Seeking a tutorial for cutting a hole in the floor to reach CPS

[NC Tom]

Folks have done it, but has anyone documented it?

[89 MJ]

You shouldn’t need to do that. I can get to mind from either underneath or the engine compartment. 

[NC Tom]

4 minutes ago, 89 MJ said:

You shouldn’t need to do that. I can get to mind from either underneath or the engine compartment. 

You are correct. Don't "need" to. But, it's such a PITA and takes way too long. I have to go underneath with 6+ extensions all while laying on cold, sharp gravel. It's unpleasant enough to want to just cut a dang hole.

[89 MJ]

21 minutes ago, NC Tom said:

You are correct. Don't "need" to. But, it's such a PITA and takes way too long. I have to go underneath with 6+ extensions all while laying on cold, sharp gravel. It's unpleasant enough to want to just cut a dang hole.

Not wanting to lay in the gravel is understandable. I’m not sure that pulling the carpet back and then having to work around the pedals is going to be a much better experience, but everyone has their preferences. 
Did you try getting it from the top side?

[jpnjake]

I just did mine from underneath with a swivel head ratchet, and a wrench, just used an xj trunk Mat for something to lay on to keep myself comfortable. Way easier from underneath than up top, and definitely gonna be hard to get to from  inside, even with cutting the floor since it’s up on the firewall behind the dash area. 

[Spinnakerblue89]

Look, I know this may not be an answer you are hoping for, but just bear with me please, I promise it's not bad at all when you don't box yourself in. 

 

Sometimes you just have to take a step back for a moment and see other angles. 

 

Last year I replaced the CKPS on my ZJ 4.0 with minimal problems. Here is how I did it:

 

Generously soak the sensor bolts with penetrant like Liquid Wrench or PB Blaster for a day. The last thing you ever want is for a seized bolt to break off in that spot.

 

1- First decide how much of a socket extension you require to reach the sensor from underneath the driver side.

 

2- build that extension lol.

 

3- at the end of your extension, attach a socket swivel. Now, here is the key part to this, *TAPE* that swivel. I wrapped around it, maybe three times. Why? A great source of frustration with doing this job is an overactive swivel, by taping it, it still has a range of motion, but it's stiffer. 

 

4- attached a few feet of string to your new sensor, maybe 3 or 4 feet probably. Obviously color doesn't matter, but I used neon pink because it's easy to see in my engine bay. 

 

***Be sure your sensor is connected securely before you continue***

 

5- use that string to guide the new sensor down to the hole where it goes, and do this from above in the engine bay. 

 

6- use your sick extension with the taped swivel to guide the bolts in from down below.

 

7- life's good, don't worry about the string, mine is still in my ZJ. 

 

A little advice. If you follow this steps, and you still get frustrated, just walk away for a bit. Getting frustrated on this job is never going to end well. I did the job in 30 mins tops, including after I got flustered and stepped away to regroup. I've heard grown men say it took them all weekend to do this job, I ain't about that. And for the love of God, don't cheap out on the sensor. I used an NTK and it's been since last September that I did the job. 

 

I hope that helps you because brother, cutting should be a last resort. 

[rokinn]

From below I use a 12" wobble extension and electrical tape in the socket to hold the bolt (it's not a swivel).  I think it's only one more 6" extension but could be two, don't recall for sure.  I never have any problems with this approach.  Easy as cherry pie!

[ThatJeepGuy]

For the level of work and time involved with any level of respectable, serviceable approach to an access panel to "quick change" your cps - you could just change out your cps and be done with it.

 

On the other hand if you don't care one bit on the How - just that it's done quickly- well surely a big enough hole saw and some swear words later and you'll have exactly what you desire - a gaping access hole 

[NC Tom]

Thanks all for chiming in. I have removed the CPS before and replaced it with a new one that didn't work and put the old one back on. So, I know how to do it. It's just a stupid place to put something so important. In my opinion. Electrical is not my forte, so I get annoyed very quickly when things don't work.

 

I just figured creating a hatch for easier access would be a good thing.

 

And @ThatJeepGuy It wouldn't be a "gaping access hole". It would be a nice, clean, port, with a hinged lid, lined with carpet and lockable.

 

[Spinnakerblue89]

Yeah it does suck the location, but for all its faults, I can't say it's completely inexcusable, I believe the idea was to keep the sensor away from water and mud at the time. Have other manufacturers done it better? Perhaps.

[AZJeff]

Many engines locate the CPS at the front of the engine, and get the trigger pulse from a point on the front crankshaft pulley or harmonic balancer.   
 

I wonder why Jeep did not choose a similar solution, until I started studying the layout of the front of the engine.
 

I concluded that on an MJ/XJ with the 4.0, due to the extremely limited space in that part of the engine bay, fitting the CPS in the front would be challenging, to day the least.

[ThatJeepGuy]

11 hours ago, NC Tom said:

 It would be a nice, clean, port, with a hinged lid, lined with carpet and lockable.

 

 

Don't church it up son it's a gaping hole you'll try to cover up. Why lockable? You afraid the cps will escape or something?

[Spinnakerblue89]

6 hours ago, ThatJeepGuy said:

 

Don't church it up son it's a gaping hole you'll try to cover up. Why lockable? You afraid the cps will escape or something?

You beat me to it.

[NC Tom]

1 hour ago, Spinnakerblue89 said:

You beat me to 

8 hours ago, ThatJeepGuy said:

 

Don't church it up son it's a gaping hole you'll try to cover up. Why lockable? You afraid the cps will escape or something?

 

No. But you never know when a very smart Mouse, Squirrel or Chipmunk finds it's way in. I live in the woods. Anything can happen. 😎

[89 MJ]

Before making a lockable lid, I’d just make a slightly larger panel and screw it over the hole. I’d worry that the lid would rattle. 

[NC Tom]

2 hours ago, 89 MJ said:

Before making a lockable lid, I’d just make a slightly larger panel and screw it over the hole. I’d worry that the lid would rattle. 

A rattle would suck! Actually, the truck is so loud, I wouldn't hear a rattle!

[JZLAJeep]

7 minutes ago, NC Tom said:

A rattle would suck! Actually, the truck is so loud, I wouldn't hear a rattle!

   

[TurboedMJ]

I'd use a lock... With how desirable a working CPS is these days, you never know...

[jeff351]

I looked at doing something like this on mine when I did my 97+ conversion. I think its certainly doable, like others pointed out, if you cut a hole, just make a cover that overlaps it about 1/2". Then drill some holes for sheet metal screws, apply some seam sealer, and button it up. Seam sealer would make it water proof and its not hard to break the seal once you remove the screws. 

[ThatJeepGuy]

32 minutes ago, jeff351 said:

I looked at doing something like this on mine when I did my 97+ conversion. I think its certainly doable, like others pointed out, if you cut a hole, just make a cover that overlaps it about 1/2". Then drill some holes for sheet metal screws, apply some seam sealer, and button it up. Seam sealer would make it water proof and its not hard to break the seal once you remove the screws. 

 

Imagine removing the seam sealed thin sheet of metal from the trans tunnel to "quickly" change the cps at a later date...

 

The level of disregard that would overcome you while swinging a small hammer at the poorly placed chisel in the space under the dash trim and next to the gas pedal

[jeff351]

57 minutes ago, ThatJeepGuy said:

 

Imagine removing the seam sealed thin sheet of metal from the trans tunnel to "quickly" change the cps at a later date...

 

The level of disregard that would overcome you while swinging a small hammer at the poorly placed chisel in the space under the dash trim and next to the gas pedal

I'll see if I still have the tube of sealer I used when I installed (and later removed) a trans tunnel cover. After applied, it was still flexible and wasn't overly hard to remove.