Jeep idling like crap

[jdmc1753]

2003 TJ 5 Speed Manual. After I get going and warm up, my Jeep decides she’s gonna idle like crap. If I go into neutral it will idle down to 2-300 and then eventually die after a couple seconds, if I gas it and keep it above 1,500 rpm it’ll stay running, also when I shift it bogs down til I hit 1500 again. Replaced the TPS, all 4 O2 sensors(yes NGK), and plugs. No codes either, any suggestions would be much appreciated. I’m gonna take apart and clean the throttle body and IAC tomorrow morning

 

[AjRagno]

Cleaning the IAC is a good step to take here but it’s not necessary to remove the throttle body and probably best not to remove it as it’s easy to over-tighten the bolts. Just get the engine warmed up, remove the air intake and spray throttle body cleaner into the IAC opening.

 

[Rooscooter]

Cleaning the IAC is a good step to take here but it’s not necessary to remove the throttle body and probably best not to remove it as it’s easy to over-tighten the bolts. Just get the engine warmed up, remove the air intake and spray throttle body cleaner into the IAC opening.

+1

 

[Jerry Bransford]

Cleaning the IAC is a good step to take here but it’s not necessary to remove the throttle body and probably best not to remove it as it’s easy to over-tighten the bolts. Just get the engine warmed up, remove the air intake and spray throttle body cleaner into the IAC opening.

X2 but it's important if you are cleaning the IAC that you spray the cleaner into the throttle body only at idle rpms. Only at idle rpms will the IAC suck the cleaner in through itself. At higher rpms the cleaner will completely bypass the IAC. The engine will stall when the IAC is flooded with the cleaner but that's normal and ok. Just restart the engine and do it again until at least 1/3 of the can of cleaner has passed through the IAC.

 

[jdmc1753]

Cleaning the IAC is a good step to take here but it’s not necessary to remove the throttle body and probably best not to remove it as it’s easy to over-tighten the bolts. Just get the engine warmed up, remove the air intake and spray throttle body cleaner into the IAC opening.

Thanks for the input, did like you said. Took 10 minutes and it’s already idling way better, we’ll find out tomorrow when I drive to work.

 

[SaharaKev]

X2 but it's important if you are cleaning the IAC that you spray the cleaner into the throttle body only at idle rpms. Only at idle rpms will the IAC suck the cleaner in through itself. At higher rpms the cleaner will completely bypass the IAC. The engine will stall when the IAC is flooded with the cleaner but that's normal and ok. Just restart the engine and do it again until at least 1/3 of the can of cleaner has passed through the IAC.

Could this process be done as part of maintenance or is it only beneficial if there is a problem with idle?

 

[AjRagno]

Could this process be done as part of maintenance or is it only beneficial if there is a problem with idle?

As long as everything is working, I wouldn’t worry about it. You can however remove the air intake tube and see if the throttle body butterfly has carbon buildup. Is yes, the IAC likely has some buildup as well.

 

[Chris]

Let us know if that fixed your issue

 

[TJ2]

2003 TJ 5 Speed Manual. After I get going and warm up, my Jeep decides she’s gonna idle like crap. If I go into neutral it will idle down to 2-300 and then eventually die after a couple seconds, if I gas it and keep it above 1,500 rpm it’ll stay running, also when I shift it bogs down til I hit 1500 again. Replaced the TPS, all 4 O2 sensors(yes NGK), and plugs. No codes either, any suggestions would be much appreciated. I’m gonna take apart and clean the throttle body and IAC tomorrow morning

You have to replace the CPS.

 

[jdmc1753]

Let us know if that fixed your issue

It seems to have fixed it, I only drove it about 20 miles yesterday, but I stopped and started it back up. No issues with the idle after warmup, so I believe it did

 

[Chris]

It seems to have fixed it, I only drove it about 20 miles yesterday, but I stopped and started it back up. No issues with the idle after warmup, so I believe it did

That’s great news!