Trouble starting with cool not even cold temps

[mikeandamy]

Hey Guys,
You guys really helped me with my rear diff issue, well now i have a new one that I could use your help with.
Last night we reached about 47 degrees in Boston and this morning the jeep didn't really want to start. she cranks and sounds like shes starting but never "Catches" she will catch when i pump the gas and rev the engine a few times and hold the idle at around 1100 rpm's for about 10 or 15 seconds. this is only first thing in the morning and we don't experience the issue the rest of the day nor did we struggle all summer when the night temps were warmer.

Any thoughts on this problem? :wtf2:

 

[mikeandamy]

Update for this morning, the jeep started right up. the current temp is 50 so I would say it is about the same as the night before. I'd also like to note, we bought the jeep last december and struggled with this same first start of the day issue with it all winter, once the warmer air moved in it started great everyday.
I just can figure out what the connection between between the cool temps and not wanting to start would be. I would understand if it was teens or 20's but 45- 50????

 

[Billwill]

What year and model is your KJ?

 

[sevenhelmet]

Check your air filter, clean your throttle body and check your idle air controller. You're allowing more air to the engine when you pump the gas, which means its not getting enough air at cold temps for some reason.

My money's on the Idle Air Controller (IAC), especially if you have an older Liberty. It either has deposits on it or is "hanging up" at first with a cold engine. You'll have to clean or replace it (a new one costs $50.) If you have any questions about how to do that, I just had mine apart last week.

 

[mikeandamy]

02 limited.

IAC? where is it located and how hard is it to change? I am pretty handy with a hammer. no but really, I have done some repairs..........

 

[sevenhelmet]

The idle air controller (IAC) is on the throttle body. It's easy to change. Remove your airbox and intake piping, and the throttle body will be exposed. You can clean it in place using throttle body cleaner, or you can remove the cables, connections, and bolts, and remove it completely. If you've never cleaned your throttle body before, it probably needs it.

For the IAC, there are two electrical devices on the right-hand (driver's) side of the throttle body, one for the throttle position sensor (centered on the throttle valve) and the IAC itself (slightly off center.) You'll need a Torx bit to remove/install the IAC itself. Just loosen the two torx bolts that hold it on and pull the whole thing out. You should be able to move the plunger without forcing it, and it should be relatively clean of carbon deposits.

 

[mikeandamy]

cleaned the iac and throttle body the other day. no problems since. there wasn't much carbon on it but maybe that was the culprit.

Thanks again everyone for the advice........