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Random Stalling/Replaced Crankshaft Position Sensor


Old 01-05-2010, 02:19 PM
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Default Random Stalling/Replaced Crankshaft Position Sensor

I have a 2001 SLE with 221,000 miles on it and have been having stalling issues for the last 4 months. It finally was happening to often to where it was unsafe to drive it anymore until I could fix it.

My Symptoms:

1. Stalls with codes being set. Many saying random misfires. On one ocassion I got a code pointing to the crankshaft position sensor.
2. Stalls with no codes being set
3. Engine stumbles for just a second at freeway speed but does not set codes and keeps running.
4. Engine stumbles for just a second at freeway speeds and does set a code and keeps running.
5. Engine stumbles for just a second, the tach drops to zero and the gas mileage drops from 30mpg to 25mpg and keeps running. Pull over and turn engine off and restart it and everything corrects itself then runs fine the rest of the day.
6. Stalls and engine restarts right away
7. Stalls and engine cranks but will not restart till about 20 minutes later. Does anybody know what is going on with the engine for those 20 minutes?
8. Engine will always start when it is cold.
9. Numerous times I have driven somewhere with no problems and come back to start the car 30 minutes later and had no start engine cranks then waited till the engine was cold and it started right up.

I replaced the wires and plugs which made no difference. Next I replaced the ignition module still same problems. Next on the list was the crankshaft position sensor. Was not looking forward to tackling that job. Called the dealer and they wanted $200.00 ($70 for the sensor and $130 for labor) to do it. Saw many horror stories on the net where people threw lots of money away having the dealer guess what parts to replace and decided that I would do it and save some money for other parts that may be needed if this didnít solve the problem.

The part was $35.00 at OReilly. I rented 2 harmonic balancer pullers, one from OReilly and one from Advance. Biggest concern was how to keep the crankshaft from turning while trying to loosen the harmonic balancer bolt. There is a tool that Kent Moore makes that holds the flywheel for $87.00 part # J-37096. Somebody on this site said that there are holes in the flywheel that you can wedge a screwdriver in and let it rest against the engine while turning the bolt. It turns out that they were correct because that is what I was able to do. It did take a breaker bar and a 2 foot piece of pipe in order for there to be enough torque on the bolt to get it to turn. I had to remove the 2 plastic inspection plates next to the starter to get at the flywheel. I also removed the starter so that the screwdriver would rest against the bottom of the block and not the starter. If you remove the starter be sure to disconnect the battery cable from the battery BEFORE removing the starter. I almost forgot to do that myself. Like I said earlier I did need to use a breaker bar and a 2 foot piece of pipe in order for the bolt to loosen. I was afraid that the screwdriver may sheer off but it did not. Just besure to use the biggest screwdriver possible and be careful because you will be applying lots of torque to that bolt.

The puller from Advance Auto Parts looked to be stronger then the one from OReilly so that is the one I used. Only problem was no bolts from the Advance puller were small enough in diameter to thread into the holes of the harmonic balancer so luckily I was able to use the small bolts from the OReilly Kit with the Advance puller. Before attaching the puller you need to remove the serpentine belt and insert a push rod from the Advance kit into the center bolt hole in the crankshaft. Attach the Advance puller with the OReilly bolts and besure that the push rod is line up with the big center bolt of the puller. Start turning the center bolt on the puller. The harmonic balancer came off pretty easily.

Now you have to remove the plastic cover that shields the sensor. Do this by carefully prying it off from the 3 pins that hold it in place. Remove the 2 bolts that hold the crankshaft position sensor to the engine. Install the new sensor. Tighten the bolts to 22 lb ft. Put some dielectric grease on the connector and connect it to the new sensor. Clean the shield and reinstall it. Clean the back side of the harmonic balancer and reinstall it so that the groove lines up with the key in the crankshaft and push it on as far as it will go. They rent harmonic balancer installers for putting the harmonic balancers back on but I was able to use the bolt to pull it all the way on. I did have to put the screwdriver back into the flywheel and let it rest against the oil pan while I tightened up the bolt. Alldata said to torque the bolt to 111 lb ft and then another 76 degrees. I marked the head of the bolt so that I could tell when I got to 76 degrees. In knowing that the screwdriver was pushing against the oil pan it made me wonder how much pressure the oil pan could take before it would crack so I stopped at about 45 degrees past 111 lb ft. I marked the head of the bolt and figured that I would keep an eye on it just incase it might start to loosen. So far so good. Reinstall the serpentine belt.

It has been about 3 weeks and so far no problems.

I saw to many similar post with no resolution and not enough info so I was determined to pass along as much info as I could so others could learn from my experience. Hope this was helpful.
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Old 01-05-2010, 02:31 PM
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Great info and thanks for taking the time to write this up. I hear ya on the torque specs.....kinda makes you cringe when you get to the point where you wonder if tools and body parts can take it or not.
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Old 05-31-2012, 12:56 AM
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Default Very correct

Just wanted to add that my 97 Pontiac Bonneville SSE 3.8 did the same thing untill I changed the sensor so far no problems. Only thing I did different was use a Impact gun to get the bolt off. You wont have to worry about the crank turning, well not enough to worry about. Check the torque and go another 75 after you put the belt back on. But if you have a gun and a torque bar use that.
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