What CPS for my '97 Wrangler and do I need a new one?

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Alemonkey

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Hi everyone, just bought my first Jeep ever the other day. It's a 97 Sport with the 4.0 and a manual transmission. It's in really good shape overall, the only rust is on the front fenders which someone covered up with some cheesy diamond plate fender protectors. This is going to be a vehicle for my daughter for the next couple years, so I am planning on not sinking too much money into it until she's done with high school. Once she finishes up then Dad gets a toy and I'll replace the fenders... Assuming she doesn't wreck it. She loves Jeeps, so this should be a fun father/daughter project.

So, now the bad. A previous owner removed the catalytic converter and left the downstream O2 sensor hanging, which eventually broke in half. I'm actually glad they didn't just unplug it, because at least the connector was still in good shape and not corroded when I unplugged what was left of the sensor. Of course with this kind of hack job the CEL is on, and I have P0141, P0138, and P0320 codes.

I'm reasonably certain the P0141 and P0138 are both due to the missing cat and sensor, but is there any possibility that those could be the cause of the P0320? I've read that the CPS can cause that code, and since it's an older vehicle maybe I should just replace it anyway while I'm at it. If so I'll go with a genuine Mopar part, but I'm a little confused what part number I need. Do all the 4.0 TJ's need the same sensor? Different parts houses online have given me different part numbers.

I have a complete new exhaust from the manifold back on order, along with new NGK O2 sensors, so hopefully soon I'll have this thing back to running like it should.
 
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I can't say for sure, but the right thing to do is replace the O2 sensor (it's a wise idea to replace both of them at once) and see what happens after you do that and clear the codes (you'll need to either clear the codes with a code reader or unplug the battery for 10 minutes or so after replacing the sensors).

Make sure you ONLY use NGK replacement sensors, otherwise the codes will not go away (this is a known issue with TJs).

You can find the correct sensors and read more about the NGK sensor thing here:

The Official Jeep Wrangler TJ Oxygen (O2) Sensor Thread

I'd love to tell you to go out and replace the CPS (by the way, if you do, ONLY use a Mopar sensor, otherwise you'll have issues), but starting with the O2 sensors first is the way I would do it.
 
That will be the least of your problems once all the boys around there zero in on a girl with a Jeep.

Load your gun.
 
The cps sensor is unique to the 1997 4.0l

What ever CPS sensor specta uses has worked in my TJ. I did a complete distributor change. Is was relatively inexpensive and easy to do. For

This is the distributor that I personally used and have had no issues with. For $45 you get a new cap, rotor, cam sensor, and distributor.

Spectra Premium CH15 Distributor https://www.amazon.com/dp/B001DAHM0C/?tag=wranglerorg-20

I have almost 1 year on it. No codes from the cps.


If it is the crank position sensor. I have not had to replace mine.
 
Thanks, the O2 sensors I ordered are NGK. I've done enough lurking here to know that trying anything else is a lost cause. I ordered both because I figured I might as well replace them while I was doing a whole new exhaust, even though only the (missing) downstream one is throwing a code.

I'll probably wait on the CPS for now and see if the code returns after I finish up the exhaust & O2 sensors. Is 68407888AA the correct part number for the 1997?

Boinked, thanks for the link to the distributor. I was thinking of maybe replacing that eventually, too, along with new plugs and wires, just because it's an old vehicle and I have no idea when any of that was last done.
 
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Alemonkey said:
Thanks, the O2 sensors I ordered are NGK. I've done enough lurking here to know that trying anything else is a lost cause. I ordered both because I figured I might as well replace them while I was doing a whole new exhaust, even though only the (missing) downstream one is throwing a code.

I'll probably wait on the CPS for now and see if the code returns after I finish up the exhaust & O2 sensors. Is 68407888AA the correct part number for the 1997?

Boinked, thanks for the link to the distributor. I was thinking of maybe replacing that eventually, too, along with new plugs and wires, just because it's an old vehicle and I have no idea when any of that was last done.
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That does look like the correct sensor. I also agree with you that you should wait until the exhaust system is done first.

Clear the codes and see if it pops back up.

There are several videos on testing the crank position sensor on YouTube. It could save you $100 if it is something other than the sensor
 
Ok, one more question. Do you guys think I should even bother trying to undo the bolts that hold the front exhaust pipe to the manifold, or should I just cut the pipe a little further back and splice it together? I've been squirting penetrating oil on them once or twice a day for about a week in anticipation of trying to remove them, but they're looking pretty corroded.
 
This is my opinion. . .

I would first try to unbolt them normally.

If that fails if you have a dremel you can cut the bolts pretty easily. The bolts are not permanently attached to the manifold like the old style studs. Then you can replace the bolts.

I would only splice it as a last resort.
 
Well, this past weekend I got the new exhaust installed along with all new O2 sensors, then I cleared the codes. Only about 20 miles on it since then, but no new codes have occurred since then. So hopefully that means the O2 sensors by themselves did the trick. It's definitely running a lot better. Now instead of a roaring exhaust I get to hear that nice 4.0 rattle :LOL:. Thanks for the help, everyone.
 
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