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sync sensor

87manche said:
unplugging the sync sensor should have made it worse than before.
if there wasn't any change then it seems to me that the sync sensor wasn't doing it's job in the first place.
Click to expand...

Concur. It would be the first one I've heard of failing, but it's a possibility.

If you disconnect a sensor, and it doesn't change anything, the sensor was shot to begin with - you'll end up replacing.

To replace the SYNC sensor, you need to pull the distributor. There's a roll pin that holds the gear on - drive it out, pull the gear off the bottom, and pull the shaft out the top. There are, I believe, two screws that hold the SYNC sensor down - remove those, change the sensor, and replace.

NOTE - make a "match mark" on the dizzy gear and shaft. Also:

When you remove the cap, make two marks where the rotor is pointing. Pull the dizzy, DO NOT move the rotor, and make a SINGLE mark where the rotor points after you get the thing out.

When you put it back in, make sure the gear is lined up with the match-mark on the shaft, align the rotor with the SINGLE mark you made, and install. Make sure the rotor lines up with the DOUBLE mark you made after it's fully seated... (Can you tell I've pulled a few distributors before?)

I find a Sharpie pen good for the rotor marks, and use a scribe for the gear marks. Reason for the Sharpie up top? If I ever have to pull the dizzy again, it's a cinch that the rotor won't be in the same place, and I can't be arsed with turning the engine - easier to sand the marks off and make new ones...

5-90
 
they also make different colored sharpies now, I've found that the metallic ones are brilliant for marking on these sorts of things, much easier to see in low light conditions often found under the hood.
 
will try that. i will start with the cps it seems easier. and taking the dizzy off sounds. complicated but i will get around to it. can you buy the sensor at autozone or is it a dealer thing?
 
is there some kind of sealer around the cps sensor. when i put a new starter in today i when up and felt around where it is and it felt like there was stuff moving in there. the jeep was sitting for 2yrs and im wondering if something made a nest. i might pull it off and see what happens. and i just noticed when i did my cam sensor test. i had a vacuum line disconnected. this may be why i didn't see any difference.
 
A vacuum leak will cause either a "wandering" or "hunting" idle, or a high idle. The engine should still start just fine.

As far as the CPS goes, some have reported a rubber plug around the sensor body, closing the bellhousing hole. I finally saw one on the AX-15 I pulled to repalce my Peugeot (and I've seen a bunch of XJ gearboxes by now!) so it probably falls out or doesn't get replaced.

5-90
 
im wondering if its sort of stuck under the sensor not making a full strength signal. seeing that no one has replaced the cam sensor. i will work with the cps knowing that it has the potential to go bad. i will try to just "clean it" and see what i can do.
 
A tape head degausser should work, but I don't know if they can be had anymore. I'm not sure how to build one - I've probably got instructions somewhere, but if I do, I haven't seen them in 10 years or so.

Have you tried Google? "Degausser" or "demagnetizer" should yield results...

5-90
 
Nope - a "bulk eraser" is a different animal. It's meant to take the semi-ordered magnetic patterns on recorded media and effectively realign them in a single direction, erasing the information.

A "degausser" is used to take a device with is not supposed to have a magnetic field, but picked one up anyhow, and randomise the orientation of the "magnetic" particles (usually iron salts,) in an effort to destroy the magnetic field.

5-90
 
well im just going to pop it out and check the hole. i have one at my school somewhere but its a matter of finding it. and i hope it is big enough. i think its for screwdrivers.
 
90xj06 said:
well im just going to pop it out and check the hole. i have one at my school somewhere but its a matter of finding it. and i hope it is big enough. i think its for screwdrivers.
Click to expand...

Should be plenty. Degaussers for magnetic media heads are necessarily not very large - you don't want to depolarise the drive motor, if it's a permanent magnet motor. That would suck.
 
I hate to be the one to ask this question, but when you say it takes a long time to start. How long? renix motors take a little longer than others to start, They won't fire till the cps shows 300 rpm. They will, however, fire without the sync sensor. The compuer just selects a random sequence and goes on with it. if this is happening it will add a few seconds to your start time.

I bring this up because while I definitely encourage you to spend quality time going over all your underhood electrical connections, i think you may be trying to fix something that isn't broke.

You should also keep in mind that this long crank time is also partially responsible for the renix xj's longevity. the extra time to get oil pressure up before dealing with actual combustion definitely helps these motors lat longer. I have three renix xj's tw 4.0's and a 2.46ish four cylinder. all of them have over 200,000 miles on them. and all of them still run nicely. two of them have REALLY rough bodies, but they all run nicely.
 
5-90 said:
A vacuum leak will cause either a "wandering" or "hunting" idle, or a high idle. The engine should still start just fine.

As far as the CPS goes, some have reported a rubber plug around the sensor body, closing the bellhousing hole. I finally saw one on the AX-15 I pulled to repalce my Peugeot (and I've seen a bunch of XJ gearboxes by now!) so it probably falls out or doesn't get replaced.

5-90
Click to expand...

The sensors I've bought have always come with a stiff plastic shield that snaps in. As far as I recall that includes both the two Renix ones I've done and one for the 93. I found it very handy, because the shield holds the sensor in place somewhat, allowing one to place it from above, then crawl underneath to put in the bolts.
 
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