Topic: 97 TJ 2.5L with hesitation/rough idle when cold

[Thomas]

Help!  Just got my 97" TJ back from the local Chrysler dealer.  I have a friend that has worked there for thirty years. I told him my Jeep suffers from a bad hesitation/ rough idle at times, where it will almost stall the engine.  At other times, I barely notice it.  Seems to do it when its cold.  He downloaded an update to the computer program today,( all covered under warranty) that was supposed to help.  It didn't!  Throttle body spacer, screamon demon coil, wires, rotor and cap, High octane fuel, upgraded plastic fuel tank, new plugs.  2.5L ( a real dog)  He thought maybe catalytic converter, or fuel rail upgrade. Anybody with any suggestions??  Thanks

[Steve97TJ]

Has anyone ever upgraded there fuel rail before? Is there any aftermarket options for it?  Also does anyone make a cam for the 2.5l and would this do anything at all?

[van]

Oxygen sensor?

Initially (I bought it in 2002 with 81K miles) my 97 would sputter within 10-15 seconds of startup from a cold-ish engine.  Overnight wouldn't do it, but going home from work on a warm day would.  A good quick rev up to 2500 rpm would generally "fix" it, until the next cold-start sequence.  It got worse over time, and about a year later, I finally got a code for (downstream, if I recall) O2 sensor.  Replaced it, problem went away.

[Tall Boy]

didja clean your throttle body out. Those cold air intakes cake the butterfly valve enough to throw the idle off. mine threw a code for it.

[Guardian7]

Did they check your fuel pressure?