Libby starts and then dies.

[eliotal]

Hello guys, my libby starts up and turns off quickly. When I step on the gas for a while it stays on. I have changed the fuel filter and spark plugs. I also took the alternator to autozone to have it tested and it passed. The battery is less than a year old. I am frustrated and running low on cash. There are no error codes to tell me what is wrong with it. Please help.

 

[Dmut]

it could be dirty air idle speed motor, in the throttle body. it's easy to clean, takes like 15 minutes and spray of brake or carb cleaner.

 

[valvestem]

Hello guys, my libby starts up and turns off quickly. When I step on the gas for a while it stays on. I have changed the fuel filter and spark plugs. I also took the alternator to autozone to have it tested and it passed. The battery is less than a year old. I am frustrated and running low on cash. There are no error codes to tell me what is wrong with it. Please help.

Is the engine cold or warm/hot when it does on starting? Can you keep it running with the gas pedal?

 

[diyman]

Know may sound stupid, but can You feel exhaust gasses flowing from the tail pipe while engine's still running?
In case just find someone willing to lend You a hand and start the engine while You're testing the exhaust...

 

[new jeep owner]

Know may sound stupid, but can You feel exhaust gasses flowing from the tail pipe while engine's still running?
In case just find someone willing to lend You a hand and start the engine while You're testing the exhaust...

your thinking a plugged catalytic converter ?

 

[diyman]

Well, said a bit bluntly.... it could be

Hey, but as all know here, I'm no guru. Hope Dmut is right and it's just a stupid TPS, or fuel pump :shrug:

Anyway, as a general rule of thumb, check out the usual things, like air filter, battery voltage, fuses, relays,
anti-theft... Keep us informed!

 

[Dmut]

not TPS but idle air speed motor, it's different.
there http://www.elcats.ru/chrysler/ImageHandler.ashx?catid=I03&grpid=14&sgrpid=0000610
number (5) is air idle speed motor.

 

[diyman]

Yes Dmut, I realized I had made a mistake after hitting the Submit Reply button....:sorry:

I was hoping to get away with it..... :happy175:

 

[Dmut]

no problem, I just realized that it could be TPS too :waytogo:

 

[belvedere]

There are some good suggestions mentioned. To me, step #1: check fuel pressure.

 

[eliotal]

Thanx guys I will clean the sensor. I will have someone help me check the exhaust later on.

 

[tjkj2002]

Sounds like a sentry key issue,if you have the thick gray key or the keyfob/key all in one you have the OE alarm.If so try another key.Could also be a battery issue,just because it's only a year old does not mean it's any good and yes some batteries test good but are actually bad and the PCM in a KJ is very picky about voltage.


Oh and by the way autozone,advance auto,and all other parts stores can not properly test the alternator in a KJ due to the voltage regulator being in the PCM.You need the DRBIII(or starscan for '06+) to properly test the alternator in a KJ.

 

[valvestem]

I suggest that it is carbon buildup in the throttle intake body. Very little air is needed at idle/first start, the carbon buildup stops the air from getting through. Simple solution, old toothbrush & carb cleaner. Been there done that, seen it happen, seen the solution work. Worth a try and it's easy.
Unless you have been using tainted gasoline, there is no reason to believe the cat(s) are plugged. Battery voltage is easily checked with a voltmeter, or load tester.

 

[tjkj2002]

I suggest that it is carbon buildup in the throttle intake body. Very little air is needed at idle/first start, the carbon buildup stops the air from getting through. Simple solution, old toothbrush & carb cleaner. Been there done that, seen it happen, seen the solution work. Worth a try and it's easy.
Unless you have been using tainted gasoline, there is no reason to believe the cat(s) are plugged. Battery voltage is easily checked with a voltmeter, or load tester.

Do not use carb cleaner,use throttle body cleaner.

 

[eliotal]

Yeah about two weeks ago I had cleaned the throttle body with throttle cleaner and also cleaned the idle sensor as well and when I checked last night it was a little dirty again. A mechanic told me that one of the hoses that connect to the intake hose was kinked and might be the reason it was acting that way. I checked the exhaust and seemed fine just very grimmy. I will drive it around today and see how it all works out. If it doesn't work I will test the fuel pressure later today.

 

[eliotal]

Still the same

I changed the idle sensor, just in case it was messed up. I also had my friend stick his hands on the exhaust and he said he felt air moving around in there. I tested the battery it was at 12.5 amps. After everything It still is acting the same. The car only does this when it is cold and yes it does stay on when I step on the gas. after a while of stepping on the gas the car stays on and drives fine.

 

[Banditsteve]

I changed the idle sensor, just in case it was messed up. I also had my friend stick his hands on the exhaust and he said he felt air moving around in there. I tested the battery it was at 12.5 amps. After everything It still is acting the same. The car only does this when it is cold and yes it does stay on when I step on the gas. after a while of stepping on the gas the car stays on and drives fine.

Just chucking ideas about. Have you checked that all the vacuum hoses are on. When a vehicle is cold it needs a richer mixture (Choke) which is all taken care of by fuel injection system nowadays, but if there is a vacuum hose off it may not be getting quite enough fuel to keep it going when cold but there might be just enough even with a vacuum hose off when its hot? Just a thought. :shrug:

 

[LibertyTC]

Spark Plugs- replace them every 20k miles and check gaps.
PCV valve, clean, or replace, it should rattle when shaken.
IAC info with photos: http://www.jeepkj.com/forum/showthread.php?t=47972
With ethanol mixed fuels, it absorbs water especially in cooler temps. Use a Marine grade "ethanol" fuel staybilizer and an injector cleaner after the fuel staybilzer, to clean injectors. I use Chevron Techron 3 times per year on highway runs to keep the kj clean and do the throttle body intake every 30k miles or with spark plugs and IAC/TPS cleaning.

 

[diyman]

I changed the idle sensor, just in case it was messed up. I also had my friend stick his hands on the exhaust and he said he felt air moving around in there. I tested the battery it was at 12.5 amps. After everything It still is acting the same. The car only does this when it is cold and yes it does stay on when I step on the gas. after a while of stepping on the gas the car stays on and drives fine.

Wait, I know I'm just guessing but.... Do You mean You have an 'hard-start' condition?

You may want to check the ECT sensor ( coolant temperature ) .... Just my 0.02.

 

[eliotal]

I am starting to think that the sentry key might be the problem. I replaced the coolant temp sensor a few months ago for a different reason. My friend checked all the vacuum hoses and told me about the kinked tube but when replaced it made no difference. I'll be looking into the sentry key. I was only given one key when I bought it.