96 Cherokee sport. I'm replacing my crank position sensor. very good help here on how to do the job.

here's my question: the crank position sensor doesn't seem to be essential to engine operation. I spend a lot of time with this rig in remote areas. for instance, i'll be driving to remote roadheads in the Bob Marshall Wilderness in Montana several times this summer. Can you bypass this thing if it fails and get the jeep running?

even if you have a spare with you, this seems to be an awkward replacement. is there a way to bypass it to get home?

 

I'm pretty sure it's involved with timing, fairly essential if I'm not mistaken.

 

I saw an explanation that said this thing was a safety device that would shut off the spark if you say, had an accident. if it doesn't sense the crank, no spark. so when it fails, you get no spark. from the shop manual I can't understand how it is involved with the timing. I got the impression its function was like that of say, a clutch safety switch- it stops something that the engineers think could be unsafe from happening, but isn't needed for the vehicle to run.

 

Then I imagine you'd have to mimic the pulse of the crank.

In my renix the ecu doesn't give spark until it sees 600 rpm, so I imagine it sees pulses when the crank rotates. I would think making something that mimics that pulse wpuld be way more labor intensive than just carrying and replacing a bad cps.

I've replaced 2 cps's, with the right tools it's not as bad as it seems, but that's just me. Some folks just want to reinvent the wheel.

 

Doen "The BOB!" Too cool! (I spent some time across the way at Glacier, on foot of course) Just carry a spare. The puter needs that signal or you are not going anywhere.

 

I've said it before and will no doubt say it again: There's one every day.....

 

Well.. "back in the day". There is actually a deal, some wreckers use it. It makes a rapid "buz" fire, replacing the dizy and the points and all that. You can go to a motor, hook that to the coil, jump it and crank. With a prime or starting fluid or some source of fuel, you can run a motor like that. I've see it at the wrecking yard, just to fire an engine to see it run.

I suppose it's not implosable you could have your injectors and coil going like crazy and still run....although you might be running away!

 

It is not possible to run without the crank sensor. No XJ ECUs or PCMs allow it. The crank sensor is what ALL timing is based from - the computer does not know the engine is spinning otherwise.

You may have been reading about the camshaft sensor. On Renix models it is not really required and will run without. OBD-I kinda runs ****ty if memory serves. OBD-II will panic.

If sensor failure is a real concern for you the get some spares. Hell get a handful from the junkyard. These are electronic fuel injection systems, the gadgets aren't just there for looks!

 

my problem is that I grew up working on vehicles without ECUs. timing was mechanical.

 

please explain. mine was an honest question. if this is an insult make it clear.

 

Well, I guess it's sort of an insult but it's more of just an observation about the amazing stuff that people can come up with. Even the most cursory search will tell you that the XJ fuel injected engine will not run w/o the equivalent of the CPS. There was a thread some months ago (maybe longer, time flies when you get to be ancient) asking the exact same question about bypassing or eliminating the CPS.

Where in the world did you see an explanation stating that the Crankshaft Position Sensor was just a safety device? Why would there possibly be thread after thread after never-ending thread about failure, testing and changing out the CPS if it was just an unneeded safety device.

Anyway, sorry if I insulted you. I guess it's better to ask than just removing the thing.

 

I remember seeing something about eliminating it. But no. I think you can eliminate the pcm if you know how. Something like gosh the crank shaft position sencor is telling the pcm when to get in and screw up your business.. I hate what dodge has done to jeep. And their trucks. Fing idiots. One more sign of the times. Not enough competition world wide. Population this customer base has gone threw the roof but how many new makers. Their owned by the few same as.....and you get screwed

 

7 year old thread.

 

I replaced the cpks on my 93 zj super easy. 2 bolts.
Took me a little while simply because my best friend was visiting.
Don't bypass this. Unless you don't mind your jeep stalling out at any given time.
I'm just learning all this auto mechanics stuffs.
I'm a grandma. If I can do it, you can.

 

WTF is this supposed to mean? I miss the good old days of proper grammar, spelling and sentence structure.