• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

'00 4.0L Rough/Low Idle Issue

dumbagain

NAXJA Forum User
Location
ohigho
hi
i was stalling when coming to a stop or at very low speeds right after startup.
had my mechanic clean the throttle body and iac and install new plugs and air filter.
jeep drives fine (although i've noticed a drop in mpg lately).

things are a lot better but it still seems that at times the idle is way below 500rpm and i still stall once and a while.

new engine but most the components and sensors have 200K on them.

do you think maybe just replacing the iac would help?
maybe its worn out or was damaged when cleaning?
new mopar tps installed not too long ago.

what might i look into to help this low, uneven idle?

thanks
 
2000 XJ 4.0L

I will get battery load test in the next couple hours.
What grounds should I look at?

Added info: everything was running fine until I can wear I did not use the jeep and we had some torrential downpours. After those few sleep soggy days is what his condition seem to start. It's been trying hot ever since and the mechanic had addressed the situation.

Seems like I'm getting close to 40-50 Less Miles per fill up.

I could also swear that I see some smoke Outback during High acceleration on the highway
 
2000 XJ 4.0L

I will get battery load test in the next couple hours.
What grounds should I look at?

Added info: everything was running fine until I can wear I did not use the jeep and we had some torrential downpours. After those few sleep soggy days is what his condition seem to start. It's been trying hot ever since and the mechanic had addressed the situation.

Seems like I'm getting close to 40-50 Less Miles per fill up.

I could also swear that I see some smoke Outback during High acceleration on the highway
 
Miles per Gallon calculations are the only measure of fuel efficiency.

Test the OBD sensors, and if necessary replace them with genuine Jeep parts, cheap crappy Chinese clone sensors are worthless.

If the O2 sensors have +125 - 175,000 miles on them, they are well past their normal service life.

Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Copper wires should be copper color, not black or green. Battery terminals and battery wire connectors should bright silver, not dull gray and corroded. Do the same for the grounding wires from the starter to engine block, the ground wires at the coil, and the ground wires from the battery and engine to the Jeep's frame/body. You must remove, wire brush, and clean until shiny the cable/wire ends and whatever they bolt onto.

Jeeps do not tolerate low voltage, bad wire connections, or poor grounds.
 
so there's a possibility of a voltage issue causing the IAC to not operate right or more of a spark issue?
TPS i know was Mopar. O2 sensors, at least 1 of them is brand new, i'll have to check the other.

i'll do some snooping hopefully this weekend. Driving around tonight i still had the same issue almost 250 RPM idle at times!
 
Back
Top