Topic: Misfire, rough/high idle

[Tr00b]

My 1997 TJ was running great. Been running premium fuel and its pulling hills better than ever.

However, when I start it up from dead cold, it has high idle, that is rough. It wants to idle around 1500 rpm but it keeps stumbling and sits around 1100 rpm ish.

When taking off it doesn't do so smoothly until it gets above 1500 rpm, I usually get one or two hard misfires where I can definitely feel it. The idling problem seems to remain on and off for the first 5 minutes of the drive but the misfire goes away quickly. Its a semi-intermittent problem, its almost sure to mess up either with weird idle or misfires but doens't do it every time and usually if its only been sitting for a few hours, its fine.

Known problems:

Power steering pressure transducer is bad. Throwing CEL. Been like this for 6 months.
Leak after the cat
Leak (small) between mani and downpipe.
Motor noise when cold (sounds like lifter tick/piston slap, but not severe)


Generally this is a pretty good running Jeep...
Ignition system totally replaced (except coil), fuel pump, TPS replaced 15k ago
IAT sensor regularly cleaned (gets fouled by valvecover vent oil)
Throttle body cleaned 10k ago
O2 sensors 10k ago
Air filter replaced more often than should


Any input where to start looking on this would be nice... I poked around for an hour and found nothing... Being I am running good fuel, daily driving it I'm  stumped.

[sharpxmen]

leaking injector or something related to ignition

[Tr00b]

The misfiring problem has gone away, I am chalking it up to bad fuel, or perhaps 93 is too high? Normally if its a bad coil, it runs worse when its warm. That was not the case.

How do the later 2.5's advance the ignition timing?

Can you convert them to coil packs?

[sharpxmen]

the timing is based on crank sensor input and engine parameters (rpm, MAP and with modifiers from IAT and coolant Temp). You can't convert to coil packs as you'd need 4 coil command wires (or 2 at least if you go with waste spark), unfortunately you only have 1 wire.

[Tr00b]

Is the coolant temp guage the same for the dash as it is for the ecu? Ie, dash could work but ecm not reading?

I imagine its time to clean IAT again too. I do it every oil change and it needs it every time. Due for a change right now.

Is the crank position sensor accessible from the outside of the engine? I've never seen it.