1999 Jeep Wrangler Jeep won't stay running

WDONAT

MEMBER
1999 JEEP WRANGLER
6 CYL
4WD
MANUAL
85,000 MILES

I live in Anchorage, where it's been bitter cold (below zero) for a few weeks now. Yesterday my Jeep started acting up. When I first start it (engine cold) it will not stay running if I take my foot off of the accelerator - at least until the water temp reaches 150 degrees.

In other words, once I start the engine, I have to stay in the car with my foot on the gas until the engine reaches almost operating temp, otherwise it dies and I have to start it again. Once it reaches that magic temp, though, it runs fine.

if somebody could just point me in the right direction for a place to start, that'd be great. Thanks.

1 Reply

IMPALASS

MECHANIC
3,112 POSTS

Hello -

If you would, please go to Auto Zone (AZ) or O'Reilly's (OR) and for FREE they can pull the codes to the car. Most important: Once they check your codes, if they find something and you don't get it fixed and need to get back with us, please make sure you tell us exactly what the code was, number and all. Example, if the code was E0568 O2 Sensor bad. Then make sure you give us all of that. While there for FREE also they can bring their tester out and check your battery and alternator.

Without any troubleshooting, my first thought would be your coolant temperature sensor/switch for the computer. . .. . ...

I have attached information on that for your review.

ENGINE COOLANT TEMPERATURE SENSOR-PCM INPUT
The engine coolant temperature sensor is installed in the thermostat housing and protrudes into the water jacket. The sensor provides an input voltage to the Powertrain Control Module (PCM) relating coolant temperature. The PCM uses this input along with inputs from other sensors to determine injector pulse width and ignition timing. As coolant temperature varies, the coolant temperature sensor's resistance changes. The change in resistance results in a different input voltage to the PCM.

When the engine is cold, the PCM will operate in Open Loop cycle. It will demand slightly richer air-fuel mixtures and higher idle speeds. This is done until normal operating temperatures are reached.