cherokeesporting

hi,

my 2001 cherokee sport likes to stall everytime the motor is cold.

outside temp does not make a difference as the car will start up and ilde perfect if the motor is slightly-full warmed up.

Its everytime you start it up when the motor is cold it will crank, fire up then immediately stall.

I have the cleaned the TB(its spotless) and put in a new IAC valve.

The problem still persist. So for now everytime I start the car cold I keep it running by holding the pedal about 1200 to 1500 rpm for 1 to 3 mins and then the car will start idling fine.

the motor is only slightly warmed up in those few mins and thats all it takes to get the car to idle perfect. It runs great other than this little issue,

thanks for any input! joined this forum to get some ideas as i dont know what to do next.

-zach

tjwalker

A marginal battery can give this symptom. As soon as the alternator gives it some joy, it doesn't give the engine management system trouble. Have the battery load tested. And yes, you can have a battery strong enough to start the engine, but marginal enough to create stalling.

Coolant temp sensor is another suspect. If that sensor provides incorrect data to the computer, it won't know what the actual temperature is. They can fail and not set a check engine light or code. Located on the thermostat housing.

cherokeesporting

why would the temp sensor mess up when the motors cold but then work perfect the rest of the time. The car gives zero issues as long as its slightly warm. it will fire right up and run great.

i would think a marginal battery would cause the stalling issue regardless of what the engine temp is.

im going to bring the battery into my work tmrw and un a load test on it thou anyway

cherokeesporting

battery tested fine.

any other possible causes besides coolant temp sensor?

Parhamm1

I know it sounds like an odd fix, but try the TPS. I think they're fairly cheap at napa/autozone. Worked like a charm for the stalling issues I had on my 2000 classic.

Parhamm1

Very easy to replace.... It's right next to the IAC on the TB

sycoglitch

X2. Let me tell you a quick tale. My battery tested fine and in cold weather I would have trouble starting and would have to rev a while. This happened bout month an a half ago. Checked the battery and the alt wire was lose under the terminal. Cleaned it all up dielectric greased it and shes good as new. It's an easy 10min job also clean terminals too. Oh and you will have all electrics as this happens

TheDutchy

Mine did the same thing until i changed the front o2 sensor...

moodster90

I have 2000 se model and I am having a stalling problem. I will look into all the suggestions you guys have made, thanks.

cherokeesporting

.ill try putting a new TPS in first.

id think if an o2 was bad it throw a code but who knows.

the car has no problem starting the battery cranks the motor over fine just stalls right after it starts. .ill check the alt terminal thou tmrw make sure its tight. the cable itself is fine with no corrosion.

moodster90

What's a TSP?

tjwalker

TPS = Throttle position sensor.
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The throttle position sensor is connected to the throttle shaft on the throttle body. It sends throttle valve angle information to the PCM. The PCM uses this information to determine how much fuel the engine needs. The TPS is really just a simple potentiometer with one end connected to 5 volts from the PCM and the other to ground. A third wire is connected to the PCM. As you move the accelerator pedal with your foot, the output of the TPS changes. At a closed throttle position, the output of the TPS is low, about a half a volt. As the throttle valve opens, the output increases so that, at wide open throttle, the output voltage should be above 3.9 volts. Testing can be performed with an electrical meter. Analog meter is best. You are looking for a smooth sweep of voltage throughout the entire throttle band. While slowly opening and closing the throttle, take note to the movement of the voltmeter needle. There should be a direct relationship between the needle motion to the motion of the throttle. If at anytime the needle moves abruptly or inconsistently with the movement of the throttle, the TPS is bad

You should have 5 volts going into the TPS. At idle, TPS output voltage must be greater than 200 millivolts. At wide open throttle (WOT), TPS output voltage must be less than 4.8 volts.. The best is to use an analog meter (not digital) to see if the transition from idle to WOT is smooth with no dead spots. With your meter set for volts, put the black probe on a good ground like your negative battery terminal. With the key on, engine not running, test with the red probe of your meter (install a paper clip into the back of the plug of the TPS) to see which wire has the 5 volts. One of the other wires should show .26V (or so). The other wire will be the ground and should show no voltage. Move the throttle and look for smooth meter response up to the 4.49 at WOT.

Perform the test procedure again and wiggle and/or tap on the TPS while you watch the meter. If you notice any flat spots or abrupt changes in the meter readings, replace the TPS.

The TPS is sensitive to heat, moisture and vibration leading to the failure of some units. The sensor is a sealed unit and cannot be repaired only replaced. A TPS may fail gradually leading to a number of symptoms which can include one or more of the following: -

NOTE: The throttle position sensor is also DIRECTLY involved with transmission shifting characteristics! It should be verified early in the troubleshooting process, when a transmission issue is suspected!

• Poor idle control: The TPS is used by the ECU to determine if the throttle is closed and the car should be using the Idle Air Control Valve exclusively for idle control. A fault TPS sensor can confuse the ECU causing the idle to be erratic or "hunting".
• High Idle Speed: The TPS may report faulty values causing the engine idle speed to be increased above normal. This is normally found in conjunction with a slow engine return to idle speed symptom.
• Slow engine return to idle: A failing TPS can report the minimum throttle position values incorrectly which can stop the engine entering idle mode when the throttle is closed. Normally when the throttle is closed the engine fuel injectors will be deactivated until a defined engine RPM speed is reached and the engine brought smoothly to idle speed. When failing a TPS will not report the throttle closed and fueling will continue causing the engine to return to idle very slowly.
• Engine Hesitation on Throttle Application: The TPS is also used by the ECU to determine if the driver has applied the throttle quicker than the Manifold Air Pressure sensor can read. The fueling is adjusted acordingly to cope with the sudden increase in air volume, however a faulty sensor can cause the ECU to ignore this data and the engine will "hesitate" when applying the throttle. In extreme cases with the engine at idle, a sudden application of full throttle can stall the engine.
• Engine Misfire: A fault TPS can report values outside the deined acceptable range causing the ECU to incorrectly fuel the engine. This is noticable as a slight misfire and can trigger the misfire detection software and/or Malfunction Indicator Lamp (MIL) light on the dashboard. Extreme cases can cause excessing misfires resulting in one or more cylinders being shut down to prevent engine and catalytic converter damage.

larryftmfw

Where can you order one of the tps's for an 04 grand Cherokee? Iv been having a very erratic idol, sometimes it sits at 600 and other times it stays at 800-1000.

Parhamm1

^autozone. They probably have one in sock. Just ask someone at that counter. Very easy to replace.

larryftmfw

Awesome, do my symptoms sound like a bad tps? I hope that's all it is.