....