A big headache due to crankshaft sensor failure

I don't know how often this failure may occur in your vehicle or probably it has never happened to you, maybe it depends on the make or model of your car, but occasionally it happens that the crankshaft sensor may start to fail and from there generate a cataract of doubts to determine where the problem is, I say this because when the mentioned sensor fails it can be easily confused with other things. Sudden shutdowns, spark failures and idle failures, those were the symptoms I experienced when the issue started to become a headache.

For those who don't know, the crankshaft sensor is in charge of determining the position and speed of the crankshaft, it sends a signal to the computer with the mentioned information so that from there the car starts to operate accordingly. I learned the above as I was reviewing the failure with my mechanic and the truth is that I had not had problems with the sensor since I have the car.

Going to my experience, the first thing that happened was that the car turned off suddenly and I had to wait a few minutes for it to turn on again, but only to turn off again a few minutes later and so on. Considering that at no time did the service light come on, we ruled out sensor faults, so the first thing that occurred to us was that the fuel pump battery was failing, however, after running several tests we determined that it had no problem.

Then we changed the fuel pump relay and from there it seemed that everything was solved, but a few hours later the same thing happened. So, looking in other places, we noticed that when the truck was turned off, it did not start again because there was no spark, but it returned after a few minutes, so we concluded that it was the crankshaft sensor as it is responsible for generating the spark and fuel injection. We replaced the sensor and everything was solved, but after a month the same problems returned.

I have already mentioned that I have a 1994 Jeep Wagoneer Limited, these, like the Cherokee XJ's of the 90's, have the sensor located in a very difficult to access place between the engine and the box, replacing this sensor can be stressful if you don't have the right tools. I just mentioned where it's located to point out that it's in a place where it gets all the heat from the engine and case, and well, these trucks are notorious for being very hot engines. So, based on the above, the sensor gets a lot of heat stress in its original location and that can cause it to fail over time even if you're using an original sensor.

My brother in law, who is my mechanic, has a Cherokee XJ and knows it perfectly well, he went through the same thing some time ago and to solve it and avoid the same recurring failures, he decided to change the sensor location, does it seem crazy what you just heard, well yes, there are few sensors that can be manipulated in terms of location and even more so the crankshaft sensor since it is a positional sensor.

How did he do it, well, obviously he had to investigate, practice and fail several times until he was able to achieve it, and that was through the development of a phonic wheel attached to the front of the engine where it receives much less heat. This phonic wheel emulates, by its particular shape, the element from which the sensor was originally fed, making it work in the same way.

To make the phonic wheel, very precise blacksmithing skills are required since the grimaces or spaces seen in the photos must be perfectly spaced for the sensor to work properly. It requires a thick metal sheet which is shaped according to a model made on paper which serves as a guide for cutting and molding of the metal sheet, this, as I mentioned, adheres to the dámper which must be perfectly balanced.

So after having done the work, I am confident that I will not talk about that sensor for a long time, it will work there much cooler and that will extend the life of its internal components, which deteriorate faster in such a hot environment as the junction between the engine and the box.

The truck feels even better, it seems that somehow the sensor transmits the information more efficiently, the idle is much more stable and the throttle response improved, so the whole job was a success. I am impressed how my brother-in-law was able to elaborate this phonic wheel that will save us so many problems in the future, he is definitely a genius. What I just told you was my particular experience with the model of truck I have, maybe you will never have this problem, but if the same thing happens to you as to me, you know that there is another alternative.