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420A Crank shaft position sensors failure

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Looney Corleone

Probationary Member
6
0
Feb 8, 2019
Riverside, California
Ok first off i apologized if this qustion has been asked numerous times befor and im going to be honest im at the end of my rope researching the subject to death and would just like a stright honest answer even of the answer contains different variables
The qustion is what can cause a csps. To fail be replaced and fail a week later i sm at a loss. harnesis in good shape and as far as i know the pcm is also
 
Probably nothing short of physical damage from contact with the trigger wheel due to crankwalk or a chaffed wire somewhere on its pigtail.
 
Are you using a quality replacement, such as hitachi or mitsu? Cheap Rock Auto sensors are cheap
thank you for your input that's giving me something to consider because admittedly I did order a off brand crankshaft position sensor which if substandard quality is indeed the cause of the failure it will be returned and refunded and valuable lesson would have been learned
 
Probably nothing short of physical damage from contact with the trigger wheel due to crankwalk or a chaffed wire somewhere on its pigtail.
Okay going to be honest I've never heard of crank walk now that being said your suggestion raises more questions than it answers which is not a bad thing because it brings me one step closer to determining what the problem is . so my question now is what causes crank walk if that is indeed the case of the failure I'm going to need to know what causes it so I can understand how to repair it and to prevent it in the future so if you have a moment I would appreciate a brief or detailed lesson on what it is and what it will take to fix it and perhaps prevent it from reoccurring
 
I just noticed that you posted this in the 420a section, the 420a as far as I know was not prone to crankwalk. Crankwalk happens in an engine when the thrust bearing face of the center main bearing that the crankshaft rides on wears out, this bearing face is what keeps the crankshaft from sliding forward or backwards (walking) in the engine block, after this surface wears away the crankshaft can move forward when the clutch puts pressure against it when the driver is attempting to disengage the clutch, rather than disengaging the pressure plate, the crankshaft is easier to move when those bearings are gone and so force takes the path of least resistance and simply pushes the crankshaft away from the clutch and towards the crankshaft pulley (timing belt) side, this can allow the crankshaft trigger plate thats attached to the end of the crankshaft to come into contact and rub the plastic housing of the crankshaft sensor, ruining the sensor in short order, again the 420a is not known for this issue, but it can happen to ANY engine under the right wear conditions, the second generation 4g63 had SOME problems with this, not all of them but some of them did and thats why I recommended that as something to check before I realized you were working on a 420a. Its still something to check though.
 
I would start testing the harness and looking at the ECU, maybe measure supply voltage and check ground with voltage drop testing.

Crank walk shouldn't affect the sensor for a 420a as it's not a plate sandwiched in-between the sensor pickup, but a pickup on the outer circumference of a reluctor wheel on the crank. Crank walk may affect it's operation if it's moving far enough to lose pickup, but you'd notice ALOT of other problems before you saw that.

Otherwise quality of the sensor would be my question and concern. I've helped buddies replace several sensors on 420a engines for various reasons, but usually don't have an issue with a $25 O'Reilly's part.
 
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