03 KJ stalling, cant figure it out

askoop · **Posted:** Fri Jan 23, 2009 12:22 am

my wifes 03 KJ (3.7, 5 speed) has been stalling. Started about 2 months ago, the first cold day we had. It would stall anywhere below 750 RPMs but only when the engine was hot. It was low on gas, so I filled it up and the problem went away the next day, never had another hiccup until about a week ago.

it has now progressed to stalling no matter what, unless I am really hitting the gas and keeping the RPMs high. I was messing around with some stuff and noticed that some of the vacuum hose connections were cracked, so I pulled off the vacuum hose that connects to the throttle body near the IAC. This seemed to fix the problem, everything runs just fine with that hose off. Engine dies when you put the hose back on.

I am thinking that it may be something blocking the vacuum hose somewhere, its not in the immediate chunk of hose that connects to the throttle body, already checked that. Been driving it a little bit, only as necessary until I get some more time, and today the check engine light came on, and threw code P1494. I assume this is only becasue that vacuum hose is not hooked up. At least I hope so.

Any ideas what may be wrong?. am I on the right track of a plugged vacuum hose somewhere or maybe some type of valve in the vacuum lines isnt opening or is stuck open? Any help would be appreciated!

Jeepjeepster · **Posted:** Fri Jan 23, 2009 12:43 am

Yes, it seems that code would be do to a vacuum leak.

Its sounds like you have something wrong with the idle. It will run ok with the vacuum hose off since it by passes the throttle and lets air right into the engine.

Are you 100% sure there are no other codes? The IAC sensor popped into my head but that should throw a code.. IAC=Idle air control sensor. Its on the throttle body.

How many miles are on the Jeep? Ever change the spark plugs? They should be changed every 30k. Have you checked to see if the throttle body is clean?

Does it seem to run ok at higher rpms? Noticed a loss of power??

Guest · **Posted:** Fri Jan 23, 2009 12:45 am

Yeesh, JeepJeepster...stop beatin me

My fix...

"give it more gas and let the clutch out slower" :lol:

501 · **Posted:** Fri Jan 23, 2009 12:47 am

How old is your battery? Mine would stall unless I kept my foot on the gas. I changed the battery and all is good.

askoop · **Posted:** Fri Jan 23, 2009 1:11 am

hmmmm, battery... its original, but I would think that taking the vacuum hose off wouldnt make a difference if it was the battery... terminals are clean. guess I could take the battery to AZ and have them test it.

KJ has 80K on the clock, I changed the plugs in the summer of 2007, used the stock NGK ones, got em from NAPA. that was 10K miles or less ago

There are no other codes, I checked twice... flashed p1494, then "done"

I sprayed some carb/intake cleaner into the throttle body, but the stupid nozzle on the can broke, so I couldnt get a ton in there. I plan to really get in there and look/clean it, but have been super busy at work lately. might get some time Sunday. I also checked the air filter, it is also free of debris and I can see sunlight through it easily when held up to the sky.

It seems to run OK at higher RPMs, especially when it first started happening, anything over 750 at first, then it had to be over 1000 to keep going.

501 · **Posted:** Fri Jan 23, 2009 1:24 am

I know it sounds crazy but mine would run great when it was cold, I drive for like 10 minutes, stop at a stop sign and it would die. Then every time I'd stop it would not idle so I'd have to keep one foot on the gas and one on the brake. I bought a new battery and haven't had the problem since. Someone told me it had to do with not enough power to the computer.

askoop · **Posted:** Fri Jan 23, 2009 10:51 am

did the battery test as bad?

Not saying you are wrong, because what you describe is exactly what mine is doing. All indications, at least in my head, dont lead to the battery though. I guess the battery is 6 years old now, probably time for a new one soon anyway.

sleeve84028 · **Posted:** Fri Jan 23, 2009 12:17 pm

A bum battery can really do weird things to the KJ. If that computer system isn't happy your KJ isn't happy...

Maximum Carnage · **Posted:** Fri Jan 23, 2009 2:03 pm

Yup, a drained battery sure can do weird things.
Last week it was really come here in MN. We were headed up to the casino and stopped at a liquor store for some refreshments :wink:

and I left the lights on. Well we all know they turn off by themselves. Well when we were leaving about 15 minutes later it wouldn’t start. Had a guy give me a jump and it would not stay idle I have to keep my foot on the gas 1K RPM until the battery got enough juice and then we were ready to go. I checked it when we got back that weekend and the battery checked out fine. I think it just was too cold and leaving the lights on might have just drained it.

tjkj2002 · **Posted:** Fri Jan 23, 2009 8:37 pm

OBDII code P1494 is for the leak detection pump for the EVAP system.That hose you disconnected was for the EVAP system and is used for emission reasons.Start checking all the EVAP hoses by the EVAP canister that is mounted right in front of the gas tank(black box looking thing),probally got a cracked hose back there also.

501 · **Posted:** Fri Jan 23, 2009 8:41 pm

askoop wrote:

did the battery test as bad?

Not saying you are wrong, because what you describe is exactly what mine is doing. All indications, at least in my head, dont lead to the battery though. I guess the battery is 6 years old now, probably time for a new one soon anyway.

Didn't even have it tested. It was the original battery in an 03, so I fugred it needed a new one and replaced it.

askoop · **Posted:** Sun Jan 25, 2009 8:58 pm

you guys are freakin geniuses!

Had the battery tested and the tester at AZ said she was surprised that the KJ was even running the battery tested so low. Got a new battery and installed it, reconnected the vacuum hose I had disconnected, and started right up, no problems, and check engine light off.

Thanks so much guys, you saved me a ton of what would have been wasted time tracking down a problem that didnt exist!

You are all awesome!

501 · **Posted:** Sun Jan 25, 2009 9:54 pm

Glad to hear all is good Askoop!

03 KJ stalling, cant figure it out

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