Won't idle

As the title says it wont idle. I'm able to start it if I hold down the gas pedal a little and keep it above around 1200 rpm. As soon as I let of the gas it stalls. I used the obd2 scanner and it passed. Whats wrong? Also I smell gas fumes. I really need help on this. Thanks

Need more info...engine size...fuel system...


EFI... Electronic Fuel Injection ?...

Carbureator?...

Check ALL vacum lines...

Engine size

4.0L EFI 99,500 miles 1999 Cherokee Sport Throttle body. I use 91 octane because installed chip and intake but problem started before that. I was able to take the air filter off and it ran fine for the way home(one time just to get home). But now that does not work anymore.

TPS going/gone out maybe... (Throttle Postion Sensor)
Tried that one yet? You can always take em back if that's not it.

Don't forget to read: http://www.automotiveforums.com/vbulletin/showthread.php?t=687635

I thought the TPS would throw a code?

Nothing is certain.

Went to start it today and it held idle. Whats going on??

Try looking at the IAC (IDLE AIR CONTROL) valve on the Throttle Body. This should be located left of the TPS on the TB.
The IAC controls the amount of air allowed to pass the butterfly valve in the TB. When idleing, the butterfly valve is totally closed. The IAC uses a plunger ( if I may call it that) that is computer controlled to regulate how much air is needed at idle. If the IAC fails to open, the engine will starve for air. This is why keeping your foot on the gas gets her to run until you wait a few minutes. Your allowing air to enter using the butterfly valve instead of the computer controlled IAC valve. Take the Air hose off and see for yourself..

The problem sounds like its intermittent and might not throw a code at you.

Did you have the battery dissconnected before this happened ?


Went to start it today and it held idle. Whats going on??

r82148v I will look in the morning.

reekor Yes I disconnected the battery. Someone told me that would reset the computer. So should the idle problem happen again? Or is it fixed now for good?