crank position sensor

[meathead40]

I have been reading these threads and think I have discovered my problem. (engine sputter). I check the crank position sensor and discovered that it had only had one loose bolt holding it in. the nub (looks like a pencil lead) apparently has been making contact with the fly wheel. only about a eighth of an inch of it remains. kind of chewed up on the end of it.
My question is this, would anybody happen to have a part number for it?
We have a Napa, Auto Zone, and a O'Rielly's in town. all their books only go back to 91 and nobody can seem to find a part number. (no dealer in town)
It is a 90 cherokee lerado. 4.0, aw-4 auto trans, np231

thanks

[RichP]

Dealer only item. And when you replace it don't drop any bolts in that hole othewise you will be dropping the tranny to get it out.

[martin]

Also for the Renix engine control (87-90) they offer two different CPS'. There is a "normal or standard" CPS and a "high altitude" CPS. They are identical other than where the sensor is mounted on the attachment plate. At my dealer both versions were the same price so more power for zero cost... that a no brainer!

The High alt CPS gives you some more advance which will translate into more power. You do not have to worry about knocking since our XJs have a knock sensor.

If you currently have a knock problem using 87 octane gasoline or have a knock problem after installing the high alt CPS then you need to change the knock sensor. The knock sensor is also a dealer only part.

[ACE]

Autozone and Checker Auto (Schucks, Kragen) both carry it. Autozone part # SU3228 and it's made by Wells. Checker part # is CSS87and it's a GP Sorensen brand. Here's what you will get from both Autozone and Checker Auto:
http://www.partsamerica.com/product_images/AAP/GPS/P0-PK/PC87.jpg

[Matthew Currie]

I don't know whether it is still the case, but formerly, if you bought the CPS upgrade kit for the 87-88 (same CPS as an 89 or 90), with an extra wire to bypass the notorious C-101 connector, it actually cost less than just the CPS! It's worth checking out at the dealer. The part should also come with a replacement for the plastic dust shield that snaps over the hole in the bell housing. If you use it, it will help hold the CPS in place when you install it, and also help you to avoid dropping screws into the void.

[Don Becker]

What, if any, are the downside(s) to using the high altitude cps (most of my driving is 100 to 2500 feet above sea level)? Will the engine run hotter, for example? Also, what is the "trick" for replacing it . . . . there's just no way I can get up in there . . . if I unbolt the transmission crossmember and lower the rear of the transmission/engine with a jack, will that allow access? In my 88, in it's 343000 miles, I 've had it replaced (at a shop) twice. But, I'd like to know the trick and to be able to do it myself.

[martin]

Don, There are no downsides to the high alt CPS provided your knock sensor is working. The knock sensor prevents engine knock and the computer will retard the timing until knock does not occur.

If you currently hear knocking using 87 octane then you need to change out the sensor. It is a dealer only item and costs around $75. I'd even recommend you replace it because of the high mileage on your XJ. I found my engine ran just a little better when I changed it and every other sensor for the engine.

The knock sensor has been redesigned and looks like a doughnut instead of an oxygen sensor. Mopar gives instrustions on how to install the new style sensor. You will need some red lock-tite to hold the nut on the stud, but that also covered in the instructions.

I do not consider my arm thin but I laid on my driveway and reached up to my CPS. I then found the right socket and removed both bolts making sure not to drop them into the bell housing.

I did not even consider unbolting my crossmember to do the job.

When you install the new CPS make sure you place the wire back in the holders on the engine to prevent it from being burned by the exhaust manifold.

[Vug]

1/4 drive socket and every extension you can beg, borrow, and steal from the neighbors

[Hawaiian Style]

Knock sensor is not a dealer only part. I bought one at Napa just a few months ago.

[Don Becker]

Thanks for the help!

Martin, I don't recall ever replacing the knock sensor (or, having had it replaced) either on this engine ('93 HO) or on the original (which went 325000 miles) and the engine runs like a clock right now. So, I'm a little disinclined to replace it unless, as you suggest, I detect some knocking w/the new cps. My only interest in the high altitude cps is for more power. I suspect much of the difference I see between the 88 and the 91 is in the differential gearing . . . but, gee, the 88 sure seems underpowered in comparison to the 91. Do you happen to know by how many degrees the high altitude cps advances the timing? Thanks again! Don

[martin]

Don, The Renix engine control was used 87-90. I am not sue if you are still using the Renix engine control or did you switch to the Chrysler control used since 91.

The Renix control has a knock sensor, the Chrysler control does not have a knock sensor. I have read on here ALL 4.0 blocks have the knock sensor mount cast into it, even the late 90s blocks. So if you are using a 93 engine with the 88 engine control then you need to hook up the knock sensor. It is located about cylinder #2 on the driver's side of the block.

Not knowing which engine control you are using it hard to answer. If you are getting knocking in you 88 and it still uses the renix control then time to buy or reconnect the knock sensor.

Two things to increase power I found on my 88 XJ was replacing the distributor with a NEW one not a rebuilt. Also installing the high altitude CPS. As the distributor bushings wear your timing is retarded.

On my 1969 Camero with the 230 straight 6 engine. We changed the distributor at 80K and 150K miles. So 70-80K is all I expect to get out of a distributor with that experience.

The 88 and 91 should have the same gearing if they both have the automatic transmission, this it also it true on the manual but 100%. I do know the manual ratio is like 3.07 while the auto like 3.54/3.55.

[dan f.]

pep boys also has both of these sensors. be patient with the cps install. i found the best way is to get a little kid to do it (small hands and arms). a buddy and i spent all day trying it, only to have my 12 year old brother succeed in a matter of minutes!
good luck

[Don Becker]

Thanks again! That's all great information and I appreciate it. Since my last post, I have discussed this with my mechanic and he is also doing some research. So, with what you fellows have provided, we should be able to make a decision and give this thing a little more "poop." Thanks! Don

[Matthew Currie]

Originally posted by Vug
1/4 drive socket and every extension you can beg, borrow, and steal from the neighbors

Steal a universal joint while you're at it. It works pretty well if you use socket, then about a 4-6 inch extension, then a universal, then a long extension, then a ratchet. Also make sure you have plenty of light from above.

[sidriptide]

i found that the easiest way to replace it is to use enough extentions to put the ratchet back near the trans crossmamber and sliding a lil farther up under the truck so the work area is just below my chest.. makes it a lil easier instead of wishing i could grow a 2nd elbow to get up in there.. i just use the "blind feel" method with the eys closed and the fingertips "seeing" the work.. i also tried talking my 7 yr old daughter into doing it but she didnt seem interested....
mike

[XJTripp]

I did mine and the only thing that worked for me was Sidriptide's method. I think I used two- 18", 3/8" extensions. You can feel it when your socket is on the bolt. I could slide a hand in there to guide the socket on, but I never could develop any torque without the long extensions to place the ratchet back near the trans body where things open up a little. Doing it that way I didn't use my universal.

[5-90]

I found a 42"x3/8" drive extension that works wonders for this job. Two other things - 1) get the "universal" 7/16" (or 11mm, they are effectively the same) socket - the one with the built-in u-joint. 2) Before you put in the new sensor (and modify all sensors you have to get later the same way!) you will want to take a Dremel and open the "bottom" slot (as mounted) out toward the end of the bracket, and the "top" slot (again, as mounted) straight out the side of the bracket toward the bottom. Sorry I haven't a picture, but if you are careful to not distort the mounting holes, you will not have to fight to keep the sensor in place while wrestling with the bolts. You will need to remove them to get out the old sensor, but you can put them back in loosely and slip the new sensor over them with minimal difficulty, and slip it in and out next time you need to get in there!

Yes, the L-O-N-G extension did help - I did the job last time in about 15 minutes, and I'm 6'3"/226#! I don't have any small children to borrow, either... The "universal" socket will give you just enough wiggle to drop right onto the bolts!

Remember that the early (1987-90) sensor is some sort of MAD pickup (voltage generating,) while the later version (1991-up) is a Hall Effect switch, and the two do NOT rpt NOT interchange. The later Hall Effect-type is what you are finding in the aftermarket parts world, as the early Renix sensor is strictly OEMR only. Leastways, I haven't found it anywhere else just yet...

5-90

[Don Becker]

I'M A BELIEVER!!! I just picked-up my '88 from my mechanic. I had him install the high altitude CPS. Oh, this thing runs soooooo sweet! I've only driven it, maybe 4 miles, back to the office. It has the get-up-n-go that my wife's '91 has (the 91 is a factory rebuilt 4.0L HO and the '88 has a 4.0L HO (low mileage) from a '93 XJ) and it just seems to run smoother, too . . . . . Thanks again, Guys!!!!!!! Don