wrpdrive26
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So, after several weeks of poking and prodding, we finally found the problem to my mystery stalling issue. It ended up being the crankshaft sensor, the one towards the back of the engine. I believe it is crankshaft sensor B. It appears the internals on the sensor were going out, so once the engine was warmed up, the sensor would start dropping out. When the sensor would drop out, that very second, the engine would stall since the PCM now had zero data to go on. So watching it on the scanner, we didn't see anything unusual. My mechanic said, these cars are equipped with two of these sensors. One is responsible for higher engine speeds, and the other is responsible for lower engine speeds. The crankshaft sensor on the back, is the low engine speed sensor, which explains why it would stall out only at idle under 1,000 rpm.
Some back story, so hopefully if anyone else comes across this issue, it may be of some service. One day when I was leaving work, I was letting the engine warm up in the parking lot. Suddenly, the engine started running really rough. The check engine light came on flashing. I shut the engine off and tried a restart. She really did not want to start, but eventually did, but ran rough and very quickly stalled out. My gas gauge has been busted for a while, and I was at the mileage when I usually fill up. To rule out no gas, I walked next door to the gas station grabbed a gallon and put it in the tank. She still didn't want to start or run. Ended up calling AAA and having my car towed into the shop. The only code that was present was the generic P0300 multiple/random misfires detected. Since this was very similar tow when my ignition control module failed, that's where the mechanic started. He found the ICM to be overheating and cracked. So he ordered a new Delphi unit and was installed it. The previous one was aftermarket, I don't know the brand. That got the car to run a little smoother. However, there was a new symptom that was being masked before. The engine would randomly stall out at idle. There were no PCM codes to indicate anything. Checking the live data, there was nothing jumping out to indicate any particular sensor was to blame. The mechanics were stumped.
So they started checking the other modules in the car to see if anything jumped out at them. Upon further inspection, they found the anti-theft module was dropping out (this would probably explain why my security light would come on at times). So, they were able to find an old-new stock OE anti-theft module and ordered it thinking maybe when the module dropped out, the vehicle would believe it was being stolen and would shut off. That didn't solve the stalling issue, but got rid of the anti-theft codes (so that would have probably been a problem later down the road anyway, especially since the my light was coming on at times). At this point, we were stumped and figured this had to be an electrical issue somewhere. He asked me to pull some parts from a donor Aztek that I have, which was my first ever car, that I have in storage for parts/to potentially fix up one day. While he waited for me to do that, he ordered a new ignition switch to try. That didn't work so he sent the new one back. I pulled the engine bay fuse box and the PCM out of that one and took them to my mechanic. He swapped them around, and that still didn't fix it. He was hoping maybe by switching the PCMs the new one may pick up on the problem and throw a code, which it didn't. So he started probing wires and seeing if he could see any voltage drops. I stopped in many times while this was going on. Giving him suggestions from people on here and on other pages. We tried cleaning the MAF, checked the IACV. Nothing was changing the outcome. At some point, they discovered that it would only stall at low idle. When the car would call for 750ish rpm. If they held the throttle down and got it to idle at 1,200 rpm, it would keep on running.
Finally, the mechanic and his dad (owner) started pulling out every fuse, one by one, and unplugging sensors putting the car into bypass mode for many of the sensors waiting to see if the stalling issue would either go away or get worse. They got to the alternator. They unplugged it and suddenly the car ran for over an hour without stalling. They thought they finally found the problem. And then the car stalled, lol (it was hooked up to an outside power source during this time). That's when the mechanic finally got to the crankshaft sensor on the back of the motor. He unplugged it and suddenly the car stalled in the exact same manner it has been. Quick and sudden. He plugged it in and the car ran. Unplugged it again and it stalled immediately. On a whim, he ordered a new Delphi crankshaft sensor. I happened to stop in right when he was finishing the install and was about to start it up. He hopped in and she roared to life right away, smoothly, without hesitation. She came down to idle and not once stalled in the over 30 minutes we stood around watching it. At that point, he was confident that was the issue. I left while they left it running for a while to see if it would stall out at all. It never did. She kept on running.
So, I hope this little escapade helps others in the future. If you find yourself with a mystery stalling issue with zero codes, my recommendations for the first two parts to check out and/or replace would be the ignition control module and the crankshaft sensor b. This thing has sent us around in circles, and unfortunately this wasn't the first time. The previous time an Aztek of mine had something like this, it was the ignition module. That's why we both immediately jumped to that conclusion at first. I love this car, but boy does she make the mechanic work for their money.
Some back story, so hopefully if anyone else comes across this issue, it may be of some service. One day when I was leaving work, I was letting the engine warm up in the parking lot. Suddenly, the engine started running really rough. The check engine light came on flashing. I shut the engine off and tried a restart. She really did not want to start, but eventually did, but ran rough and very quickly stalled out. My gas gauge has been busted for a while, and I was at the mileage when I usually fill up. To rule out no gas, I walked next door to the gas station grabbed a gallon and put it in the tank. She still didn't want to start or run. Ended up calling AAA and having my car towed into the shop. The only code that was present was the generic P0300 multiple/random misfires detected. Since this was very similar tow when my ignition control module failed, that's where the mechanic started. He found the ICM to be overheating and cracked. So he ordered a new Delphi unit and was installed it. The previous one was aftermarket, I don't know the brand. That got the car to run a little smoother. However, there was a new symptom that was being masked before. The engine would randomly stall out at idle. There were no PCM codes to indicate anything. Checking the live data, there was nothing jumping out to indicate any particular sensor was to blame. The mechanics were stumped.
So they started checking the other modules in the car to see if anything jumped out at them. Upon further inspection, they found the anti-theft module was dropping out (this would probably explain why my security light would come on at times). So, they were able to find an old-new stock OE anti-theft module and ordered it thinking maybe when the module dropped out, the vehicle would believe it was being stolen and would shut off. That didn't solve the stalling issue, but got rid of the anti-theft codes (so that would have probably been a problem later down the road anyway, especially since the my light was coming on at times). At this point, we were stumped and figured this had to be an electrical issue somewhere. He asked me to pull some parts from a donor Aztek that I have, which was my first ever car, that I have in storage for parts/to potentially fix up one day. While he waited for me to do that, he ordered a new ignition switch to try. That didn't work so he sent the new one back. I pulled the engine bay fuse box and the PCM out of that one and took them to my mechanic. He swapped them around, and that still didn't fix it. He was hoping maybe by switching the PCMs the new one may pick up on the problem and throw a code, which it didn't. So he started probing wires and seeing if he could see any voltage drops. I stopped in many times while this was going on. Giving him suggestions from people on here and on other pages. We tried cleaning the MAF, checked the IACV. Nothing was changing the outcome. At some point, they discovered that it would only stall at low idle. When the car would call for 750ish rpm. If they held the throttle down and got it to idle at 1,200 rpm, it would keep on running.
Finally, the mechanic and his dad (owner) started pulling out every fuse, one by one, and unplugging sensors putting the car into bypass mode for many of the sensors waiting to see if the stalling issue would either go away or get worse. They got to the alternator. They unplugged it and suddenly the car ran for over an hour without stalling. They thought they finally found the problem. And then the car stalled, lol (it was hooked up to an outside power source during this time). That's when the mechanic finally got to the crankshaft sensor on the back of the motor. He unplugged it and suddenly the car stalled in the exact same manner it has been. Quick and sudden. He plugged it in and the car ran. Unplugged it again and it stalled immediately. On a whim, he ordered a new Delphi crankshaft sensor. I happened to stop in right when he was finishing the install and was about to start it up. He hopped in and she roared to life right away, smoothly, without hesitation. She came down to idle and not once stalled in the over 30 minutes we stood around watching it. At that point, he was confident that was the issue. I left while they left it running for a while to see if it would stall out at all. It never did. She kept on running.
So, I hope this little escapade helps others in the future. If you find yourself with a mystery stalling issue with zero codes, my recommendations for the first two parts to check out and/or replace would be the ignition control module and the crankshaft sensor b. This thing has sent us around in circles, and unfortunately this wasn't the first time. The previous time an Aztek of mine had something like this, it was the ignition module. That's why we both immediately jumped to that conclusion at first. I love this car, but boy does she make the mechanic work for their money.
