NAXJA Forums -::- North American XJ Association  

Go Back   NAXJA Forums -::- North American XJ Association > NAXJA Unibody Jeep Technical Forums > Jeep Cherokee XJ (1984 - 2001) > OEM Tech Discussion
HOME Member FAQ Sponsor Info Rules Bylaws E-Mail

OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs.

Reply
 
Thread Tools Display Modes
  #1  
Old April 22nd, 2019, 14:54
Smittysjeep15 Smittysjeep15 is offline
NAXJA Forum User
 
Join Date: Dec 2018
Location: New Hampshire
Posts: 4
98 4.0 when warm stumbles then dies

I have a 98 4.0 that will start run for about 30 mins then start to stumble. Then no throttle respons then die. Then it will crank and not start. Untill cooled down. I have tested TPS at volts.77 at idle then WOT it's at 3.77. it has spark when running and spark when it's only cranking. When it dosnt want to start. No DTC. Could temp sensor be failing telling ecu to shut down. Engine seems really hot IR temped near the temp sensor at 225 to 230 F then when therostat opens drops to 200 to 215. Running out of ideas that it could be. Thanks
Reply With Quote
  #2  
Old April 23rd, 2019, 04:16
Tim_MN's Avatar
Tim_MN Tim_MN is offline
Freakish Hand Strength
 
Join Date: Mar 2003
Location: Minneapolis, MN
Posts: 7,114
Re: 98 4.0 when warm stumbles then dies

I think your TPS is out of specification. It should be closer to .25 volts at minimum throttle opening (idle), to 4.8 volts at WOT wide open throttle.


TPS failure may have one or more of these Physical Symptoms:

1) The engine loses power and is stalling.
2) The engine will idle, but may die as soon as you press the gas pedal. When driving, it seems as if all power is gone.
3) Sometimes it feels as if the transmission is failed or isn't shifting properly, if at all. If you quickly jump on the gas you might be able to get the transmission to shift, but it won’t shift properly by itself. Shifting manually, the transmission goes through all the gears.

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

TPS TEST

The TPS is mounted on the throttle body. The TPS is a variable resistor that provides the Powertrain Control Module (PCM) with an input signal (voltage)that represents throttle blade position. The sensor is connected to the throttle blade shaft. As the position of the throttle blade changes, the resistance of the TPS changes. Along with inputs from other sensors, the PCM uses the TPS input to determine current engine operating conditions. In response to engine operating conditions, the PCM will adjust fuel injector pulse width and ignition timing.

The PCM supplies approximately 5 volts to the TPS. The TPS output voltage (input signal to the PCM) represents the throttle blade position. The PCM receives an input signal voltage from the TPS. It is best 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. This will vary in an approximate range of from .25 volts at minimum throttle opening (idle), to 4.8 volts at WOT wide open throttle.

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:

-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.


Cheap crappy "Lifetime Warranty" parts are often out of specification or even failed right out of the box. Many times they have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep sensors.
__________________
.
.

Quote:
Originally Posted by bimmerjeeper


Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Reply With Quote
  #3  
Old April 23rd, 2019, 17:09
trippled trippled is offline
NAXJA Forum User
 
Join Date: Apr 2006
Location: colorado springs, co
Posts: 2,336
Re: 98 4.0 when warm stumbles then dies

I would also verify fuel pressure when the problem is occurring.
Reply With Quote
  #4  
Old April 30th, 2019, 06:42
MichXJdad's Avatar
MichXJdad MichXJdad is offline
NAXJA Forum User
 
Join Date: Apr 2019
Location: Detroit Rock city
Posts: 93
Re: 98 4.0 when warm stumbles then dies

Seems kinda hot to me. Maybe heat soak?? I had a similar problem I just fixed this past weekend, I installed a new IAC and it's good to go. I didn't have an issue with hi temps though. I see you're a fellow northerner, engine temp shouldn't be that hot this time of year in my opinion.
Reply With Quote
  #5  
Old April 30th, 2019, 07:16
Tim_MN's Avatar
Tim_MN Tim_MN is offline
Freakish Hand Strength
 
Join Date: Mar 2003
Location: Minneapolis, MN
Posts: 7,114
Re: 98 4.0 when warm stumbles then dies

Heat soak is almost always starting issue. Once running any heat related stumbles should clear immediately with a few revs on the gas pedal. Excessive temperatures at idle show the need for cooling system maintenance, often the fan clutch is weak and/or the thermostat needs replacing.
__________________
.
.

Quote:
Originally Posted by bimmerjeeper


Go ahead and slam the liftgate down on a blanket, and see how long you are laughing.
Reply With Quote
  #6  
Old May 1st, 2019, 11:02
MichXJdad's Avatar
MichXJdad MichXJdad is offline
NAXJA Forum User
 
Join Date: Apr 2019
Location: Detroit Rock city
Posts: 93
Re: 98 4.0 when warm stumbles then dies

I agree too hot, Is the auxiliary fan coming on at 215? Mine will start with heat soak, and run like shit for about 20-30 seconds, but an engine will not restart when it is too hot. Cooling system was my first suspect. Do a flush and refill on the cooling system, Matt from bleepinjeep has a great youtube video for that. New thermostat, and see how it runs. It's cheap maintenance. I plan on swapping in a 180* thermostat
Reply With Quote
  #7  
Old May 1st, 2019, 14:09
Dragonslayer Dragonslayer is offline
NAXJA Forum User
 
Join Date: Feb 2004
Location: Los Angeles
Posts: 311
Re: 98 4.0 when warm stumbles then dies

Check the O2 sensor with a graphing scanner (not a code reader). When at operating temps
the O2 sensor graph should show rapid and sharp peaks and valleys (telling the ECM how to
meter the fuel and adjust the timing). If there are any wide flat lines, then either the
O2 sensor wire harness, connector, or the sensor itself is/are suspect.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
01 XJ 4.0 starts stumbles then dies BIGDOGGP739 OEM Tech Discussion 9 November 27th, 2016 19:00
88 xj stumbles when warm timthecleric OEM Tech Discussion 4 September 3rd, 2009 20:43
Dies when warm redneck OEM Tech Discussion 22 April 9th, 2007 23:09
'86 2.5 TBI, stumbles/dies at idle, very rich, failed emissions... CameronB OEM Tech Discussion 2 September 17th, 2006 15:45
4.0 stumbles when warm starting? Tronner OEM Tech Discussion 2 July 20th, 2005 07:11


All times are GMT -7. The time now is 05:25.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
NAXJA and NAXJA logo's Copyright NAXJA. All content/images Copyright NAXJA 1999-2014