96 dies after warmed up.

My 96 sputters and dies at an intersection after its up to operating temp. I replaced the coolant temp sensor but no difference. Crank sensor next? If so how do I test it?

I could be wrong, but i don't see what the coolant temp sensor would have to do with a stalling issue. Unless it's electronically controlled to say when engine hits x temperature to kill the engine to prevent engine damage. I guess that's possible, but honestly i don't know if such a system exists.

Here's the testing procedure for testing the CPS.

When my CPS failed it wasn't sputtering and then stalling it was literally just BAM stalled. You might want to describe your issue further.

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Troubleshoot and test, before you buy new parts.

The CPS is the most common failure, but not the only one that can cause a no-start.

The most likely cause of it cranks and cranks but won't start up is the Crankshaft Position Sensor (CPS) located on the transmission bell housing. Often this part is also referred to as the CranKshaft Position Sensor (CKP) CPS/CKP failure is very common. The CPS/CKP can stop working with no warning or symptoms and the engine will not run or the engine may randomly stall for no apparent reason.

Crank Position Sensors can have intermittent “thermal failure”. This means that the CPS/CKP fails when engine gets hot, but works again (and will test as “good”) when it cools back down.

Begin with basic trouble shooting of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. Jeeps do not tolerate low voltage or poor grounds and the ECM/ECU may behave oddly until you remedy this.

Symptoms –
- Starter cranks and cranks but engine won't start up and run.
- Fuel gauge and voltage gauge may not work or display properly.
- You sometimes will have No Bus on the odometer after 30-60 seconds.
- A failed CPS/CKP may or may not throw a CEL trouble code.
- No spark at the spark plugs.
- Fuel pump should run and prime for 3-5 seconds.

If the CPS/CKP is failed sometimes the OBD-II trouble code reader cannot make a connection to the ECU/computer or cannot read Check Engine Light/MIL codes because the CPS/CKP has failed. Disconnect the code reader, disconnect the CPS/CKP wire connector, and reconnect the code reader. If the code reader establishes contact with the ECU and scans, your CPS/CKP is failed and needs to be replaced.

Diagnostic steps to confirm the CPS is the cause of your no-start

You should be able to verify a bad cps, by unplugging it, and turning the ignition key to on. If the voltage gauge and/or the fuel gauge now displays correctly, replace the CPS.

Unplugging and reconnecting the CPS sensor where it connect to the main harness near the back of the intake manifold usually resets the ECU and if the jeep fires right up after doing this you can bet that the CPS is faulty and needs to be replaced.

Exchange the fuel pump relay and the ASD relay with one of the other similar ones in the PDC to eliminate the relays as the cause of the no-start. Confirm that the fuel pump to runs for 3-5 seconds when you turn the ignition key to ON.

Eliminate the NSS as a cause of no start. Wiggle the shift lever at the same time you try to start. Put the transmission in Neutral and do the same. Do the reverse lights come on when the shifter is in Reverse?

Inspect the wires and wire connectors at the O2 sensors on the exhausts pipe. A short circuit from melted insulation or from broken O2 sensor wires can blow a fuse and the ECU/ECM will loose communication. Don’t get tunnel vision and assume the sensor is bad (unless it tests bad with a meter). Damaged wiring or a dirty connector can inhibit the signal from making it to the computer. Inspect/test/clean/repair wiring or connectors as necessary.

CPS Testing

Crankshaft Position Sensor Connector (CPS/CKP)





TESTING PROCEDURE 1991 – 2001 4.0L H.O. engines

1. Near the rear of intake manifold, disconnect sensor pigtail harness connector from main wiring harness.
2. Place an ohmmeter across terminals B and C (See Image). Ohmmeter should be set to 1K-to-1OK scale for this test.
3. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

TESTING PROCECURE for 1987 – 1990 4.0 L engines

Test # 1 - Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the CPS and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 – 275 Ohms. . If the CPS is out of that range by much, replace it.

Test # 2 - You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.

The 2000 and 2001 will have the CPS in the same location on the bell housing, but the wire connector may be on the passenger side, not as shown in the diagram below. Simply follow the wire from the sensor to the connector.

Thanks for the help. Ill give it a test.

Does it die immediately after warming up, or after a while of being hot?

It dies a while after warming up. It spits and sputters for about 30 seconds then quits. if i turn the ignition off for a minute and then restart, it runs and idles fine for about 15 minutes and dies again. I just replaced the crank sensor and still no change.

After the crank sensor, the #2 cause of thermal ignition failure on the 4.0 is the ignition coil.

I would keep a meter handy and test it for primary/secondary resistance values as soon as the engine stalls.

Please tell me what you end up finding this being. I am having this *exact* same symptom on my 2000 XJ. It only happens after the rig is warm and it happens whenever you stop at a light and you sit for a few seconds, then it sputters and dies. Restart it and you're golden for another 10+ minutes.

All the symptoms described with the CPS don't seem to match the issue though.

When speaking about the idle air control valve, are you suggesting cleaning or replacement?

Anything else that could be looked at?

Thanks!

Justice231, any luck so far?

I filled up the tank, added some injector cleaner and it ran fine. I drove it around town and trail for a couple weeks without incident. Last trail trip it ran great until I splashed though a large puddle and 15 min later same thing (sputter and stall after left at idle for 5 min). After I got home i cleaned the idle air control valve and still no change.

What do I replace next?

Thanks

I would start with checking electrical harness connectors for moisture or corrosion.

It's been hot and dry for the last week and I cleaned all kinds of plugs and connectors. Still the same problem. I barrowed a code reader from a friend and got p0171 and p0172 codes. The code book says 171 is running to lean and 172 says to rich. Thinking about perchacing a IAC or TPS next.

Running lean and rich can be caused by a malfunctioning MAP sensor and a leaking vacuum tube for the MAP sensor or a bad O 2 sensor.
You also might have a vacuum leak between the intake and head.

Just for giggles crawl underneath and look at the rear O2 sensor, make sure the tie down for the pigtail didn't come loose and it is isn't cooking on the CAT.
Might as well check the front O2 wire also.

Next best guess is a failing ignition coil. I've touched the side of the coil and it was so hot it put a blister on my finger. Normally they don't get that hot.

Been my experience the IAC is worse when it's cold, but can screw up most anytime. When it starts screwing up most of the time it is usually related to a battery or charging issue. I went through something similar not long ago, I had a weak cell in my battery. That cell and the whole battery just up and died completely, zero volts, from one minute to the next, which was a first for me.

Ok I'll keep plugging away. Thanks for all the help, much appreciated. Ill let you guy know what I come up with.

Having a '96 that was giving the same codes and having similar running problems, it came down to having to replace the fuel pressure regulator that is mounted above the fuel pump in the in-tank fuel delivery module. Beware of replacement regulators with a 35psi working pressure, they will cause these codes and problems.
Borrow a fuel pressure gauge from a friend or Autozone and check the fuel pressure at the rail fitting. It should read 50psi + - 2.
The other possibility is a clogged fuel filter...

First, second and third thing I would have checked would be the front O2 sensor wires, fuse and power to the heater in the O2 sensor and the O2 sensor.

justice231 said:

It's been hot and dry for the last week and I cleaned all kinds of plugs and connectors. Still the same problem. I barrowed a code reader from a friend and got p0171 and p0172 codes. The code book says 171 is running to lean and 172 says to rich. Thinking about perchacing a IAC or TPS next.

Click to expand...

i second ecomike's statement about checking out the front o2 and it's wiring. a couple years ago, my '96 did pretty much the same thing.
it was fine when first started-especially cold, but as soon as it was fully into closed loop and warmed up, it stumbled and ran like poo. i got the same codes as well.
turned out the front o2 was bad, i think i killed it when i DOUSED it in brake cleaner accidentally.