Topic: rlly bad miss

[lanulos89]

so my jeep has a horrible miss now started last night, doesnt even idle good, if my tach worked it prob goes from 1k to like 500 and back up...  thinking maybe fuel injectors,  also it struggles to get over 40mph, it kinda sucks taking back road everywhee i go  please help

[Jeffy]

First thing is to check for CEL codes.  I would guess TPS, CPS or AIS.  My guess is the engine wants to stall but then catches itself which causes the idle to jump.

[YJmechanic]

jeffy is right on this one hopefully just a sensor but you have to figure out which cyl is mis firing first.  have someone with a scanner check it then go to that cyl and swicth the plug for a known good one from another cyl and see which one misfires then.  if the same keep on digging or if differant you have the answer.  it can be fuel spark ignition or deaper like cam lifter valve.  run a compression test and make sure the valves are sealing and check against the other cyls as comparison.  has it been over heated??   over heated valves or cracked head will do it too.  any lifter noise that wasn't there before?? 

[lanulos89]

its been doing this for months just hasnt been bad and i couldnt figure out the problem.  now its bad.  doesnt over heat, its starting to need a head gasket, i conifirmed that with compression test,  done a tune up twice, plugs wires cap rotor.  replaced coil.  morow gonna take out fuel filter an blow thru it, and maybe remove injectors and see wuts up in there, maybe try and clean em out that way,  or plugg cyclinder wires.  isnt storing anu codes which is pissing me off.  sensors, i guess but there is no way to test them rlly so thats blind guessing too

[Jesse-James]

  sensors, i guess but there is no way to test them rlly

Sure there is, we just went through testing the TPS on here with OldJeep's rig.

[YJmechanic]

you have to figure out which cyl is misfiring  first.  if it is the same one every time then the sensors are fine.  also if it is only one your filter is fine too.  if you suspect an injector then switch two of them and then see which misfires.  then only good way to diag this is to monitor the cyl  while running.  don't do the head untill you figure it out.  bad compression may be from a bent valve and not the gasket which can cause a nasty misfire too.  if the valve gets slightly bent then it will not open correctly or fully and there is our misfire.  either way you have to norrow it down to one cyl first.

[lanulos89]

k well i didnt get to lok at it at all today, but now its idling high and exhaust stinks bad

[aw12345]

If the exhaust stinks bad its running rich.

Art

[lanulos89]

oh meant to update, fixed the high idle, TPS,  and yea it is running rich finally got the obd I scanner hooked upto it, now its just figuring out why its running rich, sugetsions, i also have a hard start condition every once in a while.  im leaning toward the CPS

[neale_rs]

The computer controls how rich or lean it runs at the computer gets its information about this from the O2 sensor so I would suspect that.  The hard starts could be due to the CPS.

[omnisi]

I had idle probs...revved up and down.  Used electronics cleaner to clean my TPS, CPS, IAC, and upper O2 sensor....prob solved, runs perfect...

[lanulos89]

o2 sensor is new forgot to mention that, auto zone has a burn mark in there counter but its new.