# [SOLVED] Engine turns off while driving



## mab173

1999 Jeep Wrangler Sport, L6, 4.0L, 4x4 Automatic, 100,000 miles
Engine shunts down while driving, like turning the key off. After 5 to 15 minutes of rest, will start back up. This happens at random, may happen 3 times within 20 miles or 1 time in a 100 miles. Drove 15 miles and after 1.5 hours at rest, would not start. Towed home and then started back up. Have read possible issues: relay unit, grounds not making good contacts, check fuel flow fuel pump.:4-dontkno


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## evildead789

*Re: Engine turns off while driving*

Had this with my astra, very annoying and dangerous. Went to the garage, is just a sensor. no biggie


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## mab173

*Re: Engine turns off while driving*

Name of Sensor? o2? How does sensor affect the shut down?
Thanks in advance


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## Wrench97

*Re: Engine turns off while driving*

Not an O2 sensor, that would set a check engine light not shut it down, a crankshaft position sensor would cause a shut down, but more likely a ignition module, or fuel pump issue.


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## SABL

*Re: Engine turns off while driving*

Most common seems to be the crank position sensor.....don't know if they act spotty like what you are seeing. How's the weather in your area when these symptoms occur.....any rain?? My 98 had water dripping on the power distribution box making it hard to start. I pulled the connectors, cleaned and dried them, then reattached after a coating of dielectric grease on the contact points. No problem since then (3 yrs ago).


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## SABL

*Re: Engine turns off while driving*

Geez, wrench........you be lots faster than me. I didn't even see you in here when I started my post!!......:laugh:


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## mab173

*Re: Engine turns off while driving*

The weather has been dry and hot - TN, thanks for clearing up the sensor, 
would the starter relay have an issue along with as mention above?


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## wolfen1086

*Re: Engine turns off while driving*

As the owner of a 20019 Wrangler I feel like I might be a kinda expert on this issue.
This is NOT an o2 sensor, its NOT a throttle position sensor, if it was any sensor the check engine light will come on. heres the basic list of things to check
(1) battery
(2) fuel pump
(3) fuel system (filter lines for clogs, fuel rail for any minor leaks)
(4) engine ground
(5) ign coil
(6) coil wire)
(7) broken battery wires

Mine was easy a fuel pump and a battery did the trick.


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## evildead789

*Re: Engine turns off while driving*

you're probably right about that , when my engine turned off i still saw the lights on the dash. but no response on the ignition though.


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## Wrench97

*Re: Engine turns off while driving*

The starter relay would cause it not to crank, but would not make it shut off.


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## mab173

*Re: Engine turns off while driving*

Thanks to all for your support - its seems to boil down to the Crankshaft Sensor plus I'll check some of the other options...battery is new, E3 plugs, new coil wires...:wave:


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## Wrench97

*Re: Engine turns off while driving*

Usually a crank sensor will throw a code, I would look more to fuel or ignition for a sudden shut off problem.


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## mab173

*Re: Engine turns off while driving*



mab173 said:


> Thanks to all for your support - its seems to boil down to the Crankshaft Sensor plus I'll check some of the other options...battery is new, E3 plugs, new coil wires...:wave:



Replaced sensor and now has a rough idle, rpm's jump around. Is there timing involved with replacement of new sensor. Disconnected neg. gnd, but no change in idle, if so, then how to time? or reset?


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## wolfen1086

*Re: Engine turns off while driving*

I'd try a reset, do you know how?

I have the instructions for a 2.5 but I don;t know if they are the same for a 4L


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## mab173

*Re: Engine turns off while driving*

No access or knowledge to reset, any help will be greatly appreciated. Will try instructions for the 2.5, is it for manual or auto if that makes a different, auto for me. Maybe I can do a search for tuning/timing/reset??


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## wolfen1086

*Re: Engine turns off while driving*

Doesn't say on my instructions, give me 15 minutes from 2030 est to make a snapshot and link from here to image shack.


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## wolfen1086

*Re: Engine turns off while driving*

Ok Office 2010 won't let me make a picture out of it so here its long but it works I did it on my jeep 6 months ago after replacing the tps:

PCM Fast Learn Mode

The Jeep PCM performs several functions controlling Air Fuel ratios via Injector Bandwidth and Ignition Timing.

These outputs are controlled using the inputs received from all the sensors and then comparing these reading against a set of data tables burned into the PCM.

These memory tables are the brains that keep the engine running at low emissions and peak economy across the RPM band during closed loop mode.

These memory tables can and do change. They are adaptive, based on sensor readings, driving habits, engine performance and sensor tolerances.

Over time, the PCM Memory Tables become tuned to your engine.

This procedure first came to me from the folks at Avenger. I then verified it with a phone call to a Chrysler Engineer who had called me a year or so ago to ask about my experiences with a certain part on my TJ. I figured he owned me a favor. He had to check up on this for me. He called me back a week later and did indeed verify this procedure and what it does.

To the best of my knowledge it isn't documented in any of the FSM.



Forced Flash

This very simple procedure will Erase the Adaptive Memory stored inside the TJ PCM and allow a new Adaptive Memory to be developed.

After performing this procedure the PCM will re-learn and store into Adaptive Memory your engines performance characteristics.

Please perform these steps exactly as they are written, in the order they are written. This will cause the adaptive memory in the PCM to be erased and cause the PCM to go into Fast Learn Mode adaptive mode.





Disconnect the POSITIVE battery Terminal and touch it to ground for 30 seconds. (This is to discharge the PCM capacitors, which maintain the Adaptive Memory.
Reconnect the Battery Cable
Turn Ignition Switch to the On position but DO NOT start the engine
Turn Headlights On
Turn Headlights Off
Turn Ignition Key Off


The PCM Adaptive memory has now been flashed, or erased from the PCM.

When you start the engine it will be running off a set of pre-programmed tables that come with the PCM from the factory.

When you get the engine up to operating temperature the PCM will start to collect data for the Adaptive Memory.

The PCM will collect data for Adaptive Memory for the first 50 Warm-up Cycles.


Warm-up Cycle

A warm-up cycle happens when all of the following conditions exist.

Engine is running
A raise of 40F in engine temperature must occur ABOVE the engine temperature at start-up
Engine Coolant Temp must reach at least 160 F.


Once your engine has gone through 50 warm-up cycles in at least a 500-mile distance the PCM adaptive memory is set. It WILL NOT Change unless you flash it out and start all over again.


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## mab173

*Re: Engine turns off while driving*

Thanks wolfen1086 for the info, it has been a great relief to see that how easy it will be...will try 
would it make sense to replace the crank sensor in the distributor prior to erasing the memory?


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## wolfen1086

*Re: Engine turns off while driving*

Only if its bad, if its not bad then no don't replace it, If its doubtful and you'll lose sleep over it , then I'd replace it, but like wrench said it'll throw a code.
My best advice is make sure everything is operating properly before wiping, that way you get a fresh set of readings


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## mab173

*Re: Engine turns off while driving*

everything was running just fine prior to changing the crankshaft position sensor besides the engines turns off

what is the best way to check the sensor in the distributor?

I have been told that E3, Platinum or "cross-fired" plugs are not a good match for my 99 wrangler, just use factory or Champion truck plug number 4412
your thoughts?


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## mab173

*Re: Engine turns off while driving*

Tried method as mention as above...

installed new crankshaft position sensor > engine idles rough, replaced with old crankshaft position sensor > engine idles smooth, checked camshaft position sensor in distributor, while cranking engine: output from 0-5 volts.
plugs, wires & battery replaced prior to changing CKP.
Still get p1309, can reset, but returns. PCM > Pulse Code Modulation or Powertrain Control Module? Is the PCM in the engine compartment on firewall? What are the chances that the new crankshaft sensor is bad or does the engine have to warm up to get new signals over a period of time?


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## Wrench97

*Re: Engine turns off while driving*

If you do not get the P1309 code with the original sensor then the new sensor is defective or the incorrect sensor.


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## wolfen1086

*Re: Engine turns off while driving*

No Code = Good sensor, Code = bad sensor. The sensor sends signals to the computer at all times
As for the 1309 Code I can't help there my book doesn't even have that code and all I can find for it is for a Ford. But on Jeep PCM seems to mean Power Train Control Module


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## mab173

*Re: Engine turns off while driving*

Camshaft position sensor reads 0-5volts while turning the motor over. Getting feedback to replace the camshaft sensor. 
with new CKP engines idles rough, old sensor engine idles smooth...main issue with old CKP engines dies w/o notice.


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## wolfen1086

*Re: Engine turns off while driving*

I'm thinking its something else, unless the old sensor has a warm open somewhere in the unit itself.


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## mab173

*Re: Engine turns off while driving*

After replacing the Crankshaft position sensor with an aftermarket part. The sensor failed because it was missing a very important piece of the puzzle and no instruction/pictures.:4-thatsba
Bought new crankshaft position sensor from Chrysler Dealership...

Quote from Chrysler installation instructions:
"1. Be sure the paper/cardboard spacer has been installed to the bottom of the new sensor. If original sensor is being reinstalled (such as with transmission or flywheel removal), clean bottom of the sensor before installation. Obtain a new spacer and remove the paper backing. Install the self-adhesive side to bottom of sensor. This spacer MUST be installed. If spacer is not installed, sensor will be damaged when engine is started."

The aftermarket sensor did not come with a spacer and therefore it was damaged from the start!

After replacing with the sensor with spacer, it now runs good. Also had the dealership flash the settings and reset.:wave:


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## Midnight Tech

*Re: Engine turns off while driving*

Just checked ours on the shelf here at work - it has the spacer shim attached.


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## wolfen1086

Actually it wasn't defective just because it didn't come with a spacer shim, thats sold extra, I found that to be a Jeep thing, just like your floor pan plugs, go ahead and lose 1, gotta but a pack of 4 from the dealer, cause Advance doesn't have quite the right size.


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