ok so i have a 2000 disco 2 100k started running a little rough. it has a small exhaust leak and then all of the sudden check engine light starts flashing and i hear a very random knocking doesn't sound like ticking/lifter or rod or piston almost like the exhaust is knocking and no power very rough idle. when its cold it runs good (well a ton better). these are the codes coming up p0306,p0154,p0130 and p0139 the check engine light was already on. i was told an exhaust leak could not cause that bad of a running condition but could cause the o2 codes but o2 sensors should not make it run that bad????? anyone have any experience with this?

 

I would check all wiring going to the O2 sensors for cracked, broken, pinched and burned wires. Wires could be burned or melted by exhaust leak. check sparkplug , sparkplug wire for number 6 cylinder if number 6 is really misfiring it sends unburnt fuel in exhaust where it burns and could make flames come out of the exhaust leak (not a likely possibility) If you want to know why it runs better cold look up: ' open loop and closed loop operation of fuel injection' . There are other possibilities but if Disco's cars computer is not getting signals form O2 sensors in bank 1 and 2 it will run bad. Got to go my boss walked in (I am at work )

 

have someone hold a rag over the tailpipe and you should be able to hear the leak under the truck.
it wouldn't hurt to swap the number 6 plug and wire with another to see if the problem follows.
do you know how long the codes have been their, have you ever cleared them before?

 

OK thankyou. Will look as soon as I get home from work.

 

They were just reset. Those were the first codes to pop up. I'll put the reader on it after work and let you know if more are there. Thanks.

 

ok so now there are more codes p0130,p0155,p0161,p0135,p0300 im going to do exhaust gaskets this weekend and probably o2 sensors unl;ess people dont recomend doing that?? or maybe something else. im going to check o2 wires and #6 plug and wire and check to hear how bad the exhaust leak is. if you can think of anything else i can check i would appreciate the info. thanks again james and drow